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iTRAQ-based mitochondrial proteome analysis of the molecular mechanisms underlying postharvest senescence in Zizania latifolia

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Journal of Food Biochemistry
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To explore the molecular mechanisms underlying postharvest senescence of Zizania latifolia, the changes in the mitochondrial proteome of plants treated with or without (control) 1‐methyleyelopropene and ethylene during storage at room temperature for 0, 3 and 6 days were investigated using isobaric tags for relative and absolute quantitation (iTRAQ) labeling combined with two‐dimensional liquid chromatography‐tandem mass spectrometry. A total of 1,390 proteins with two or more peptides were identified, of which 211 showed a significant (p < .05) change (at least twofold) in relative abundance. Monitoring the parallel reaction validated the reliability and accuracy of the iTRAQ results. Bioinformatics and functional analysis of these differentially expressed proteins (DEPs) revealed that postharvest senescence of Z. latifolia could be attributed to (a) strengthened pentose phosphate pathway, (b) imbalanced protein, amino acid, organic acid, and fatty acid metabolism, (c) disordered energy homeostasis, (d) exacerbated oxidative damage, (e) RNA degradation, (f) activation of the Ca²⁺, mitogen‐activated protein kinase, and jasmonic acid signaling pathways, (g) programed cell death, (h) excessive biosynthesis of secondary metabolites, or (i) degradation of cell structure. Our findings provide integrated insight into the molecular mechanisms of postharvest senescence during storage as well as the DEPs that show promise as targets for controlling senescence‐induced quality deterioration of Z. latifolia. Practical applications Postharvest senescence is the most important factor that causes fast quality deterioration of Zizania latifolia. The understanding of the processes leading to postharvest senescence of Z. latifolia is essential in enhancing the commercial value and extending the shelf life of the product. It is currently believed that the mitochondrial metabolism is closely related to postharvest senescence. For this, the changes of proteome in Z. latifolia mitochondria treated with or without (control) 1‐MCP and ETH during storage at room temperature were investigated. Results showed that a variety of physiobiochemical responses occur during postharvest senescence of Z. latifolia. 1‐MCP treatment significantly inhibited the changes of these physiobiochemical processes, finally, retarding the postharvest senescence of Z. latifolia. ETH treatment had opposite effects on proteome changes compared with 1‐MCP treatment. Taken together, these results enrich the understanding of the molecular mechanisms of postharvest senescence of Z. latifolia.
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J Food Biochem. 2019;00:e13053. wileyonlinelibrary.com/journal/jfbc  
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 1 of 20
https://doi.org/10.1111/jc.13053
© 2019 Wiley Periodicals, Inc.
Received:19June2019 
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  Revised:1A ugust2019 
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  Accepted:20Augus t2019
DOI : 10.1111/jfbc .13053
FULL ARTICLE
iTRAQ‐based mitochondrial proteome analysis of the
molecular mechanisms underlying postharvest senescence of
Zizania latifolia
Haibo Luo1| Tao Zhou1| Xiaoxue Kong1| Mingxuan Tao1| Jiaxin Zhang1|
Weihua Wang2| Li Jiang2| Lijuan Yu3| Zhifang Yu2
1School of Food Science and Pharmaceutical
Engineering, Nanjing Normal University,
Nanjing, P.R. China
2College of Food Scie nce and Techn ology,
NanjingA griculturalUniversity,Nanjing,
P.R. China
3InstituteofAgro‐ProductsProcessing,
YunnanAcademyofAgriculturalSciences,
Kunming, P.R. China
Correspondence
Li Jiang, College of Food Science and
Technology,NanjingAgriculturalUniversity,
Nanjing , Jiangsu, 210095, P.R. China.
Email: jiangli@njau.edu.cn
LijuanYu,InstituteofAgro‐Products
Processing,YunnanAcademyofAgricultural
Science s, 650221, Kunming , P.R. China .
Email: yulijuan1000@163.com
Abstract
To explore the molecular mechanisms underlying postharvest senescence of Zizania
latifolia, the changes in the mitochondrial proteome of plants treated with or without
(control) 1‐methyleyelopropene and ethylene during storageat room temperature
for 0, 3 and 6 days were investigated using isobaric tags for relative and absolute
quantitation(iTRAQ)labeling combinedwith two‐dimensional liquidchromatogra
phy‐tandemmassspectrometry.Atotalof1,390proteinswithtwoormorepeptides
were identified, of which 211 showed a significant (p < .05) change (at least twofold)
in relative abundance. Monitoring the parallel reaction validated the reliability and
accuracyoftheiTRAQresults.Bioinformaticsandfunctionalanalysisofthesediffer
entially expressed proteins (DEPs) revealed that postharvest senescence of Z. latifolia
could be attributed to (a) strengthened pentose phosphate pathway, (b) imbalanced
protein, amino acid, organic acid, and fatty acid metabolism, (c) disordered energy
homeostasis,(d)exacerbatedoxidativedamage,(e)RNAdegradation,(f)activation
of the Ca2+,mitogen‐activatedproteinkinase,andjasmonicacidsignalingpathways,
(g) programed cell death, (h) excessive biosynthesis of secondary metabolites, or (i)
degradation of cell structure. Our findings provide integrated insight into the molecu
lar mechanisms of posthar vest senescence during storage as well as the DEPs that
showpromiseastargetsforcontrollingsenescence‐inducedqualitydeteriorationof
Z. latifolia.
Practical applications
Postharvest senescence is the most important factor that causes fast quality deterio
ration of Zizania latifolia. The understanding of the processes leading to posthar vest
senescence of Z. latifolia is essential in enhancing the commercial value and extending
the shelf life of the product. It is currently believed that the mitochondrial metabo
lism is closely related to postharvest senescence. For this, the changes of proteome
in Z. latifoliamitochondriatreatedwith orwithout(control)1‐MCPandETHduring
storage at room temperature were investigated. Results showed that a variety of
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1 | INTRODUCTION
Zizania latifolia (Griseb.) Turcz. ex Stapf., which is widely distributed
throughoutSoutheast Asia, is a perennial aquatic grassthat grows
alongthelittorals offreshwaterlakes,streams,marshes,and pools
(Fan, Ren, Liu, & Chen, 2016; Li et al., 2019). The plant is usually
parasitized by the smut fungus Ustilago esculenta P. Henn., wh ich
causes thickening and enlargement of the culms. Swollen culms
are commonly called “Jiaobai” in China, “Gausun” in Taiwan, and
“Makomotake”inJapan(Joseetal.,2016)andarewidelyconsumed
asahealthy vegetable in several Southeast Asian countries, espe‐
cially in China, Japan, Taiwan, Vietnam, and India, in which they
haveaconsiderableeconomicimpact(Choietal.,2015;Sinha,Deka,
& Bharal ee, 2016; Yan et al., 2013). However, posth arvest sen es‐
cence of Z. latifolia rapidly undergoes senescence and deterioration
at ambient temperatures. It s vegetable quality is reduced due to
shell etiolation, surface browning, flesh lignification, and tissue hol
lowness. Consequently, the shelf life of postharvest senescence of
Z. latifolia is typically only 2–3 days at room temperature (Wang
et al., 2017). Th us, unraveling the molecula r and biochemical changes
that occur during posthar vest senescence of Z. latifolia has biological
and economic importance and enables the development of strate
gies to preserve postharvest quality.
Plant senescence is af fected by respiratory metabolism,
which provides the energy for diverse biochemical processes (Li,
Limwachiranon, Li, Du, & Luo, 2016; Yang, Cao, Su, & Jiang, 2014).
The imbalance in energy metabolism caused by changes in respira
tory metabolism is an early manifestation and basic characteristic
of plant senescence (Jiang et al., 2007; Li et al., 2018). Increasing
evidence suggest s that appropriate energ y production in harvested
horticultural crops is essential for the maintenance of cell func
tions, but energy level requirements may var y between climacteric
and nonclimacteric vegetables (Jiang et al., 2007). Oxidative dam
age to proteins, lipids, and nucleic acids caused by intracellular re
active oxygen species (ROS),a resultof electron leakage from the
respiratory electron transport chain (ETC), has been implicated in
plantsenescence(Qin,Meng,Wang,&Tian,2009;Wuetal.,2016).
Mitochondria are responsible for adenosine triphosphate (ATP)
synthesis, calcium signaling, ROS production, cell cycle arrest via
programedcelldeath, amongotherfunctions (Liu et al., 2016;Qin,
Wang, Liu, Li, & Tian, 2009). Functional integrity is a critical require
ment for mitochondria to meet the cellular energy demand. Thus,
accurate assessment of mitochondrial protein components and the
changes in their abundance would provide insight into the molecu
lar mechanisms underlying the postharvest senescence of Z. latifolia
during storage.
Proteomic s enables the evaluation of global changes in the com
position and abundance of proteins associated with plant senes
cence and the effec ts of posthar vest treatment s on the vegetable
proteome (Das, Chua, Lin, & Wong, 2019; Liet al., 2015). Two‐di‐
mensionalelectrophore sis(2‐DE)isfrequentlyusedtoseparatepro
teins prior to their identific ation by mass spectrometry (MS). Indeed,
analyses of the mitochondrial proteomes of the peaches (Wu et al.,
2016),apples(Qin, Wang, et al.,2009),rice(Chen et al.,2009)and
Arabidopsis (Millar, Sweetlove, Giegé, & Leaver, 2001) have been car
riedout.However,noinformationisavailableonchangesinthepro‐
tein profiles of Z. latifolia mitochondria in response to senescence. In
addition, it is difficult to separate extremely large/small, acidic/basic,
andhighlyhydrophobicproteinsbytraditional2‐DE.
Theisobarictagsforrelativeandabsolutequantitation(iTRAQ)
techniqu e, which was develo ped by Applied Bio systems in 200 4,
enables high proteome coverage and multiplex labeling (Long
etal.,2019).iTRAQhasbeenappliedtoavarietyofplants,includ
ingpeaches(Huan et al.,2019),apples(Zhengetal.,2018),maizes
(Yu et al., 2017), soybean sprouts (Jiao & Gu, 2019), potatoes (Liu
et al., 2015), cucumber plants (Fan, Xu, Du, & Wu, 2015), tomato
roots(Gongetal.,2014),strawberries(Li,Li,Luo,Huang,&Li,2016),
and Citrus sinensis roots ( Yang et al., 2 013).H owever,t o the best
ofourknowledge,themitochondrialproteomeofZ. latifolia has not
beenanalyzedbyiTRAQtechnique.
Ethylene (ETH) is an endogenous plant hormone that plays an
important physiological role in postharvest ripening and postharvest
senescence of horticultural crops (Xu et al., 2018). Modulating the
biosynthesis of ETHisanimportant approach to prolong the shelf
lifeofharvestedhorticulturalcrops.1‐methylcyclopropene(1‐MCP),
aninhibitorofETH,bindsstronglyandirreversiblytoETHreceptors,
preventingtheETHeffectsonplanttissuesanddelayingsenescence
(Luo,Xu,&Yan,2008;Minetal.,2018).1‐MCPhascommercialpo
tentialfor controllingETH‐dependentprocessessuchas ripening,
senescence, yellowing, and softening and for extending the shelf
physiobiochemical responses occur during postharvest senescence of Z. latifolia. 1‐
MCP treatment significantly inhibited the changes of these physiobiochemical pro
cesses, finally, retarding the postharvest senescence of Z. latifolia.ETHtreatmenthad
oppositeeffects onproteomechangescomparedwith1‐MCPtreatment.Takento‐
gether, these results enrich the understanding of the molecular mechanisms of post
harvest senescence of Z. latifolia.
KEYWORDS
iTRAQ,mitochondria,respiratorymetabolism,senescence,Zizania latifolia
    
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life of vegetables such as broccoli (Xu et al., 2016), green bell pep
pers(Cao,Zheng,&Yang,2012), tomatoes(Steelheartetal.,2019),
and “iceberg” lettuces (Saltveit, 200 4). Song et al. (2010) found that
1‐MCPdelayedsenescencebyinhibitingETHproduction,decreasing
cellulose and protopectin contents, and maintaining cell inclusions of
peeled Z. latifolia.We previously reported that1‐MCP significantly
retarded the postharvest senescence of Z. latifolia during storage at
room temp erature (Wan g et al., 2017). However, the mec hanisms
underlyingtheeffectsof1‐MCPandETHonvegetablesenescence
and quality deterioration are unclear.
The objec tives of this study were to (a) evaluate the effects of
1‐MCP and ETH on posthar vest senescence of Z. latifolia during
storage at room temperature (25°C), (b) assess the effects of post
harvest1‐MCPandETHtreatmentsonthemitochondrialproteome
of Z. latifoliausingtheiTRAQtechnique,and(c)identifythesenes
cence‐responsiveproteinsin Z. latifolia mitochondria and the mo
lecular mechanism underlying postharvest senescence of Z. latifolia
during storage at 25°C .
2 | MATERIALS AND METHODS
2.1 | Plant material
Fresh Z. latifoliastemswerehand‐harvestedinJuly9,2016from a
commercialfarmlandin Dabieshan, Anhui, Chinaand immediately
transported to the KeyLaboratoryofFoodProcessingandQuality
Controlof MinistryofAgriculture,NanjingAgricultural University.
