Figure 1 - uploaded by Guodong Wang
Content may be subject to copyright.
Source publication
NAD biosynthesis, including from aspartate via the de novo pathway and from nicotinate (NA) via the Preiss-Handler pathway, is conserved in land plants. Meanwhile, different NA conjugates, which are mainly involved in NA detoxification, have been found in all tested land plants. Among these conjugates, MeNA (NA methyl ester) has been widely detecte...
Contexts in source publication
Context 1
... mononucleotide (NaMN) is converted to NAD via adenylation by nicotinamide mononucleotide adenylyltransferase (NaMNAT), encoded by At5g55810 and amidation by NAD synthase (NADS, encoded by At1g55090). The last two enzymes in this pathway also participate in the NAD salvage pathway ( Hashida et al., 2007) (Figure 1). The five-step NAD de novo pathway is conserved across the plant kingdom, from unicellular green algae (Chlamydomonas reinhardtii) to flowering plants ( Lin et al., 2010). ...
Context 2
... far, only homozygous knockdown mutants of AO, with an approximately 45% reduction in expression, have been characterized ( Macho et al., 2012). The NAD salvage pathway in land plants, similar to that in most bacteria, starts from NAM, which is sequentially catalyzed by nicotinamidase (NIC1, encoded by At2g22570 in Arabidopsis), nicotinate phosphoribosyltransferase (NaPRT, encoded by At2g23420 and At4g36940 in Arabidopsis), NaMNAT, and NADS ( Figure 1). ...
Context 3
... further identified T-DNA insertion lines for the AO and QS genes (SALK_013920 and SALK_149250, which were designated ao-1 and qs-1, respectively) but were unable to obtain plants that were homozygous for either null allele because these plants could not survive beyond the embryonic stage ( Katoh et al., 2006). In this study, we successfully obtained homozygous ao-1 and qs-1 plants by growing the plants on 1 / 2 MS or soil supplemented with NAM during the entire screening procedure (Supplemental Figure 1). Note that there is 2 mM NA in regular 1 / 2 MS medium (0.5 mg/l vitamin B3 in the standard basal MS medium); therefore, the MS medium used in this study was home-made and free of NA. ...
Context 4
... that changes in the transcript levels of MES1, 4, 7, and 9 will not affect the net changes in MeNA esterase levels in MES2 transgenic plants, as the transcript levels of these genes are much lower (>50-fold) than the transcript level of the MES2 gene (Supplemental Figure 9). Chemical analysis showed that the levels of all the NAD-related compounds except MeNA were not significantly different between Col-0 and the selected transgenic plants ( Figure 7B and Supplemental Figure 10). As expected, the NaMT1-overexpressing plants (18.6 ± 2.0 pmol/g FW for OE3 and 18.1 ± 2.5 pmol/g FW for OE13; n = 3) had 3-fold higher MeNA levels than the WT (5.1 ± 0.37 pmol/g FW; n = 3), while the namt1 mutants (1.1 ± 0.41 pmol/g FW for namt1-1 and 0.86 ± 0.47 pmol/g FW for namt1-2; n = 3) had approximately 5-fold lower MeNA levels than the WT. ...
Context 5
... contrast, MES2-overexpressing plants exhibited higher MeNA uptake (approximately 1.5-to 1.6-fold) than the WT, which probably caused the growth retarda- tion of MES2-overexpressing plants upon treatment with 1.5 mM MeNA. Notably, a clear [ 14 C]MeNA signal was only detected in the leaves of the MES2 knockdown plants (Supplemental Figure 11B). ...
Context 6
... plants, however, only one route for NAM metabolism is currently known, involving the conversion to NA by NIC (Figure 1) (Wagner and Wagner, 1985;Zheng et al., 2004;Hunt et al., 2007;Wang and Pichersky, 2007). We have previously shown that abiotic stress stimulates NAD degradation and NA accumulation ( Wang and Pichersky, 2007;Li et al., 2015). ...
Context 7
... have previously shown that abiotic stress stimulates NAD degradation and NA accumulation ( Wang and Pichersky, 2007;Li et al., 2015). The accumulation of NA under stress conditions suggests that the activity of NaPRT, which converts NA to NaMN, is a limiting factor in the NAD salvage pathway under these conditions (Figure 1). Consistent with this hypothesis, Ashihara et al. (2005) observed that NIC activity was two orders of magnitude higher than NaPRT activity in suspension cells of Picea glauca, and a similar phenomenon has been observed in Escherichia coli, which utilizes the plant-like NAD salvage pathway ( Wubbolts et al., 1990). ...