They were selected for uniform size, color, and absence of visible de
fects and Z. latifoliawasrandomlydividedintothreegroupsof15kg
each. The first group of Z. latifoliawastreatedwith10µl/L 1‐MCP
(AgroFresh,Philadelphia,USA)inasealedchamberatroomtemper‐
ature (25°C) for 20 hr; the second group was immersed in 1,00 0 µl/L
ETH(SinopharmChemicalReagentBeijingCo.,Ltd,China)solution,
air‐dried,andplacedinasealedchamberat25°Cfor20hr;andthe
third group was subjected to the same conditions without exposure
to 1‐MCP or immersion in ETH solution (control, CK). Following
the treatment, the chambers were opened and all Z. latifolia were
stored at 25°C for five days. Z. latifolia samples were removed at Day
0(beforetreatment,CK0),Day3(CK3,1‐MCP3,ETH3),andDay6
(CK6,1‐MCP6,ETH6),respectivelyandmanuallypeeledcarefullyto
removeroots.Next, a5‐cm‐longportionof the stemwasremoved
from each end of Z. latifoliausingasharpstainlesssteelknife;there
mainder was used for indices analysis or immediately frozen in liquid
nitrogenandstoredat−80°Cuntilrequired.
2.2 | Determination of color, respiration rate, and
weight loss
The color of the Z. latifolia surface was determined using the Chroma
MeterCR‐400(KonicaMinolta,Inc.,Japan)intheCIEL* a* b* color
space. Ten Z. latifolia per replicate were used.
Ten Z. latifolia with three replicates each at Day 0, Day 3, and
Day 6 were enclosed in 8.7 L glass jars at 20°C for 1 hr. The CO2
concentration was measured using a headspace gas analyzer
(CheckMate3, PBI Dansensor,Denmark)and is expressedin milli‐
grams CO2perkilogramfreshweightperhour.
Weight loss was examined in 10 Z. latifolia per treatment and is
expressed as a percentage of the initial weight.
2.3 | Visualization of ultrastructure
Cell ultr astructure was visualized accordin g to Li, Zhang, and Ge
(2017) and Wu et al. (2017) with some modifications. Z. latifolia
pieces (5 × 5 × 1 mm) from the cut surface of three Z. latifolia per
treatment were excised using a blade and fixed in 2.5% (v/v) glutaral
dehydefor4hrfollowedbythreewasheswithcoldphosphate‐buff‐
eredsaline (PBS,0.1mol/L,pH7.2)for15mineach.Subsequently,
thesamplesweresoakedin2%(w/v)osmicacidfixativesolutionfor
2hr andwashedthricewithPBS.The sampleswere dehydratedin
30%, 50%, 70%, 80%, and 90% ethanol for 15 min each, followed
by 100% acetone for 20 min. Next, they were permeated and em
bedded inepoxyresinandcut intoslices of50nmthickness.After
staining with uranium acet ate and lead citrate, the cell structure
was observedusing the H‐7650transmissionelectron microscope
(Shanghai Ranchao Photoelectric Technology Co., Ltd, China).
2.4 | Mitochondrial isolation
Mitochon dria were isolate d according to Qin and c oworkers with
somemodifications(Qin,Meng,etal.,2009;Qin,Wang,etal.,2009).
Allstepswereperformedat4°C.Planttissues(150g)werehomog‐
enized using a blender in 450 ml of cold ex trac tion buffer containing
50 mM Tris‐HCl (pH 7.5), 250 mM suc rose, 1 mM ethyle nediami‐
netetraaceticacid(EDTA),0.1%(w/v)bovineserumalbumin(BSA),
0.5%(w/v)polyvinylpyrrolidone‐40,and10mMβ‐mercaptoethanol.
The homogenate was filtered through four layers of sterile cheese
cloth and centrifuged at 3,000× g for 15 min. The supernatant was
decanted and centrifuged at 16,00g for 15 min. The pellet was
resuspended in 30mlofcold washbuffercomprising10mMTris‐
HCl(pH7.2),250mMsucrose,300mMmannitol,1mMEDTA,and
0.1% (w/v) BSA. The cru de fractio ns were separate d on a Percoll
step discontinuous density gradient at 20%, 24%, and 45% (2:4:2)
inwashbuffer.Aftercentrifugationat40,000×g for 45 min, the mi
tochondria had accumulated at the interface between the 24% and
45% Percoll layers. The mitochondria were aspirated and washed by
centrifugation at 15,00g for 15 min in wash buffer and the pellet
was collected.
2.5 | Protein extraction
Protein extraction was performed as described by Isaacson et
al. (2006) with some modifications. The mitochondrial pellet was
crushed to a fine powder in liquid nitrogen, precipitated with 10 ml
ofcoldacetone containing10%(w/v)trichloroacetic acid at −20°C
for 1 hr and centrifuged at 15,000× g for 15 min at 4°C. The de
posit was washed twice with cold acetone as in the previous step
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and lyophilized in a vacuum freeze dryer ( Thermo Savant, Germany)
for 5 min. The powder was collected, immediately mixed with 3 ml
ofcoldTris‐HCl‐saturatedphenol(pH7.5),andshakenfor30minat
4°C.Aftercentrifugationat5,000×g for 30 min at 4°C , the phenolic
phase was collected and precipitated with five volumes of cold 0.1 M
ammoniumacetateinmethanolat−20°Cfor1hr.Precipitatedpro‐
teins were centrifuged at 10,00 g for 10 min at 4°C and washed
twice with five volumes of cold methanol, followed by t wo washes
with cold acetone. The deposit was vacuum dried and dissolved in
lysis buffer at 30°C for 1 hr. The supernatant was centrifuged at
15,000× g for 15 min at 4°C and the protein concentration was de
termined by the bicinchoninic acid method (Smith et al., 1985) using
BSAasthestandard.
2.6 | Trypsin digestion and iTRAQ labeling
Trypsin digestion was performed as described by Wisniewski,
Zougman, Nagaraj, and Mann (2009). Protein samples (100 μg
each) were reduced with 10 mM dithiothreitol for 1 hr at 60°C and
alkylatedwith55mMiodoacetamidefor10minatroomtempera
ture in dar kness. Afte r digestion wit h sequencing g rade tryp sin
gold(Promega,Madison,USA)atatrypsin:proteinratioof1:40at
37°C for 12 hr, the samples were reconstituted in 0.5 M triethyl
ammonium bicarbonate buffer (Sigma) and labeled with iTRAQ
reagentsusinganeight‐plexiTRAQkit(ABSCIEXInc.,Foster,MA,
USA)accordingtothemanufacturer'sinstructions.Theproteindi
gests obtained from the CK0, CK3, ETH3, 1‐MCP3, CK6, ETH6,
and1‐MCP6treatmentswerelabeledwithiTRAQreagents113,
114, 115, 116, 117, 118, 119, and 120, respectively and incubated
at room temperature for 2 hr. Identical quantities of peptide mix
tures from the above seven samples were labeled with reagent
121 and served as the sample internal standard (IS). The peptide
mixtureswerepooledandvacuumdriedfortwo‐dimensionalliq
uidchromatography‐tandemMS (2D‐LC‐MS/MS)analysis.Three
biological replicates of each sample were labeled with iTRAQ
reagents.
2.7 | 2D‐LC‐MS/MS
2. 7.1 | Fractionation by strong cation exchange
chromatography
Dried peptide samples were reconstituted in 100 µl of strong cat
ionexchangebufferA(10mMKH2PO4in25%acetonitrile,pH2.7)
and frac tionated by strong cation exchange chromatography on
the Agilent 1200 HPLC system (Agilent Technologies, Inc., USA)
equipped with a Poly‐SEA 2.0 × 150 mm column (5 µm, 300 Å ,
Michrom). The peptides were eluted at a flow rate of 0.3 ml/min in
anonlinearbinarygradientstartingwithbufferAandtransitioning
tobufferB(10mMKH2PO4, 500mM KCl in 25% acetonitrile, pH
2.7):0%–5%bufferBfor5min,5%–50%Bover35min,50%–80%
Bover5min(maintainedfor5min),andreturnto5%Bover10min.
The elution was monitored by measuring the absorbance at 215 nm
and 280 nm. In total, 12 fractions were collected, vacuum dried, and
storedat−80°CuntilLC‐MS/MSanalysis.
2. 7. 2| Reversed‐phase liquid chromatography
(RPLC)‐tandem MS/MS analysis
Sample s were reconstitu ted in Nano‐RPLC buf fer A (0.1% formic
acidand2%acetonitrile).OnlineNano‐RPLCwasperformedonthe
EksigentnanoLC‐Ultra™2DSystem(ABSCIEX).Thesampleswere
loadedontoaC18nanoLCtrapcolumn(100µm×3cm,3µm,150Å)
and washe d with Nano‐RPLC bu ffer A at a flow rate of 2 μl/min
for 10 min. Af ter desalting , peptides were s eparated usin g a C18
reverse d‐phase column (75 μm × 15 cm, 3 μm , 120 Å, ChromXP
Eksigent).Thegradientwasrunat250nl/minfrom5%to30%buffer
B(80%acetonitrileand0.1%formicacid)over70min.
Triple time‐of‐flight (TOF) analysis was performed using the
Triple TOF 5600 System (AB SCIEX) fitted with a Nanospray III
source (AB SCIEX) and a pulled quartz tip as the emitter (New
Objectives,Woburn,MA,USA)accordingtoZhuetal.(2014).Data
wereacquiredusinganionsprayvoltageof2.5kV,curtaingasof30
PSI, nebulizer gas of 5 PSI, and an interface heater temperature of
150°C . For informatio n‐depende nt acquisition , survey sca ns were
acquired over 250 ms and up to 35 produc t ion scans were collected
if they exceeded a threshold of 150 counts/s with a 2+ to 5+ charge
state. The totalcycletime was fixedat2.5s.Arollingcollisionen‐
ergy settingwas applied to allprecursor ionsfor collision‐induced
dissociation. Dynamicexclusion was set for 1/2 peak width (18s)
and theprecursor was refreshed off the exclusion list (Hou et al.,
2015).
2.8 | Protein identification and quantification
The original MS/MS file data (*.wiff) were analyzed using Protein
Pilot Sof tware v. 5.0 (AB SCI EX) agains t the Oryza sativa UniProt
database using the Paragon algorithm (Shilov et al., 2007). The da
tabase search parameters were as follows: The iTRAQ eight‐plex
(peptide labeled) was chosen for protein quantification with at least
two unique peptides during the search and a global false discovery
rate from a fit of <1% was considered for fur ther analysis. Relative
quantitation was performed by ttestforthreereplicates.Atwofold
threshold was set to determine up and downregulated proteins using
a p value < .05.
2.9| Bioinformatics analysis
Bioinformatics analysis of the differentially expressed proteins
(DEPs) was performed using the tools available from DAVID
BioinformaticsResources6.8(http://www.geneontology.org/).The
DEPs were annotated by gene ontolog y (GO) analysis according
tothebiological process (BP) andmolecularfunction (MF)catego‐
ries (Sun et al., 2015). Kyoto Encyclopedia of Genes and Genomes
(KEGG) analysis was performed using the KEGG database (http://
www.genome.jp/kegg/pathway.html)(Chuetal.,2015).
    
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2.10| Validation of DEPs
Based on the results of the large‐scale quantitative proteomics
study, proteins were selected for validation by targeted MS analysis
using parallel reaction monitoring (PRM) on the Triple TOF 5600+
LC‐MS/MS system (S CIEX). The p rotein extr action and tr yptic di‐
gestion procedures were the same way as those per formed in the
iTR AQexperiment.MSdataacquisitionwasfirstper formedindata‐
dependent acquisition mode to obtain MS/MS spectra for the 40
most abundant precursor ions following each MS1 sur vey scan in
each cycle. ProteinPilot software was used to identify proteins and
thedatabasesearchresultswereimportedintotheSkylinesoftware
for the spectral librar y building. Target proteins for PRM validation
wereimportedintoSkylineandthepeptidesforproteinquantifica‐
tion were selected according to the ion signals in the spectral library.
Alistofassociatedpeptideswithm/z values and retention times was
exportedfromSkylineandthenimportedintotheMScontrolsoft‐
ware Analyst for PRM acquisitionmethod construction. The PRM
method was run against the biological samples of interest, evaluated,
and refined to develop the highest quality assay. Data collection
wasperformedusingthefinalPRMacquisitionmethodonaQqTOF
mass spec trometer, in which each precursor ion was selected by the
quadrupole and fragmented, and then all fragment ions were quanti
fied by the TOF mass analyzer. To eliminate the protein carryover, a
“blank”wasrunbetweenadjacentsamplesforcolumnwashing.Data
processingwasperformedinSkylineandthequantificationresults
were manually inspected for each peptide of the target protein.
2.11 | Statistical analysis
Statistical analysis was performed using SPSS 19.0 software (SPSS
Inc.,Chicago,IL,USA).Dataareexpressedasmeans±standardde
viation. One‐wayanalysis of variance (ANOVA)was used to iden‐
tify significant differences between the groups. The associations
betwee n variables we re assessed by Sp earman's correl ation coef‐
ficient. Significance was determined at p < .05.
3 | RESULTS
3.1 | Effect of 1‐MCP and ETH on postharvest
senescence of Z. latifolia during storage at 25°C
The major symptoms of postharvest senescence of Z. latifolia are
shell etiolation, surface browning, transpiration, respiratory disor
ders, and tissue hollowness. Therefore, we assessed color change,
weight loss, respiration rate, and ultrastructure to evaluate the ex
tent of postharvest senescence of Z. latifolia in this study.
AsshowninFigure1a–c,theL,−a*, and b* values increased rap
idly in the CK Z. latifolia samples during Day 6 of storage at 25°C.
1‐MCPtreatmentreducedtheratesofincreaseintheL,−a*, and b*
valuescomparedwiththecontrol.ETHtreatmentenhancedthein‐
crease in the L value during the first three days of storage but atten
uatedtheincreaseduringtheremainderofthestorageperiod.Also,
a* and b*valueswere lower in theETH treated than thecontrol
samples throughout the storage period.
Figure 2a shows that the respiration rate of Z. latifolia in the con
troldecreasedwithincreasingstoragetime.1‐MCPtreatmentinhib
itedrespirationthroughouttheexperimentalperiod,whereasETH
treatment strengthened respiration during the first 3 days of storage
compared with the control.
Weight loss occurred continually throughout the storage period
in all samples, particularly the control, which showed a weight loss of
approximately 14.91% by the end of storage (Figure 2b). Compared
withthecontrol, both the 1‐MCPandETHtreatmentssignificantly
(p < .05) inhibited the weight loss over 6 days of storage, with the
greatestinhibitionfoundinthe1‐MCP‐treatedsamples.
AsshowninFigure3a,thecellstructureofZ. latifolia in the con
trol samples was intact with a clear cell wall, a nucleus, and abundant
mitochondria at the beginning of storage.After6 days ofstorage,
changes in cell structure occurred in the control samples. The cell
wall appeared to have dissolved, with no clear boundary, and a part
of the cell wall remained only as an outline (Figure 3b). In addition,
FIGURE 1 Effectsof1‐MCPandETHontheL, a*, and b* values
of Z. latifolia during storage at room temperature (25°C). Vertical
bars indicate the standard errors of three replicates
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apparent swelling deformation of the mitochondria was observed,
causing the mitochondria to disappear. These observations sug
gested that the cell structure of Z. latifolia in the control was signifi
cantly degraded.1‐MCPand ETHtreatmentssignificantly (p < .05)
retarded and promoted the degradation of cell structure in Z. latifo
lia.In1‐MCP‐treatedsamples,thecellstructurewasrelativelyintact
and the cell wall, plasmodesma, and mitochondria were clearly visi
ble, although the number of mitochondria had decreased (Figure 3c).
However,inETH‐treatedsamples,severedissolution wasapparent
in the cell wall after 6 days of storage and a part of the cell wall
was fractured (Figure 3d). Furthermore, mitochondria were no lon
ger readily discernable and those observed exhibited severe swelling
and deformation or even degradation.
3.2 | Proteomic profiles by iTRAQ combined with
2D‐LC‐MS/MS
Total proteins extracted from the seven Z. latifolia mitochondrial
sample s with three biolo gical replicat es were analyzed by i TRAQ
labeling combined with 2D‐LC‐MS/MS . A total of 1,390 protei ns
were identified from 43,532 MS/MS spectra and 15,639 peptides,
usinga1%globalfalsediscoveryrateand≥2uniquepeptidesasthe
cut‐offs.Aproteinwasconsidereddifferentiallyexpressedifithad
afold change≥2.0 andap < .05 for at least one storage time point
comparedwiththecontrolatDay0(CK0).Basedonthesetwocri‐
teria, 211 DEPs were identified in Z. latifolia mitochondria, including
80DEPs(76up‐and4downregulated)inCK3,109(77up‐and32
downregulated)in 1‐MCP3,102(66up‐ and 36downregulated)in
ETH3,98(87up‐and11downregulated)inCK6,111(102up‐and9
downregulated)in1‐MCP6,and94(76up‐and18downregulated)in
ETH6(Figure4andSupportingInformationFigureS1).Thedetailsof
these DEPs are listed in Table 1.
3.3 | GO annotation and KEGG pathway
analysis of DEPs
To gain a better underst anding of the newly discovered DEPs, GO
annotation was performed using DAVID 6.8 (http://david.abcc.
ncifc rf.gov/) at each time point and the DEPs were categorized ac
cordingtotheirBPsandMFs.TheGOannotationsoftheDEPsare
shown in Supporting Information Table S1. The top 10 enriched
GO terms within each major functional categor y are shown in
Suppor ting Information Table S2 and Figure S2. The GO analysis
yielded377BPand136MFtermsenrichedinCK3,444and148
inETH3, 363and165in1‐MCP3,537and164in CK6, 692 and
234inETH6,and549and180in1‐MCP6(SupportingInformation
Table S1).
Thetwo most enrichedBP terms were single‐organismmet
abolic process (56%) and single‐organism biosynthetic process
(19%) followed by small molecule metabolic process, organic acid
metabolic process, and cellular amino acid metabolic process
(Suppor ting Information Table S2). The most enriched MF terms
were catalytic activity (57%), cofactor binding (13%), and lyase
activity (8%). The most significantly (p<.05)enrichedBPterms
inboththe1‐MCP‐andETH‐treatedgroupswereorganonitrogen
compound metabolic process and cy toplasm. The most signifi
cantly ( p<.05)enrichedMFtermsinthe1‐MCP‐andETH‐treated
groups were copper ion binding and anion binding, respectively,
indicating that these functional categories are important in post
harvest senescence of Z. latifolia.
KEGG analysis of the DEPs was conduc ted to identify the biolog
ical pathways associated with posthar vest senescence of Z. latifolia
(Suppor ting Information Figure S3 and Table S3). The results indi
cated that 25, 20, 32, 24, 30, and 19 KEGG pathways were signifi
cantly ( p<.05)enrichedintheCK3,E TH3,1‐MCP3,CK6,ETH6,and
1‐MCP6treatments, respectively compared with CK0 (Supporting
Information Table S1). The 10 most enriched KEGG pathways in
Z. latifolia mitochondria during storage at 25°C were metabolic
pathways, biosynthesis of secondary metabolites, biosynthesis of
amino acids, biosynthesis of antibiotics, carbon metabolism, carbon
fixation in photosynthetic organisms, 2‐oxocarboxylic acid metab‐
olism, arginine biosynthesis, alpha‐linolenic acid metabolism, and
glyoxylate and dicarboxylate metabolism. Compared with CK0,
1‐MCPtreatmentresultedinsignificant(p < .05) enrichment of DEPs
involved in t he tricarbox ylic acid (TCA ) cycle, pentose ph osphate
pathway (PPP), alanine, aspartate and glutamate metabolism, valine,
leucine and isoleucinedegradation, and C5‐branched dibasic acid
metabolicpathways;andETHtreatmentresultedintheenrichment
ofDEPsassociatedwithoxidativephosphorylation(OXPHOS),PPP,
glycine, serine and threonine metabolism, and phenylalanine, tyro
sine, and tryptophan biosynthesis pathways. Therefore, changes in
these pathways may be closely related to postharvest senescence
of Z. latifolia.
FIGURE 2 Effectsof1‐MCPandETHontherespiratoryrateof
Z. latifolia during storage at room temperature (25°C). Vertical bars
indicate the standard errors of three replicates
    
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LUO et aL.
3.4 | Validation by targeted MS protein analysis
TovalidatetheiTRAQresults,weselectedsixDEPs—citratesyn
thase(no.10),malatedehydrogenase(no.11),6‐phosphogluconate
dehydrogenase (no. 17), peroxidase (no. 49), lipase class 3‐like
(no. 132) and cinnamate‐4‐hydroxylase (no. 157)—for examina‐
tion by PRM . Among these prote ins, citrate synt hase and malate
dehydrogen ase are related to t he TCA cycle, 6 ‐phosphoglu conate
FIGURE 3 Effectsof1‐MCPandETHonthecellultrastructureofZ. latifolia before and af ter 6 days of storage at room temperature
(25°C)
FIGURE 4 Effectsof1‐MCPandETHonthemitochondrialproteomeofZ. latifolia during storage at room temperature (25°C)
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TABLE 1 Differentially expressed proteins in Z. latifolia mitochondrial after 3 and 6 days of storage as compared with control at day 0
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
Tricarboxylicacidcycle(TCA)
1Q9ASP4 Dihydrolipoyl dehydrogenase 37. 9 37. 92 69. 8 25 0. 8710 0.51 52 0.1871 1.3428 1.2 474 0.8872
2Q10S3 4 Aconitatehydratase 57. 19 57. 17 53.6 44 0.9727 0.6792 0.0619 1.4322 1.4191 1.2023
3Q9SDG5 Isocitratedehydrogenase[NAD]subunit 1 7.9 1 18. 01 52. 5 19 1. 076 5 0.7047 0.3802 1. 5136 1. 3062 1 .2246
4Q7XMA0 Isocitratedehydrogenase[NADP] 36.83 36.84 59. 4 20 1.0864 0.9 376 0 .4169 1.2589 1.3552 1.367 7
5Q6YZX6 Putative aconitate hydratase, cytoplasmic 26.21 42.06 44 29 1.0864 0. 8241 0.2270 1.3183 1.4191 1 .0375
6Q6Z5N4 PyruvatedehydrogenaseE1componentsubunitalpha‐1 33.56 33.6 62.6 33 1.10 66 0.4285 0. 2754 1.8365 1 .70 61 1.1695
7Q94JA2 Malate dehydrogenase 35.88 35.9 77.9 47 1.1 272 0. 6792 0 .100 9 1. 1376 1 .1272 0 .9817
8Q6ZI55 NAD‐dependentisocitratedehydrogenasec 19.7 9 19.83 4 7. 4 18 1.2134 0.751 6 0.2333 1.4454 1.4723 1.367 7
9Q6F361 Malate dehydrogenase 11.7 8 32.34 72.1 41 1.4191 0.8 872 0.14 32 1 . 5276 1.5704 1.0864
10 Q6EUF8 Citratesynthase(unknownstereospecificity) 24.46 24. 48 35.4 20 1 .9231 0. 5445 0.2032 1 .5417 1 .5417 0.6486
11 Q42972 Malate dehydrogenase, glyoxysomal 20.68 23.69 64 18 2.2284 1.0666 0.5916 2.0893 2.4889 1.14 82
Pentose phosphate pathway (PPP)
12 Q84ZL6 Os08g0154300 protein 18.47 18.53 35.8 10 0.5808 0.6026 0 .4571 0.6982 0.8395 0.70 47