Context 8
... all four NA conjugates share the physiological function of NA detoxification, the genes responsible for producing these NA conjugates exhibit different tissue specificities in Arabidopsis: AtNAOGT (UGT74F2) and AtNANGT (UGT76C4) are highly expressed in dry seeds; AtNANMT1 is predominantly expressed in inflorescences; and AtNaMT1 is highly expressed in root tissue. Unlike the formation of NANG, NAOG, and Tg, the reversible methylation of NA is transient and does not disturb the free NA and NAD pools in plants (Supplemental Figure 10). The relationship between the NA pool and NAD pool in plants and the physiological functions of each NA conjugate under different growth conditions needs further investigation. ...
Context 9
... the natural property of NAM as a common inhibitor of NAD-consuming enzymes (such as Sir2 and PARPs) also limits its application as a ''NAD-boosting'' chemical for human beings (Bitterman et al., 2002). NR and NaR were also detected in Arabidopsis seedlings (Supplemental Figure 10), and further investigation into whether these NAD precursors could be transported between organs for NAD production in plants is merited. ...
Similar publications
Mannitol is abundant in a wide range of organisms, playing important roles in biotic and abiotic stress responses. Nonetheless, mannitol is not produced by a vast majority of plants, including many important crop plants. Mannitol-producing transgenic plants displayed improved tolerance to salt stresses though mannitol production was rather low, in...
Citations
... whereas the asterisk indicated significant difference tested by one-way ANOVA, ns, no significance; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001. (F) Schematic diagram showing the NAD metabolism and Nicotinate conjugation in Arabidopsis(Wu et al., 2018). (G)The comparison of Differential Accumulation of Metabolites (DAMs) in NAD and NAM metabolism upon SMF treatment, or iron stress, or the combination of SMF treatment and iron stress. ...
Static magnetic field (SMF) plays important roles in various biological processes of many organisms including plants, though the molecular mechanism remains largely unclear. Here in this study, we evaluated different magnetic setups to test their effects on growth and development on Arabidopsis (Arabidopsis thaliana), and discovered that plant growth was significantly enhanced by inhomogeneous SMF generated by a regular triangular prism magnet perpendicular to the direction of gravity. Comparative transcriptomic analysis revealed that auxin synthesis and signal transduction genes were upregulated by SMF exposure. SMF also facilitated plants to maintain the iron homeostasis. The expression of iron metabolism-related genes was downregulated by SMF, however, the iron content in plant tissues remains relatively unchanged. Furthermore, SMF exposure also helped the plants to reduce ROS level and synergistically maintain the oxidant balance by enhanced activity of antioxidant enzymes and accumulation of nicotinamide. Taken together, our data suggested that SMF is involved in regulating the growth and development of Arabidopsis thaliana through maintaining iron homeostasis and balancing oxidative stress, which could be beneficial for plant survival and growth. The work presented here would extend our understanding of the mechanism and the regulatory network of how magnetic field affects the plant growth, which would provide insights into the development of novel plant synthetic biology technologies to engineer stress-resistant and high-yielding crops.
... Trigonelline is a well-described plant metabolite. Its synthesis from NA via methylation confers protective and adaptive functions 4,48 , without an established reutilization as a Preiss-Handler substrate 49,50 . Consequently, trigonelline is particularly abundant in plant-derived food products, such as coffee beans and fenugreek seeds, which have been reported to modulate endogenous trigonelline levels in humans 4,51,52 . ...