13 Q6YZC3 Glucose‐6‐phosphate/phosphatetranslocator 2.82 2.94 10.9 21.8030 2.6062 1 .9055 2 .2491 3.4356 1.9770
14 Q2R480 6‐phosphogluconatedehydrogenase,decarboxylating2 17. 6 8 23.85 37. 6 14 1.8535 1.7865 1.3932 2.0701 2.8054 2.0137
15 Q65X97 Os05g0524400 protein 21.52 21.55 2 9. 8 11 1.94 09 2 .53 51 1.9409 1.70 61 2.0 512 1 .556 0
16 Q6ZEZ2 Os07g0176900 protein 10.62 10.66 35 82.3121 2.3988 1.4191 2.7797 3.94 46 2.9923
17 Q9LI00 6‐phosphogluconatedehydrogenase,decarboxylating1 28.26 28 .31 48.8 15 2.3335 1.51 36 1.1 376 2.466 3. 46 74 1.4060
18 Q5JK10 Os01g0926300 protein 2 7. 42 27. 49 6 4.1 19 2.3335 2.5823 0.912 3.3113 4.3652 3.1623
19 Q6YXI1 Glucose‐6‐phosphateisomerase 39.34 39.36 61 .8 24 2 .9107 3.3113 1 .8197 3.6308 5.3456 4.16 87
20 Q94JJ0 Fructose‐bisphosphatealdolase 22.58 2 2.61 3 7. 6 16 3. 047 9 3.281 3.02 3.4356 5.754 4 3.10 46
21 Q0DEU8 Os06g0133800 protein (Fragment) 12.92 13.09 19. 2 73.1333 3. 2211 1 .9231 4.0179 5. 8076 2.9 923
Respiratoryelectron‐transportchainandoxidativephosphorylation
22 Q7G3Y4 ATPsynthasegammachain 21.45 21. 52 47. 2 14 0 . 515 2 0.113 8 0.9036 1.0965 0.7727 0. 5649
23 Q7XXS0 Os08g 0478200 protein 10.17 10.53 42 60 . 515 2 0. 2249 1.0666 1 .0 765 0 .74 47 0 .4169
24 Q6ZG90 ATPsynthase 18.89 18.97 46.7 36 0.6026 0.4093 0.8 551 0.8630 0.6 855 0.5808
25 Q7XZW1 NADH‐ubiquinoneoxidoreductase23kDasubunit,puta‐
tive, expressed
10.95 10.99 34.1 80.6194 0.4529 0.8630 0.8 551 0.6855 0.8166
26 Q0DI31 Cytochrome c 55.11 45.5 40 .631 0 .2679 0.136 8 0.9120 0.8 091 0.3532
27 Q9S827 Succinatedehydrogenase[ubiquinone]iron‐sulfursubunit1 20.3 20.31 48.8 20 0.7727 0. 520 0 0.4571 1.0666 0.955 0.7244
28 Q0DG48 ATPsynthasesubunitbeta 71 .06 71 .05 76 . 8 182 0.7943 0.1355 0 .9638 1.2359 0. 8 551 0.8954
29 Q35322 NADHdehydrogenase[ubiquinone]iron‐sulfurprotein3 21.71 21.73 69.5 14 0.8 017 0.4365 0.8472 0.9638 0.8241 0.8472
(Continues)
    
|
 9 of 20
LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
30 Q6K6A4 Os02g0816800 protein 22.57 22.73 37. 8 19 0.8166 0.4 699 1.10 66 1 .13 76 0.8710 0.4 875
31 Q8W317 NADH‐ubiquinoneoxidoreductase75kDasubunit,puta‐
tive, expressed
42.08 42.08 51 .8 40 0. 8241 0.4699 0 .9462 1 .0375 0.8472 0 .8 472
32 Q5VR12 NADH‐cytochromeb5reductase 14 .81 14. 87 45.7 90 . 85 51 0.3837 0.2805 1.3183 1.2359 0.6 427
33 Q8H2T7 Os07g0645400 protein 32 .69 32 .98 54.8 29 0.8710 0.4699 0.9638 1.1169 0.9817 0.7178
34 Q75LJ3 Electron transfer flavoprotein subunit alpha 12.78 12. 87 38.8 71.0093 0.7656 0.3532 1.6293 1.5849 1.4997
35 Q6ZDY8 Succinatedehydrogenase[ubiquinone]flavoproteinsubunit 34.14 3 4.15 4 9.4 43 1.0666 0. 51 52 0.3908 1.1695 1.0666 0.963 8
36 Q6ZGJ8 Putative inorganic pyrophosphatase 20. 21 20.29 48.3 12 1.2589 1.4454 0.8954 1.7378 2.0 324 1.4723
37 Q7F9U3 Electron transfer flavoprotein subunit beta 10.3 10 .47 43.1 71.3804 0.9727 0.3981 1.7378 1 . 6749 1.556 0
38 Q7DNB0 ATPsynthasesubunitalpha 26. 63 34.98 51.5 19 2 .4210 3 .8 019 4.1687 2.3550 5.6494 3.9811
39 Q8L6I1 Os12g0638700 protein 34.86 57. 3 2 46.3 42 2.5823 2 .2284 1 .9770 2.3988 1. 5704 1.6293
40 P12085 ATPsynthasesubunitbeta 3 3.47 42.91 65 .1 28 5.1051 6.6 069 4.5709 4.13 05 8.0168 5 . 5976
41 Q0J9F5 Os04g0656100 protein 59.96 59.9 7 46.3 53 12 .473 8 10.5682 11. 376 3 15.9956 12.0226 8.9536
Reactive oxygen species (ROS) metabolism
42 Q2RAP0 l‐galactono‐1,4‐lactonedehydrogenase1 8.97 9.18 21.8 60.6310 0 .3837 0.5916 0.70 47 0.7178 0.7516
43 B7EA73 Puromycin‐sensitiveaminopeptidase 7.3 4 7.47 11.1 40.6668 0.62 52 0.3597 0.7943 0.8395 1.0280
44 Q9SDD6 Peroxiredoxin‐2F 4.63 4.71 32.3 20. 8241 0 .6310 0.1213 1.1482 1.0864 0 .9638
45 Q0IM09 Sulfurtransferase 20.68 20.75 40.3 12 0.9036 0.7244 0 .160 0 1.1912 1.3305 1. 0765
46 Q5Z8H5 Peroxidase 7.97 8.05 31.8 51 .1376 2.3335 2.2284 0.6607 1.018 6 0.8166
47 Q43008 Superoxidedismutase[Mn] 10.18 10.24 62. 8 12 1.18 03 0.8017 0.1202 1.8880 2.0893 1.2823
48 Q8S5T1 Glutathione reductase, putative, expressed 10.2 5 10.4 2 7. 2 71.9231 1.69 04 1.3428 2 .1677 2 .4210 2 .1281
49 Q6AV Z8 Peroxidase 6.11 6.12 21.6 31.9770 3. 4041 6.7298 0.6368 0. 520 0 1. 614 4
50 Q0D9C4 CatalaseisozymeB 22.46 22.62 50.2 21 2.0137 0.5702 0.3945 2.0 893 2. 3768 0.8630
51 Q6ER94 2‐CysperoxiredoxinBAS1 15.26 15.29 52 .5 13 4.0926 4.4463 2.6 062 4.4055 6.3680 3. 7670
52 Q0J3N7 Superoxidedismutase[Cu‐Zn] 10.86 11.89 50.2 11 4. 2855 3 .8 019 1. 3428 5. 3456 6.9823 5.9704
Programmed cell death
53 Q6H450 AnnexinV 16 .55 16 .59 28.6 84.1305 4.4 055 3.6644 4.9659 4. 2855 3 .944 6
Protein biosynthesis and degradation
54 Q6Z7F0 PutativeATP‐dependentClpproteaseATP‐bindingsubunit
ClpX1 (CLPX)
4.16 4.19 1 7. 3 40.3 251 0.4285 0. 2938 0. 3597 0.4446 0.7244
55 Q0ILZ4 DEAD‐boxATP‐dependentRNAhelicase9 8.44 8.64 18.8 50.4786 0.3565 0. 2655 0.3532 0.4406 0. 2858
56 Q6Z8F7 26Sproteosomeregulatorysubunit‐like 20.48 21. 22 30.8 11 0.520 0 0.3499 0 .5152 0 .7656 0 . 5152 0.8 091
57 Q84PB3 Eukaryotictranslationinitiationfactorisoform4G‐1 13.91 14. 33 20.6 70 .6138 1.0568 1.018 6 0.5248 0.6081 0 .4 613
(Continues)
TABLE 1 Continued
10 of 20 
|
   LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
58 Q6YU81 Putative ribosomal protein S5 10.49 10.65 1 9.8 50.6486 0. 2489 0.55 46 0.8091 0 .6918 0.5495
59 Q7XZF7 ProbableDNAgyrasesubunitA 25.75 25.8 23.5 13 0.6668 0.4285 0.4613 0.9638 0.912 0 1.2589
60 P92812 60S ribosomal protein L2 20.12 20.26 3 8.1 11 0.6668 0.3373 0.4966 0.9638 0.7112 0.8 395
61 Q75IT2 Putativepentatricopeptide(PPR)repeat‐containingprotein,
PF01535
12.86 12.99 12.8 70.70 47 0.4 487 0. 3597 0.6792 0 . 58 61 0.7178
62 Q6ZJS7 Elongation factor Ts 11.24 11. 28 20 60.8166 0.6 081 0.1294 1 .13 76 1.1272 0.9204
63 Q851Y8 Elongation factor Tu 29.4 2 2 9.4 4 58.3 26 0.8395 0. 5916 0.1 271 1.0093 1.0000 0.6982
64 Q53JB5 Putative uncharacterized protein 10.69 10.8 28.9 20. 847 2 0. 8241 0 .5598 0.3192 0. 4571 0. 6792
65 Q6H4L2 Elongation factor 2 61. 2 61.19 60.6 43 0.9036 0. 8017 1.1376 0.4831 0 .41 30 0.5495
66 Q6ASU8 Putative translational activator 53.98 54.03 20.3 28 1 .0 471 1.8707 1.14 82 0. 5297 0.6486 0. 4130
67 Q10QZ6 Elongationfactor1‐alpha 29.38 2 9.41 57. 7 34 1.1695 1. 513 6 1.8535 0.6546 0.70 47 0.4246
68 Q6ZLK0 Dolichyl‐diphosphooligosaccharide‐‐proteinglycosyltrans
ferase48kDasubunit
14.17 14.33 41 15 1.6444 2.1478 1. 5 417 0.9817 0.9638 0. 613 8
69 P35683 Eukaryoticinitiationfactor4A‐1 44.34 44.38 70.5 41 1. 70 61 2.2699 1.9588 0.8318 1.2474 0.9550
70 Q6Z7B0 Dnak‐typemolecularchaperoneBip 32.83 38.99 47. 2 26 2.0893 2.0324 1.2823 1. 6596 1.19 12 0.9290
71 Q6ZI53 Elongation factor Tu 17. 4 6 18 .59 40.5 12 2.2491 2. 0324 1.2359 2.5586 3. 8726 2.93 76
RNAdegradation
72 Q8H3I7 10kDachaperonin 9.7 3 9.91 75.5 40.8872 0. 6252 0.0938 1. 367 7 1.3062 1.0000
73 Q0E3C8 ChaperoneproteinClpB3 25.37 30.58 28.5 14 1.0000 0.6607 0.2333 1.2823 1. 4191 1.4454
74 Q6ZFJ9 60kDachaperoninbetasubunit 17. 6 2 41. 56 56 27 1.5849 1. 5417 1 . 2474 1 .690 4 2.1478 1.5276
75 Q7X9A7 60kDachaperoninalphasubunit 14.59 32. 55 48.1 30 1.9770 2.0701 1.556 0 1.9055 2.75 42 2.0137
76 Q7F9I1 Chaperone protein ClpC1 78.58 78.58 61 .6 52 2.2284 2 .3121 1.5996 2 . 376 8 3.49 95 2.3988
77 Q2QU06 60kDachaperoninalphasubunit 37. 9 1 39. 8 6 55. 2 31 2.3550 2.1677 1.4191 2 .1878 3.5318 2 .3768
78 Q69QD5 Chaperonin 5.16 11.54 32.7 64.4 055 5.1051 3.0479 4.9659 5 .8614 4.1305
Hydrolaseactivity
79 Q5Z974 ATP‐dependentzincmetalloproteaseFTSH1 19. 49 19.9 8 25.1 10 1.3305 1.8365 1.8880 1.6293 2.9107 2 . 8576
80 Q655S1 ATP‐dependentzincmetalloproteaseFTSH2 26.4 28.45 39. 2 15 1. 5560 2.1478 2.2080 1.6749 3.0 479 2.9107
81 Q6Z505 ATP‐dependentClpproteaseproteoly ticsubunit 7. 6 7.74 40.7 42.2909 2.3768 1.7539 2.6546 3 .4995 2.4 889
Aminoacidmetabolism
82 P93438 S‐adenosylmethioninesynthase2 9.4 4 9. 49 16.8 50.6081 0 .5297 0.6486 0.3945 0.4571 0.4207
83 Q7Y1F0 Serine hydroxymethyltransferase 32.87 32. 87 61.9 70 .6855 0. 3 076 0.0895 0.7798 0.7727 0.5702
84 Q6ZCF0 Probablegamma‐aminobutyratetransaminase3 13.22 22 .52 4 7.7 18 0.6918 0.5346 0.1259 0 .8 551 0 .76 56 0 .70 47
85 Q10R45 Alanine‐glyoxylateaminotransferase2,putative,expressed 21. 61 21.64 46.7 13 0.7798 0.4 656 0.155 6 0.8017 0.7178 0.6546
86 Q6V9T1 Glycine dehydrogenase P protein 4 0.14 40.16 45.9 33 0.7798 0.5012 0.3048 0. 8017 0.7178 0. 6792
(Continues)
TABLE 1 Continued
    
|
 11 of 20
LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
87 Q850X1 Putative isomerase 7.54 7. 6 6 30.5 50.8790 0. 5395 0.1803 0.7943 0 .7178 1.2942
88 Q10G56 Ornithine aminotransferase 9.6 4 9. 75 34 80 .920 4 0.6252 0.1459 1.2706 1.3552 1.0965
89 Q6L5I4 Putative aldehyde dehydrogenase 13.04 13.1 2 7. 3 60.9638 0. 8395 0.4018 1.4 322 1.3552 1.2942
90 Q7X7S9 Putative alanine aminotransferase 28.42 28 .47 45.7 18 1.0186 0.7047 0.0525 1.7 061 1.556 0 1.0965
91 Q852M0 Glutamate dehydrogenase 23.37 23.45 5 7. 4 16 1.0471 0.8710 0 .3076 1.59 96 1.4322 1.3062
92 Q75IM9 Isovaleryl‐CoAdehydrogenase 23.42 23.46 51 .6 17 1.1169 0 .7311 0.1995 1.6444 1.51 36 1.6144
93 Q7XN11 Gamma‐aminobutyratetransaminase1 29.8 4 29.8 9 52.7 20 1.2023 0.7311 0.0433 1.4859 1.3428 1 .2134
94 Q67UZ0 Aminotransferase 14. 22 14.31 36.3 81.2246 0.6486 0.19 23 1.4322 1. 5136 1.4588
95 Q0INQ6 Serine hydroxymethyltransferase (Fragment) 13.81 13.9 25.3 27 1.4322 1 .0965 1.1 376 1.9231 2.2284 1.7701
96 Q0JPA8 Histidinoldehydrogenase 12. 76 12.84 28.1 81.4 454 1.224 6 1.3 062 1.97 70 2. 4210 1.8030
97 Q5VNW0 3‐phosphoshikimate1‐carboxyvinyltransferase 16.66 16.77 39. 2 12 1 .5136 1.6596 1.0375 1.94 09 2.884 1 .4723
98 Q2QXY9 2‐isopropylmalatesynthaseB,putative,expressed 32.65 32.72 44.9 21 1.5560 2 .1281 1.2246 2.6062 3.7325 2.9107
99 Q6KA J2 Aspartateaminotransferase 32. 74 32.79 60.3 24 1.7378 1.5996 1.1169 2 .1478 2 .729 1. 674 9
100 Q67W99 PutativeD‐3 14.31 16 .35 22.1 10 1.7865 2.1281 1.4191 1. 8197 2 .8314 2. 2284
101 Q69RJ0 Ferredoxin‐dependentglutamatesynthase 65.48 65.45 35.9 31 1.9953 2.2080 1.5849 2.4889 3 .3113 2.6062
102 Q10R10 Hydrolase,carbon‐nitrogenfamilyprotein,expressed 15.24 15.26 38.4 82.0701 1.7701 0 .7656 2.9 923 2.8054 3.0200
103 Q10NW0 ImidazoleglycerolphosphatesynthasehisHF,putative,
expressed
22.88 22.94 38.7 17 2.0701 2.1677 1.674 9 2. 8314 3.5318 3.0200
104 Q7Y096 3‐isopropylmalatedehydrogenase 20.35 20.37 40.4 14 2.0893 1.94 09 1. 4723 2 .1677 3.020 0 2.4660
105 Q688Q9 Glutamate‐‐cysteineligaseA 16.69 16.78 33.9 10 2.2080 2.228 4 1.3305 2.3988 3.4 041 2.4889
106 Q5Z9H5 Putative arogenate dehydrogenase isoform 2 16.63 16.68 34.6 92.6062 2.4660 1. 6596 2.729 5.0582 3.5975
107 Q67VM2 Putative Tryptophan synthase beta chain 9.5 5 9. 69 23.1 62.7290 3.4 674 1.9409 4 .2855 5.6494 3.56 45
108 Q8LMR0 Phosphoserine aminotransferase 22.35 22.45 39 20 2.9107 2. 3768 1. 8707 2.96 48 4.4875 2.4660
109 Q93Y73 Aspartate‐semialdehydedehydrogenasefamilyprotein,
expressed
16.3 4 16.35 4 9.1 20 3 .0761 3. 0479 1.7865 3.8371 5.2000 3.4356
110 Q6H6I1 3‐isopropylmalatedehydratase,smallsubunit‐like 9.3 5 9.4 30.4 73.0761 3.0479 1 .5417 3 .7670 5 . 5976 3.2509
111 Q6Z74 4 Dihydropyrimidine dehydrogenase 23.67 23.72 47. 8 16 4.3652 5.4450 2.3988 9. 036 5 11. 695 7. 3 11 4
112 Q2RAZ7 Alpha‐l‐arabinofuranosidaseC‐terminusfamilyprotein,
expressed
10.5 4 10.71 14.6 76.3680 5. 8076 5.495 4 12.3595 11.5878 10.4713
113 Q7X7N2 Arginase1 11.21 11.37 45.9 80.9638 0 .7178 0.2070 1. 2706 1.1912 1 .1376
114 B9EXM2 Carbamoyl‐phosphatesynthaselargechain 4 8.55 48.55 37 29 1 .180 3 1. 2474 1.1695 1 .70 61 2.0324 1.5704
115 Q6YVI0 Putative ornithine carbamoyltransferase 10. 74 10.78 31.9 10 1.7378 1.7539 1.1588 2.1281 2.7040 1. 8197
116 Q10N79 ArgininebiosynthesisbifunctionalproteinArgJ 12.99 13.03 22 .9 71.9231 1.8707 1 .4859 2.6062 3.4 674 2.2080
117 Q2QVC1 Argininosuccinatesynthase,putative,expressed 29. 6 8 29. 77 47. 2 21 2.4889 2.466 1.8030 3. 047 9 4.0179 2 .7797
(Continues)
TABLE 1 Continued
12 of 20 
|
   LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
118 Q10MK5 Argininosuccinatelyase 18.0 3 18.07 40 .9 11 2.6303 3.5318 2.5823 4 .130 5 5.0119 3. 8019
119 Q10GQ5 N‐acetyl‐gamma‐glutamyl‐phosphatereductase 13.25 13.29 29. 2 11 3 .3420 3.90 84 3 .1623 4 .6132 6.8549 4.1687
Transaminase activity
120 Q5JJI4 Probable mitochondrial import receptor subunit TOM20 11. 61 11.82 46.5 90.0225 0.6252 0.8241 0.6668 0.5058 0.4656
121 Q2QZ12 Mitochondrial carrier protein, expressed 22.18 22.25 56.2 15 1.4997 0.5808 1. 513 6 2.0 512 1. 6596 1.10 66
122 Q6Z229 Putative glutamate/malate translocator 2.9 3. 24 10.6 32.0701 2.3335 1.8030 2. 3550 3 .0 479 1.7539
123 Q5JL23 ABC‐typetransportsystem‐like 6. 57 6.69 24 .6 32.2491 2.2080 2.1677 2.2491 3.3729 2.4210
124 Q6H8E4 PutativeplastidicATP/ADPtransporter 12.33 12 .35 13. 2 82.5586 2 .53 51 2.0893 2 .3121 3 .4 674 1.6444
125 Q6AV V6 Nitrate transpor ter, putative 6.49 6.7 8.5 35.2966 5.3456 4.24 62 4.786 3 4.4 055 3.9 08 4
Lipid metabolism
126 Q2QYF8 Cytidylyltransferase family protein, expressed 21.7 21 .74 41 10 0.4920 0.4 831 0.5 861 0 .74 47 0.6368 0.5970
127 Q9LRI6 MitochondrialaldehydedehydrogenaseALDH2a 22.48 22.55 3 9. 2 19 0. 8241 0 . 515 2 0.4571 0.9908 0.9036 0.8790
128 Q9FRX7 AldehydedehydrogenaseALDH2b 16.74 21.3 43.7 22 1.1695 0.8630 0.4786 1.4997 1.5704 1.4191
129 Q69QJ7 Probable monogalactosyldiacylglycerol synthase 1 10.21 10.31 26 51.6444 1.3552 1.18 03 1.7865 2.2080 1.4322
130 Q10EH4 Lipoxygenase 4.95 8.24 12.7 52.0324 2. 5119 2.2284 1.0666 1.7378 1.18 03
131 Q75IK4 Putative lipase 12.12 13.5 34.4 92.2080 2.6792 3.7325 0.8318 1.1912 1. 2134
132 Q6Z307 Lipaseclass3‐like 10 10 12.2 63. 8371 5.1523 2.7290 4.9204 5.0582 4.4875
133 Q94LR9 3‐ketoacyl‐CoAthiolase2,peroxisomal,putative,
expressed
14.28 18.56 34.7 11 1.0000 0.3664 0.3802 0 .7178 0.7943 0.5395
134 Q10MS3 MalonylCoA‐acylcarrierproteintransacylasecontaining
protein, expressed
15.34 15.39 41. 3 12 1.4060 1.3183 0 .8 017 1.614 4 2. 0137 1.570 4
135 Q5W6W 7 Longchainacyl‐CoAsynthetase 23.42 23.48 30.4 13 1.8707 2 .1677 1.7219 1 .5996 1.7865 1.3183
136 Q84P96 3‐ketoacyl‐CoAthiolase‐likeprotein 33.34 33.38 61.4 36 2. 2491 0.8091 0.4246 1 .9770 2 .0324 0.9550
137 Q69YA2 3‐oxoacyl‐[acyl‐carrier‐protein]synthase 16.07 16.14 38.5 16 2 . 376 8 2.6 062 1.7865 2.5823 3.6644 2.9107
138 Q0JL46 Neutral ceramidase 13.08 13.15 15 86.0813 6.4863 5. 8614 8.3946 7.11 2 1 6.7920
Nucleic acid metabolism
139 Q6KAI0 Polyribonucleotide nucleotidyltransferase 2 15.52 15.6 17. 1 80. 5970 0.51 05 0.4831 0.6668 0.62 52 0.7311
140 Q08479 Adenylatekinase3 23.96 24.01 59. 8 16 0.6918 0.3802 1.0666 1.4997 1.2359 0. 2911
141 Q0DZG1 Succinyl‐CoAligasesubunitbeta 47. 93 47.95 78 35 1.0000 0.7047 0.0525 1. 5560 1 .3677 1.0568
142 Q9LD61 Aspartatecarbamoyltransferase 26.98 27. 0 4 51 13 1. 513 6 1.6749 1. 4191 1.9055 2.3988 2. 4210
143 Q6ZKK5 Putative aminoimidazolecarboximide ribonucleotide
transformylase
15.23 15 .41 4 6.1 10 1.9055 1.888 1.3428 2.1086 2 .9107 2.2284
144 Q10MD1 Adenylosuccinatelyase 7.5 5 7.6 4 23.4 72.1677 1 .8197 1.3552 2.3768 2.8840 2.6062
145 Q5N821 Putative formylglycineamide ribotide amidotransferase 38. 67 38.69 32.2 23 2.9107 2. 6546 2 .1478 3 .2810 4.9659 3.8 371
(Continues)
TABLE 1 Continued
    
|
 13 of 20
LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
146 P37833 Aspartateaminotransferase,cytoplasmic 24.8 6 25.61 58.5 22 3.2509 0.7798 0.4093 3.9811 3. 5975 1. 7219
Organic acid met abolism
147 Q337E9 Malic enzyme 9.51 11 .8 9 29. 5 60.6982 0.5649 0.1528 0 .920 4 0. 8472 0. 8551
148 Q7F19 0 Malic enzyme 37. 0 3 38.93 54.3 28 0 .9120 0.5346 0.3020 1.0000 0.94 62 0.9290
149 Q7XPR2 Aminomethyltransferase 23.44 2 3.47 52 .9 16 0.9550 0. 58 61 0.0581 1.1272 1.0093 1.0 093
150 B9F3B6 Succinate‐semialdehydedehydrogenase 19.75 20.02 42 .7 17 1 .0 471 0. 6310 0 .1419 1.4588 1.3677 1 .1912
151 Q7XI14 ProbableD‐2‐hydroxyglutaratedehydrogenase 16.66 16 .74 26. 8 12 1.0471 0 .7311 0 .1019 1.3804 1. 2942 1.1272
152 Q0DC43 Formate dehydrogenase 17.61 19. 2 7 50 31 1.18 03 0.8 472 0.1019 1. 8197 1. 5417 1.3 677
153 Q0DJT2 Lactoylglutathione lyase (Fragment) 19.9 6 19.9 9 50.2 10 1.7378 1.7378 0.8954 2.1281 2 .9376 2.10 86
154 P0C 51 2 Ribulose bisphosphate carboxylase large chain 25.42 25.49 47 24 2.4660 2.4889 2.0893 3. 2211 4.3652 3.0479
155 Q7XUG1 Malate synthase 10.31 10.49 25.2 48.953 6 5.2000 1.4060 13.42 76 15. 2757 6.0813
Phenylpropanoid biosynthesis
156 Q5VNW0 3‐phosphoshikimate1‐carboxyvinyltransferase 16.66 16.77 39. 2 12 1 .513 6 1.6596 1.0375 1.94 09 2.8840 1. 4723
157 Q5W6F1 Cinnamate‐4‐hydroxylase 19. 5 4 19. 6 6 31.2 82 .108 6 2.7040 1. 8197 2 .1878 2.2699 1.7865
158 Q5ZCV1 Putative dehydroquinate dehydratase 16.46 16.56 52 .5 13 2.7290 2. 2699 1.9231 3. 3420 4.6559 2.8054
Biosynthesisofsecondarymetabolites
159 Q8RU48 Cell elongation protein DIMINUTO, putative, expressed 18.1 18 .16 37. 8 11 0.6855 0.8 872 0.8091 0. 3597 0.42 07 0.3664
160 Q10PQ1 CytochromeP45074A2,putative,expressed 9.14 9. 24 20.3 51.3932 1.6596 2.1478 2.2080 2.4434 1.7865
161 Q75KD7 AOC 8 .74 8.84 32.1 10 2. 0324 1 .940 9 1.4060 1.8707 2.8314 2.167 7
162 Q7XUK6 6,7‐dimethyl‐8‐ribityllumazinesynthase 10.21 10.25 33.9 52.0893 1.9953 1.4322 2 .2491 2.9107 2 .3121
163 Q60EI0 Putative ferredoxin sulfite reductase 13.81 13. 87 39.4 14 2.6546 2.6303 1 .556 0 2.93 76 4. 0 551 3.4995
164 Q6K439 Probableplastid‐lipid‐associatedprotein2 12.29 12.3 33.5 92.9648 3 . 46 74 2.9648 4.9204 7. 0 4 69 5.24 81
165 Q6K 7V6 Probable tocopherol cyclase 9.9 6 10.05 21.1 73. 5975 3. 5975 2 .9376 4.4463 6.0256 4. 6559
Stress response and defense
166 Q53NM9 DnaK‐typemolecularchaperonehsp70‐rice 8.25 50.06 58.9 34 0 . 510 5 0.6 081 0.673 0 0. 4130 0.2992 0.2911
167 Q5Z4M2 Putativemicrotubule‐associatedprotein 10.86 11.14 25.2 80 .5200 0.575 4 0 .4130 0.2655 0 .1419 0.1995
168 Q7XS58 Cysteine synthase 12.05 13.4 3 39. 8 70.6546 0 . 5105 0.0973 0.7727 0.7870 0.6252
169 Q655Y3 Dreg‐2likeprotein 16 .26 16 .31 41 .4 10 0.7311 0.6026 0 .133 0 1.1066 0.9550 0.8091
170 Q0 IN14 Hsp90protein,expressed 32.26 3 2.74 38.4 30 0.7798 0.4207 0.0530 0. 8241 0.8091 0 .6026
171 Q10SR3 70kDaheatshockprotein 8.14 35.43 47.8 33 0. 8551 0.4613 0.0773 1.1272 1.0093 0.9036
172 Q6Z7V2 24.1kDaheatshockprotein 5.91 6.09 20.9 40.9550 0.4966 0.2228 1.0864 1.0 093 0.9908
173 Q10Q21 Mitochondrial processing peptidase beta subunit, putative,
expressed
25.93 25.99 35.8 20 0.9908 0.4446 1.1066 1.367 7 1.0666 0.8630
174 Q6ZL94 Probablesuccinyl‐CoAligase[ADP‐forming]subunitalpha 20.66 20. 87 53.5 16 1.0568 0.7516 0.0535 1. 6596 1.4859 1.1066
(Continues)
TABLE 1 Continued
14 of 20 
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   LUO et aL.
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
175 Q6ZG77 Probable diaminopimelate decarboxylase 17. 3 4 1 7. 37 33.1 81.8030 1.7539 1.18 03 2.1677 3.1333 2.1677
176 Q2QV45 70kDaheatshockprotein 37.1 6 39.2 1 45.3 25 2 . 376 8 2.6303 1 .5 276 2.5586 3.9446 2. 3550
177 Q10MQ2 Probable l,l‐diaminopimelateaminotransferase 33.01 33.02 58.4 22 2.6546 2.6546 1.4588 3.6983 4.8306 3 .767 0
178 Q8L5K0 Ferritin 5.35 5.46 28.6 32 .9 376 2.558 6 2.1878 2.9107 4.0926 3.9811
179 Q7XU28 OSJNBb0034G17.8protein 12.23 12. 41 37. 9 63. 2810 2 . 53 51 1.2474 2.5 351 4.24 62 3.0479
180 Q6ZIV7 Hypersensitive‐inducedresponseprotein 16 .76 22.32 63.7 13 3.6644 3. 2810 2.7542 5. 0119 3.6644 3.2810
181 Q5VS25 Put ative beta 1,3 glucan synthase 18. 29 2 9.67 17. 7 17 4 .32 51 4.3652 3.8726 4. 0179 3 .4 0 41 1.6444
182 Q0JPA6 S alt stress root protein RS1 8.25 8.51 26 .5 57.17 7 9 8.1658 5.6 494 11 .3 763 11. 376 3 7. 51 62
Signal transduction
183 Q67UI5 C2domain‐containingprotein‐like 29. 24 2 9. 27 2 9. 5 16 1 .0 765 0 .9817 1.4060 0.4446 0.6368 0.7870
184 Q10NP2 Calcium‐bindingEF‐handfamilyprotein,putative,
expressed
19.88 20.14 24.4 91.7701 1.556 1.0471 2 .6792 1.8197 1.8535
185 Q5ZBN0 Receptor‐likeproteinkinase1‐like 11.58 12.57 26.2 62.10 86 1.9588 1.7865 2. 83 14 1.6444 2.1878
186 Q69U53 MAP3K‐likeprotein 7.85 7. 9 1 21.4 42.2491 1.8365 1.7701 3.2509 2.5586 1.9231
187 Q851M7 Serine/threonine‐proteinkinase 10.45 10.48 14 .7 52.5823 1.7701 1. 6293 2. 3550 1. 8707 2. 2491
188 Q7XQU7 Probable protein phosphatase 2C 41 12 .81 12.85 31.7 63.0761 2.6303 1.90 55 3. 7670 3.4356 3.1915
189 Q6Z3Y9 Phosphoinositide phospholipase C 6.36 6.44 13.6 63.191 5 2. 8576 2. 4210 3.4995 2.4210 2.6546
190 Q8H4Q9 GTP‐bindingproteinRab6 20.21 22.33 77.9 12 0 .5152 0.7586 0.6982 0.52 00 0 .5395 0.424 6
191 Q53K24 Adenylylcyclase‐associatedprotein 10.3 3 10.65 22.2 50.5495 1.1272 1.0375 0.4093 0.5702 0. 3251
192 Q6ATR5 Mitochondrial Rho GTPase 34. 81 35.12 46.4 26 0.7244 0. 3499 0.9290 0.7943 0.6668 0.7178
Inositol phosphate metabolism
193 Q6Z4E4 Methylmalonatesemi‐aldehydedehydrogenase 23.04 23.11 36.1 17 1.0965 0 .7112 0.1459 1. 5417 1.406 1.3552
Cofactor binding
194 Q0J5J5 G‐boxbindingfactor 21.13 28 .75 61.3 17 0.7586 1.0375 0. 8241 0.6486 0.5058 0. 3133
195 Q10MK9 AMP‐bindingenzymefamilyprotein,expressed 10.42 12.73 1 7. 4 71.2823 0 .4571 0 .5861 1.0000 1.1272 0. 5546
196 Q2R1S1 Harpinbindingprotein1,putative,expressed 5.59 5.66 17 33.56 45 3.2509 3.10 46 4.2462 6.0256 5.0582
Mitochondrial fission
197 Q8W315 Dynamin‐relatedprotein1C,putative,expressed 27. 3 2 27. 5 5 43.5 19 0.8318 0.9204 0.7586 0.5495 0 .44 87 0. 58 61
Protein‐proteininteraction
198 Q84R32 CBSdomaincontainingprotein,expressed 5.86 653.2 11 0.6 427 0.4207 0 .1871 0.7798 0.56 49 0.6368
Unclear functional proteins
199 Q0JLS6 ProteinROOTHAIRDEFECTIVE3 20 .41 20.49 24.1 10 0 .5546 0.9204 0 .5395 0.48 31 0.3873 0.4 875
200 Q5NAB7 PutativeDNA‐bindingprotein 8.73 8.8 10.5 40.5916 0.4786 0.3802 0. 6310 0.54 45 0. 376 7
(Continues)
TABLE 1 Continued
    
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 15 of 20
LUO et aL.
dehydrogen ase to the PPP, lipase class 3‐like to l ipid metaboli sm,
and cinna mate‐4‐hydroxyl ase and peroxidase to p henylpropanoid
biosynthesis. The PRM results were essentially in accordance with
theproteinprofileobtainedbyiTRAQ(Table2).
4 | DISCUSSION
During senescence and quality deterioration of Z. latifolia, a vari
ety of physiobiochemical responses occur, which are influenced
by various internal and external factors via regulation of protein
expression. Therefore, we evaluated the protein profile changes in
mitochondriaandtheeffectsofpostharvest1‐MCPandETHtreat
ments onthemitochondrialproteome using iTRAQtechnique.The
results revealed that 211 of the 1,390 identified proteins were dif
ferentiallyexpressedaccordingtothecut‐offvalues used(2.0‐fold
expression change and p< .05).A functionalanalysisshowed that
these DEPs are involved in a variet y of metabolic and molecular pro
cesses (Table 1), which may be closely related to the postharvest
senescence of Z. latifolia.
The postharvest vegetable is an independent organ free from
metabolic interactions with other plant parts and respiration is
the predominant physiological process that dic tates its shelf life
due to cut‐offof nutrient sources (Li,Li, etal., 2017; Li, Lichter,
et al., 2016). The respiration rate is a measurable indicator of the
metabolicintensityofpostharvestsupplyvegetables.Ahighres
piration rate leads to the consumption of metabolic substrates,
accelerates maturity or senescence, and shortens the shelf life of
vegetables (Li, Lichter, et al., 2016; Wang, Luo, Khan, Mao, & Ying,
2015). In this study, although the respiration rate decreased during
storage, it remained at a high level (148.8 mg CO2·kg−1·h−1) afte r
sixdaysofstorageatroomtemperature.1‐MCPtreatmentsignifi
cantlysuppressedtherespirationrate,indicatingthat1‐MCPde
layed postharvest senescence of Z. latifolia.Theabilityof1‐MCP
treatmenttoreducetherespirationratewasreportedbyArgenta,
Mattheis,Fan,andAmarante(2016)inpearsandLimetal.(2016)
inkiwifruits.ETH treatment had the opposite effecton respira
tory metabolism during the first three days of storage compared
with1‐MCPtreatment.
Respiration in plants involves several pathways, such as the
Embden–Meyerhof–Parnas pathway, TCA cycle, mitochondrial
electron transport, and cytochrome pathway, PPP and glyoxylate
pathway; each pathway has unique biological functions (Li et al.,
2015). The Embden–Meyerhof–Parnas pathway, which oxidizes
glucose to pyruvate, is a basic respirator y pathway followed by
the TCA cycle and cytochrome pathway,which areessential for
energy provision in postharvest fruit s and vegetables during stor
age (Shen et al., 2017). In fruits and vegetables, the PPP pathway
supplies intermediate reaction products. The respiratory meta
bolic pathways of postharvest fruits and vegetables vary during
storage (Li, Lv, Guo, & Wang, 2016). In this study, almost all DEPs
relatedtotheTCAcycle(nos.1–11)andPPP(nos.12–21)wereup
regulated,suggestingthattheactivitiesoftheTCAcycleandPPP
No. ID Protein name Unused Tot a l % Cov Peptides
Fold changes of proteins
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
201 Q6Z1Y4 Nicalin 9.92 10.08 27. 6 81.3183 2.0893 1.9055 1.3305 1.14 82 0 .6855
202 Q6Z233 PutativeuncharacterizedproteinOJ1111_H02.6 3.9 4.19 8.3 51.3932 1.4322 1.7061 1.6444 2.0893 1.8365
203 Q7Y1D0 PutativeuncharacterizedproteinOSJNBa0033P04.10 14.91 15.01 14.6 10 1.94 09 1.9588 1. 6749 2 .7542 2.9107 2.1677
204 Q69IP1 Putative uncharacterized protein P0450E05.1 10.95 11.0 5 39. 7 61.9770 1.8880 1. 674 9 2. 5119 3.2810 2.398 8
205 Q7XKE6 OSJNBb0017I01.8protein 7.2 8 7. 3 7 42 .1 72.0137 3. 46 74 1.6293 1 .9055 2.5823 1.8535
206 Q60E58 Os05g0388600 protein 11.7 12.15 33.1 92 .2491 2.3335 2. 0 512 2 . 5119 3.1623 2 .53 51
207 Q84P62 OSJNBa0087O24.10protein 9.95 9.99 28 .9 52.5119 2.4660 2 . 5119 2 .3550 3.9811 2.9376
208 Q75M01 Os05g0157200 protein 8.97 9. 03 63.5 82.5586 2.6792 2.3335 2.6792 3. 2211 2.6303
209 Q7XVF8 OSJNBb0118P14.7protein 5.53 5.67 27.9 32.558 6 2. 8576 2 .5119 2.5823 4.5709 3 .4674
210 Q7XPW1 OSJNBa0 032F06.20protein 12.82 13.26 15.3 72.7290 3.0200 2.70 40 3.1333 3.40 41 2. 6792
211 Q337M4 Os10g0463800 protein 4.44 4.62 24.7 46.9823 7. 51 62 0.9550 7.2444 11.5 878 10.964 8
Note: ID,DNAfingerprinting;Unused,confidencelevel;Cov,sequencecoverage.
TABLE 1 Continued
16 of 20 
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   LUO et aL.
pathways were enhanced. This is in accordance with the report s
byKan,Wang,Jin,andX ie(2010)andJiangetal.(20 07).However,
the exact functions of this physiological regulation are obscure.
We speculate that changes in respiratory metabolic pathways may
disrupt energy homeostasis, which may be closely related to the
postharvest senescence of Z. latifolia.
The ETC facilitates redox (simultaneous reduction and oxida
tion) reactions that transfer elec trons from a low energy electron
donor (e.g., nicotinamide adenine dinucleotide and flavin adenine
dinucleotide) to an acceptor (e.g., O2), couple this electron trans
ferwithOXPHOS,andtherebyreleasingtheenergythat isusedto
produce ATP(Jonckheere,Smeitink,&Rodenburg,2012).Aghdam,
Jannatizadeh, Luo, and Paliyath, G. (2018) repor ted that sufficient
intracellularATPsupplyandfriendlyextracellularATPsignalingare
crucial for attenuating stresses, delaying senescence, and maintain
ing qualit y in hor ticultural crops postharvest. In this study, 20 DEPs
(nos.22–41)involvedintheETCandOXPHOSwereidentified.Most
of these proteins were slightly downregulated after three days of
storage. 1‐MCPt reatmentret arded this downregulation, whereas
ETHtreatmentsignificantlypromoteditafterthreedaysofstorage.
TheseresultssuggestthatETCandOXPHOSareweakenedleading
toareducedenergysupply.1‐MCPtreatmentisconducivetomain
tain a relatively high level of energy.
TheETCisalsoamajorsiteofprematureelectronleakagetoox‐
ygen,thusgeneratingROSandincreasingoxidativestress(Kirkland
&Franklin,2015).The metabolicstatusofmitochondrial ROS may
play an important role in programed cell death. Xu reported that
10−9 mol/L ROS promote cell proliferation, 10−6 mol/L ROS result
in programed cell death, and 10−3 mol/L ROS cause cell injury and
death, indicating that the ROS status is closely related to posthar
vestsenescence of fruits andvegetables(Xu, 2003). An important
strateg y for plants to respond and adapt to dif ferent biotic and abi
otic stresses is via the regulation of physiological metabolism. Excess
ROS react with cellular components such as proteins, nucleic acids,
and unsaturated fatty acids to cause oxidative damage (Xia et al.,
2016). To minimize this cellular damage caused by ROS, organisms
have evolved a scavenging system composed of antioxidants and an
tioxidant enzymes. The antioxidant enzymes superoxide dismutase,
catalase, peroxidase, peroxiredoxin, and glutathione reductase play
important roles in scavenging ROS (Xu et al., 2016). Of the 11 ROS
proteins (nos. 42–52), seven were related to antioxidant enzymes
and four to nonenzymatic antioxidant s. In this study, the significant
upregulation of these DEPs suggested that mitochondria are under
increased oxidative stress caused by ROS. This result was validated
by the visualization of the cell ultrastructure by transmission elec
tron microscopy (Figure 3).
Annexins are found mostly in eukaryotic organisms includ‐
inganimals,plants, and fungi. Among these proteins, Annexin V is
commonly used to detect apoptotic cells based on its abilit y to bind
tophosphatidylserine,a marker of apoptosis when located onthe
outer leaflet of the plasma membrane (Donnelly & Moss, 1997). In
thisstudy,Annexin V (no.53)was significantlyupregulated during
storage,especiallyinthecontrol,anditslevelincreasedby4.13‐and
4.97‐fold after three a nd six days of storage , respective ly.A s ex‐
pected,the1‐MCPandETHtreatmentsinhibitedandpromotedthe
upregulationofAnnexinVduringsixdaysofstorageperiod.
Respiratory metabolism, which provides the energy required for
plant biochemical processes, also supplies a number of intermediate
products for synthesis of proteins, amino acids, fats, nucleic acids,
andsecondarymetabolites(Kiprovskietal.,2018).Inthisstudy,we
identified 28 DEPs (nos. 54–81) related to protein biosynthesis and
degradation, 38 DEPs (nos. 82–119) related to amino acid metab
olism, 13 DEPs (nos. 126–138) related to lipid metabolism, 8 DEPs
(nos. 139–146) related to nucleic acid metabolism, 10 DEPs (nos.
188–200) related to organic acid metabolism and 7 DEPs (nos. 159–
165) related to biosynthesis of secondary metabolites. Only 6 of the
18 DEPs related to protein biosynthesis were upregulated compared
with 9 of the 10 DEPs related to protein degradation, indicating that
TABLE 2 TargetedproteomicsdatavalidationbyPRMandcomparisonwithiTRAQproteomicsdata
Proteins Data sources
Fold changes
CK3 ETH3 1‐M CP3 CK6 ETH6 1‐ MCP6
Citrate synthase iTRAQproteomicsdata 1.9231 0.54 45 0.2032 1. 5417 1. 5417 0.6486
PRM validation 1.9229 0.6145 0. 2473 1.8807 1.6 496 0.4828
Malate dehydrogenase iTRAQproteomicsdata 1.1272 0.6792 0.10 09 1 .1376 1.1272 0.9817
PRM validation 2.5791 1.16 00 0.4356 1.70 61 2.140 3 0.7969
6‐phosphogluconate
dehydrogenase
iTRAQproteomicsdata 2.3335 1. 513 6 1.1376 2.466 3 .4 674 1.4060
PRM validation 2.3242 1.4035 0. 8353 2.5379 3.6580 1.4040
Peroxidase iTRAQproteomicsdata 1.9770 3.4 041 6.7298 0.6368 0 .520 0 1.614 4
PRM validation 1.7345 3.1527 5.3949 0.750 5 0.6287 1.0357
Lipaseclass3‐like iTRAQproteomicsdata 3.8 371 5.1523 2.729 4.9204 5.0582 4.4875
PRM validation 4.6290 5.9245 3.0 435 6 .5110 8.7180 3.5652
Cinnamate‐4‐hydroxylase iTRAQproteomicsdata 2.1086 2.70 40 1.8197 2.1878 2.269 9 1.7865
PRM validation 2.10 61 2.530 0 1. 8319 2.0611 2 .3757 1.0436
    
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 17 of 20
LUO et aL.
protein catabolism was enhanced in Z. latifolia during ambient stor
age. The majority of DEPs related to amino acid, lipid, nucleic acid,
and organic acid metabolism and biosynthesis of secondary metabo
lites was upregulated during storage. This may reflect the increased
consumption of substrates for the biosynthesis of cellular compo
nents to maintain normal physiological functions in Z. latifolia during
storage.
Interestingly,1‐MCPreducedthedegreeofup‐anddownreg
ulation of the majority of material metabolism‐related DEPs but
dramatically promoted the upregulation of lipoxygenase (no. 130),
lipase (no.131),and cytochrome P450 74A2(no. 160) after three
days of storage. Lipases catalyze the hydrolysis of fats (lipids).
Polyuns aturated fat ty acids (18:3 and 16:3) are conver ted to cis‐
(+)‐12‐oxo‐phytodienoicacid(OPDA) and dinor‐12‐oxo‐phytodien
oicacid (dn‐OPDA)bythe consecutiveactionsofplastid‐localized
lipoxygenase,allene oxidesynthase,alleneoxidecyclase,and 12‐
oxo‐phytodienoic acid reductase, theninto OPDAbyalleneoxide
cyclase and thenintojasmonicacid (JA) afterthreecyclesof β‐ox
idation (Delker et al., 2006). JA andits metabolites arecrucialfor
plantgrowth,development,and defense. Based on theseresults,
we hypothesize that postharvest senescence of Z. latifolia may be
related to enhanced biosynthesis of JA. This hypothesis awaits
confirmation.
Plant cell walls, which are composed of three major organic
compounds (cellulose, hemicellulose, and lignin), are crucial for pro
viding support and shape to many cell types, forming the interface
between adjacent cells, as well as resisting invasion by pathogens
(Delkeretal.,2006).Inthisstudy,severalligninbiosynthesis‐related
proteins, including 3‐phosphoshikimate 1‐carboxyvinyltransferase
(no.156),cinnamate‐4‐hydroxylase(no.157),andputativedehydro
quinate dehydratase (no. 158), were upregulated in the mitochondria
of Z. latifolia during storage. These results are consistent with our
previous observations that the lignin content increased significantly
(p < .05) and cellulose content increased slightly during storage (Luo,
Jiang,Zhang,Jiang,&Yu,2012).
Unlikeprimary metabolites,secondarymetabolitesare organic
compounds that are not directly involved in the normal growth,
development or reproduction of an organism. The absence of sec
ondary metabolites does not result in immediate death, but rather
inalong‐term impairmentoftheorganism's survivability,fecundity
or esthe tics, or perhap s in no significant ch ange at all (Kiprovski
et al., 2018). Furthermore, stress response and defense, which are
mediated by profound alterations in gene expression, modulate the
plant transcriptome, proteome, and metabolome. In a recent study,
aproteomicanalysisusing2‐DE/MSofthemitochondriafrompe ach
fruits during senescence was performed and differences in the ex
pression of cytoskeleton‐related proteins (e.g., actin and keratin)
were obser ved (Wu et al., 2016). In this study, seven DEPs (nos.
159–165) related to the biosynthesis of secondary metabolites and
17 DEPs (nos. 166–182) related to stress response and defense were
identified. The vast majority of these proteins were upregulated
during storage in the control treatment, suggesting that they play a
role in postharvest senescence of Z. latifolia.
Signal transduction begins with the binding of specific ligands
to receptors located on the sur face of the plasma membrane, re
sulting in alterations in intracellular metabolism (Jiang et al., 2015;
Luo, Li, Du, & Mou, 2015). Li and Xue (2010) reported that the Ca2+,
cyclic guanosine monophosphate, and MAPK signaling cascades
function downstream of hydrogen peroxide signaling. Ca2+ medi
ates signal transduction in plants and depends on a sensor to con
vey changes in its concentration. The main types of proteins that
bind Ca2+ and confer Ca2+‐mediated responses are EF‐hand and
C2‐domain proteins (Reddy & Reddy, 200 4). Protein kinases and
protein phosphatases often act in tandem to phosphorylate and
dephosphorylate proteins. The protein kinase A signaling pathway
plays important roles in a variety of physiological functions, such as
cell growth and differentiation, ion channel conductivity, synaptic
release of neurotransmitters, and gene transcription (Turnham &
Scott, 2016). In this study, the following seven proteins involved in
Ca2+ signal transduction (nos. 183–189) were upregulated in Z. lati
folia mitochondria during storage: Phosphoinositide phospholipase
C, calcium‐binding EF‐hand family protein, receptor‐like protein
kinase1‐like,MAP3K‐likeprotein,serine/threonine‐proteinkinase,
probableproteinphosphatase2C41,andC2domain‐containingpro
tein‐like.Also,threeproteinkinaseA‐relatedproteins(nos.190–192)
weredownregulatedduringstorage.SmallGTP‐bindingproteins(G
proteins)existineukaryotesfromyeasttohumansandconstitutea
superfamily consisting of more than 100 proteins. This superfamily
is structurally classified into the Ras, Rho, Rab, Sar1/Arf, and Ran
families (Takai, Sasaki, & Matozaki, 20 01). Adenyly l cyclase‐asso‐
ciated protein, which is regulated by G proteins (stimulated by Gs
andinhibitedby Gi),catalyzestheconversionof ATPto3′,5′‐cyclic
adenosinemonophosphate(cAMP)andpyrophosphate.cAMPthen
servesasaregulatorysignalviaspecificcAMP‐bindingtranscription
factors,enzymes(e.g.,cAMP‐dependentkinases),andiontransport
ers (Valsecchi, Konrad, & Manfredi, 2014). In this study, all three of
these DEPs were downregulated during storage. Thus, the Ca2+ and
MAPKsignalingpathwaysmayplayimportantroles in postharvest
senescence of Z. latifolia.
Regarding the other DEPs, three proteins (nos. 194–196) were
related to cofactor binding, one (no. 193) to inositol phosphate
metabolism, one (no. 197) to mitochondrial fission, and one (no.
198)to protein–proteininteractions. Amongthese, harpinbind
ing protein 1 was significantly (p < .05) upregulated, whereas the
otherDEPsweredownregulatedduringstorage.1‐MCPandETH
treatments inhibited and promoted changes in the abundances of
theseDEPsandthusaffected senescence.However,theprecise
roles of these DEPs in posthar vest senescence of Z. latifolia are
unclear.
In addition, 13 DEPs (nos. 199–211) were neither annotated nor
associated with a KEGG pathway, of which 11 were upregulated and
two downregulated during storage at room temperature. Compared
with the co ntrol, 1‐MCP treatment in hibited the stora ge‐induced
changes in themajority of theseproteins,whereasETH treatment
promoted the expression of some, indicating that these proteins are
related to postharvest senescence of Z. latifolia.
18 of 20 
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   LUO et aL.
5 | CONCLUSIONS
In summary, a proteomics analysis of Z. latifolia mitochondria treated
withorwithout1‐MCPandETHduringstorageatroomtemperature
was conducted using iTRAQ.A total of 1,390 proteinswith two or
more peptides were identified, of which 211 showed a significant
(p< .05) change (atleasttwofold)in relativeabundance.The iTRAQ
results were confirmed by PRM. The DEPs were found to be involved
in various cellular and metabolic processes, including respiratory me
tabolism, energy metabolism, ROS metabolism, Ca2+andMAPKsignal
transduction, programed cell death, and degradation of cell structure,
indicating that these processes are closely related to postharvest se
nescence of Z. latifolia. Functional analysis of the DEPs suggested that
the mechanisms underlying postharvest senescence of Z. latifolia are
(a) enhanced activity of the PPP, (b) imbalances in protein, amino acid,
organic acid, and fatty acid metabolism, (c) disrupted energy homeo
stasis,(d)aggravatedoxidativedamage,(e)RNAdegradation,(f)activa‐
tion of the Ca2+,MAPK,andJAsignalingpathways,(g)programedcell
death, (h) excessive biosynthesis of secondary metabolites, and (i) deg
radationofcellstructure.1‐MCPsignificantlyinhibited the changes
in these processes, which retarded the postharvest senescence of Z.
latifolia;incontrast,ETHexertedtheoppositeeffects.Takentogether,
these results enhance our understanding of the molecular mechanisms
of postharvest senescence of Z. latifolia.However,furtherdetailedin‐
vestigation of the roles of these proteins and their functional correla
tions with postharvest senescence of Z. latifolia is needed.
ACKNOWLEDGMENTS
ThisworkwassupportedbytheNationalNaturalScienceFoundation
of China (31401612), the resea rch start‐up fundi ng from Nanjing
Normal University (184080H202B117),and theKeyResearch and
DevelopmentProgramofYunnanProvince(YNVP‐3).
CONFLICTS OF INTEREST
The authors declare that they have no conflicts of interest .
ORCID
Haibo Luo https://orcid.org/0000‐0001‐5978‐707X
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SUPPORTING INFORMATION
Additional supporting information may be found online in the
Suppor ting Information section at the end of the article.
How to cite this article:LuoH,ZhouT,KongX,etal.iTRAQ
based mitochondrial proteome analysis of the molecular
mechanisms underlying postharvest senescence of Zizania
latifolia. J Food Biochem. 2019;e13053. ht t p s : //d o i .
org /10.1111/jfbc.13053
... These objectives have been most effectively realized by regulation of the rate of respiratory metabolism [8], which changes throughout the life of the commodity. Luo et al. [9] found that the respiratory metabolic pathways of post-harvest fruits and vegetables vary during storage. Metabolic activity is especially high during the initial growth of the commodity, ripening of climacteric fruit, and periods of wound healing. ...
... After an initial surge to repair the wounds encountered during harvest, respiration typically declines in vegetative tissues and non-climacteric fruit ( Figure 2) [8]. Plant senescence is affected by respiratory metabolism, which provides the energy for a range of biochemical processes [9]. In leafy crops such as salads, pre-harvest and post-harvest stresses (even of short duration) contribute to changes in metabolism that accelerate quality losses [10]. ...
... In leafy crops such as salads, pre-harvest and post-harvest stresses (even of short duration) contribute to changes in metabolism that accelerate quality losses [10]. The major symptoms of post-harvest senescence of Zizania latifolia are shell etiolation, surface browning, transpiration, respiratory disorders, and tissue hollowness [9]. ...
... Currently,~200,000 metabolites have been found in plants (Wink, 1988). Some scientists have studied Jiaobai through metabolo-and other omic approaches (Luo et al., 2012;Luo et al., 2019;Bata Gouda et al., 2022). Jiaobai is of substantial economic value; however, its shelf-life and quality during post-harvest storage are reduced due to respiratory disorders, shell etiolation, surface browning, transpiration, and tissue hollowness (Luo et al., 2012(Luo et al., , 2019. ...
... Some scientists have studied Jiaobai through metabolo-and other omic approaches (Luo et al., 2012;Luo et al., 2019;Bata Gouda et al., 2022). Jiaobai is of substantial economic value; however, its shelf-life and quality during post-harvest storage are reduced due to respiratory disorders, shell etiolation, surface browning, transpiration, and tissue hollowness (Luo et al., 2012(Luo et al., , 2019. Therefore, researchers believe that the physiological, biochemical, and molecular processes involved in the post-harvest aging of Jiaobai, as well as post-harvest treatment methods to ameliorate aging and improve storage quality, are worth investigating (Bata Gouda et al., 2022;Qian et al., 2023). ...
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Wild rice (Zizania spp.), an aquatic grass belonging to the subfamily Gramineae, has a high economic value. Zizania provides food (such as grains and vegetables), a habitat for wild animals, and paper-making pulps, possesses certain medicinal values, and helps control water eutrophication. Zizania is an ideal resource for expanding and enriching a rice breeding gene bank to naturally preserve valuable characteristics lost during domestication. With the Z. latifolia and Z. palustris genomes completely sequenced, fundamental achievements have been made toward understanding the origin and domestication, as well as the genetic basis of important agronomic traits of this genus, substantially accelerating the domestication of this wild plant. The present review summarizes the research results on the edible history, economic value, domestication, breeding, omics research, and important genes of Z. latifolia and Z. palustris over the past decades. These findings broaden the collective understanding of Zizania domestication and breeding, furthering human domestication, improvement, and long-term sustainability of wild plant cultivation.
... In our study, 1-MCP treatment significantly retarded the weight loss and maintained the visual appearance as well as preserved the color of Z. latifolia by keeping lower a, b and ∆E values as well as delaying the formation of hollow bran. These results are consistent with the findings of Luo et al. [31]. ...
... Previous studies have found that ethylene promotes lignification of fruit and vegetables, while ethylene inhibitor 1-MCP delays lignification by regulating hormones such as ethylene and ABA, and secondary cell wall components, including lignin and cellulose from the substrate, key enzymes, monomer transport and oxidative polymerization (Luo et al., 2019;Zhu et al., 2019;Song et al., 2020;Xie et al., 2020aXie et al., , 2020bXie et al., , 2020cXie et al., , 2020d, but its transcriptional regulation mechanism remains unclear. ...
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Cross-protection is a phenomenon in which infection with a mild virus strain protects host plants against subsequent infection with a closely related severe virus strain. This study showed that a mild strain mutant virus, Tobacco mosaic virus (TMV)-43A could cross protect Nicotiana benthamiana plants against wild-type TMV. Furthermore, we investigated the host responses at the proteome level to identify important host proteins involved in cross-protection. We used the isobaric tags for relative and absolute quantification (iTRAQ) technique to analyze the proteome profiles of TMV, TMV-43A and cross-protected plants at different time-points. Our results showed that TMV-43A can cross-protect N. benthamiana plants from TMV. In cross-protected plants, photosynthetic activities were augmented, as supported by the increased accumulation of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) and geranylgeranyl diphosphate synthase (GGPS) enzymes, which are crucial for chlorophyll biosynthesis. The increased abundance of ROS scavenging enzymes like thioredoxins and L-ascorbate peroxidase would prevent oxidative damage in cross-protected plants. Interestingly, the abundance of defence-related proteins (14–3-3 and NbSGT1) decreased, along with a reduction in virus accumulation during cross-protection. In conclusion, we have identified several important host proteins that are crucial in cross-protection to counter TMV infection in N. benthamiana plants.
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In order to explore the possible mechanism of postharvest senescence in Zizania latifolia, the effects of 10 µL/L 1-methyleyelopropene(1-MCP) and 1.25 mg/L ethylene(ET) treatments on the respiratory metabolism and cell structure associated with senescence in Z. latifolia stored at 25 ℃ for 6 days were investigated. The results showed that the 1-MCP treatment significantly inhibit ed the increase of L, a*, b* value and weight loss of Z. latifolia, whilethe respiratory intensity and reducing sugar content were significantly lower than those in the control. The superoxide dismutase (SOD) activity in samples treated with 1-MCP was significantly induced after 1 day storage but reduced its activity during the remainder storage period. 1-MCP treatment also promoted the cytochrome c oxidase (CCO) activity, while inhibited succinatedehydrogenase (SDH) and peroxidase(POD) activities compared with the control, which resulted in a relatively low relative leakage rate and malondialdehyde(MDA) content. After 6 days storage at 25 ℃, the integrity of cell structure was still maintained. Compared with 1-MCP treatment, ET treatment had the opposite effects on respiratory and reactive oxygen species (ROS) metabolism. These results suggested that 1-MCP treatment could significantly inhibited the respiratory metabolism and ROS production, maintained the energy metabolism balance and cell structural integrity, and then retard the postharvest senescence of Z. latifolia. © 2017, Editorial Board of Modern Food Science and Technology. All right reserved.
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Saline-alkaline stress is one of the primary abiotic stresses that limits crop yields worldwide. The early seedling stage of plants is the most vulnerable stage to stress conditions. In this study, the physiological and phenotypic changes induced by alkali treatments (Na2CO3 and NaHCO3 mixtures) were analyzed for alfalfa (Medicago sativa L. cv. Zhongmu-3) and barrel medic (Medicago truncatula line R108) seedlings. As expected, Zhongmu-3, which is alkali tolerant, and R108, which is alkali sensitive, responded differently to alkaline stress. To characterize the protein expression profiles of these two Medicago species in response to alkaline stress, an iTRAQ-based quantitative proteomic analysis was applied to detect alkali-responsive proteins. A total of 467 differentially changed alkali-responsive proteins were identified from Zhongmu-3 and R108. Compared with their levels in untreated control seedlings, the abundance of 349 proteins increased and 38 proteins decreased in alkali-treated Zhongmu-3 seedlings, whereas 142 proteins increased and 35 proteins decreased in R108 seedlings. Zhongmu-3 and R108 shared 97 common differentially changed proteins, but a large percentage of them showed different change patterns between Zhongmu-3 and R108. Subsequent functional annotation indicated these proteins influenced diverse processes, such as catalytic activity, signaling, and antioxidant activity. The transcript levels of genes encoding 10 differentially changed proteins were determined by quantitative PCR. The data provide new insights into the regulatory mechanisms responsible for alkali stress responses in leguminous plants and have potential implications for breeding of alkaline-resistant alfalfa and other crops.
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The aim of the study was to evaluate in which way nine cultivars of sweet cherry fruit cope with postharvest, artificial inoculation with Monilinia laxa pathogenic fungus through changes in sugars, organic acids and polyphenolic compounds, as well as which phenolics compounds are crucial participants in coping with the disease. Contents of sugars in this study were (g kg⁻¹ dry weight): glucose 205–439 and 268–443, fructose 175–398.9 and 208.6–365.8 and sucrose 20–47.6 and 19.2–38.6 in healthy and infected fruit, respectively. Organic acids detected in sweet cherry cultivars were citric, malic, quinic, shikimic and fumaric acid and their content varied depending on cultivar and treatment. Only ‘Burlat’ accumulated tartaric acid after the infection. Of all phenolic acids, which content decreased in infected fruit, it is clear that only the more tolerant genotypes ‘Merchant’, ‘Lionska’, and ‘Sue’ enhanced content of 3-feruloylquinic acid (in healthy up to 93 and in infected fruit 105.3–139.1 mg kg⁻¹). The most abundant anthocyanins were cyanidin derivatives (80–266.1 and 10–3700 mg kg⁻¹ in healthy and infected fruit, respectively). ‘Burlat’, ‘Junska rana’, Merchant’ and ‘Summit’ dominantly had cyanidin-glucoside, while only infected fruit of ‘Priusadebnaja’ and ‘Asenova rana’ accumulated cyanidin-glucoside. ‘Priusadebnaja’, ‘Asenova rana’ and ‘Lionska’ had cyanidin-rutinoside. ‘Lionska’, ‘Sue’ and ‘Asenova rana’ had higher cyanidin and peonidin derivative contents in infected fruit (1.2 to 3-fold higher). Peonidine derivatives (peonidin glucoside and rutinoside), 5-carboxypyrano-cyanidin-rutinoside content mostly decreased after the infection (14.9–97.7 %). Bearing in mind obtained results, 3-feruloylquinic acid, flavonols and anthocyanins could be proposed as crucial participants in coping with the disease.
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It has been shown that 15 μW·cm⁻² UV-B radiation has the most pronounced effects on γ-aminobutiric acid (GABA), inositol 1,4,5-trisphosphate (IP3) and abscisic acid (ABA) accumulation in 4-day-old soybean sprouts. Nevertheless, its mechanism of action, from the perspective of protein expression, remains largely unknown. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) were employed to investigate UV-B treatment-induced proteomic changes in soybean sprouts. Results showed that UV-B treatment effectively regulated proteins involved in GABA biosynthesis, such as glutamate synthase, glutamate decarboxylase (GAD), methionine synthetase, 5-methyltetrahydropteroyltriglutamate–homocysteine methyltransferase, aminoaldehyde dehydrogenase (AMADH) and inositol phosphate metabolism pathways, including phosphoinositide phospholipase C (PI-PLC), purple acid phosphatase (PAP) and inositol polyphosphate 5-phosphatase. In addition, proteins involved in ABA biosynthesis and signal transduction, such as 9-cis-epoxycarotenoid dioxygenase (NCED), abscisic-aldehyde oxidase (AO), SNF1-related protein kinase (SnRK), protein phosphatase 2C (PP2C), guanine nucleotide-binding protein and calreticulin-3, were also modulated under UV-B treatment.
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Fruit senescence is induced by ethylene in pear, but it is unclear which ethylene responsive factor(s) is involved in. In this study, the ripening fruits of cv. Housui were respectively treated by ethephon and 1-MCP, and the treated fruits were used for transcriptome sequencing to reveal the genes associated with ethylene-induced senescence. As expected, ethylene biosynthesis and signal pathway genes were detected and had remarkably higher levels of expression in all the pre-decayed fruits than in the ripening fruits, but only one novel ERF gene (Pbr022708.1) was induced by ethylene in post-harvested fruits during storage. Moreover, based on the changes of fruit firmness, two ethylene-induced genes that individually encode polygalacturonase (Pbr010853.1) and xyloglucan endotransglucosylase/hydrolase (Pbr040203.1) were isolated to be associated with fruit softening during post-harvest storage. In addition, auxin signal and stress tolerance were likely involved into fruit senescence. These result will be available for understanding gene regulation of post-harvested fruits during storage.