Mitochondrial dysfunction and low nicotinamide adenine dinucleotide (NAD+) levels are hallmarks of skeletal muscle ageing and sarcopenia1,2,3, but it is unclear whether these defects result from local changes or can be mediated by systemic or dietary cues. Here we report a functional link between circulating levels of the natural alkaloid trigonelline, which is structurally related to nicotinic acid4, NAD+ levels and muscle health in multiple species. In humans, serum trigonelline levels are reduced with sarcopenia and correlate positively with muscle strength and mitochondrial oxidative phosphorylation in skeletal muscle. Using naturally occurring and isotopically labelled trigonelline, we demonstrate that trigonelline incorporates into the NAD+ pool and increases NAD+ levels in Caenorhabditis elegans, mice and primary myotubes from healthy individuals and individuals with sarcopenia. Mechanistically, trigonelline does not activate GPR109A but is metabolized via the nicotinate phosphoribosyltransferase/Preiss–Handler pathway5,6 across models. In C. elegans, trigonelline improves mitochondrial respiration and biogenesis, reduces age-related muscle wasting and increases lifespan and mobility through an NAD+-dependent mechanism requiring sirtuin. Dietary trigonelline supplementation in male mice enhances muscle strength and prevents fatigue during ageing. Collectively, we identify nutritional supplementation of trigonelline as an NAD+-boosting strategy with therapeutic potential for age-associated muscle decline.
... It is suggested that these NA conjugates are also involved in plant growth and response to abiotic stresses. To date, O-and N-conjugates of NA have been well investigated in Arabidopsis (Li et al., 2015;Wu et al., 2018;Liu et al., 2019). The formation of NaOG is catalyzed by AtUGT74F2 at the carboxyl position of NA, while AtUGT76C4/AtUGT76C5 utilizes UDP-glucose, UDPxylose, and UDP-arabinose as sugar donors to produce NaNG, NaNP, and NaNRha (Li et al., 2015;Liu et al., 2019), respectively. ...
Plants serve as rich repositories of diverse chemical compounds collectively referred to as specialized metabolites (SMs). These compounds are of importance for adaptive processes, including interactions with various microbes both beneficial and harmful. Considering microbes as bioreactors, the chemical diversity undergoes dynamic changes when root-derived specialized metabolites (RSMs) and microbes encounter each other in the rhizosphere. Recent advancements in sequencing techniques and molecular biology tools have not only accelerated the elucidation of biosynthetic pathways of RSMs but also unveiled the significance of RSMs in plant-microbe interactions. In this review, we provide a comprehensive description of the effects of RSMs on microbe assembly in the rhizosphere and the influence of corresponding microbial changes on plant health, incorporating the most up-to-date information available. Additionally, we highlight open questions that remain for a deeper understanding of and harnessing the potential of RSM-microbe interactions to enhance plant adaptation to the environment. Finally, we propose a pipeline for investigating the intricate associations between root exometabolites and the rhizomicrobiome.
... In addition to the three first identified SAMT, BAMT, and TCS methyltransferases, other functional members of the SABATH family have gradually been identified in different species. In A. thaliana, jasmonic acid carboxyl methyltransferase (JMT) [12] , paraxanthine methyltransferase (PXMT) [13] , indoe-acetic acid carboxyl methyltransferase (IAMT) [14] , farnesoic acid carboxyl methyltransferase (FAMT) [15] , gibberellic acid carboxy methyltransferase (GAMT) [16] , benzoic/salicylic acid carboxyl methyltransferase (BSMT) [17] , nicotinate methyltransferase (NAMT) [18] and carlactonoic acid methyltransferase (CLAMT) [19] were identified. SA, JA, IAA, and other phytohormones are converted into methyl esters under different environmental conditions through the catalysis of methyltransferases, which improve plant resistance and participate in various plant developmental processes such as seed germination, flower and fruit development, leaf senescence and abscission by regulating the content of endogenous hormones in plants [20−23] . ...
Plant SABATH methyltransferases are a class of enzymes that catalyze the transfer of the methyl group from S-adenosyl-L-methionine (SAM) to the carboxyl group or the nitrogen group of the substrate to form small molecule methyl esters or N-methylated compounds, which are involved in various secondary metabolite biosynthesis and have important impacts on plant growth, development, and defense reactions. We previously reported the monoterpenoid indole alkaloids (MIAs) cadambine biosynthetic pathway in Neolamarckia cadamba, a woody tree species that provides an important traditional medicine widely used to treat diseases such as diabetes, leprosy, and cancer in Southeast Asia. However, the functions of NcSABATHs in cadambine biosynthesis remain unclear. In this study, 23 NcSABATHs were identified and found to be distributed on 12 of the total 22 chromosomes. Gene structure, conserved motifs, and phylogenetic analysis showed that NcSABATHs could be divided into three groups. According to cis-element analysis, the NcSABATH promoters contained a large number of elements involved in light, plant hormone, and environmental stress responses, as well as binding sites for the BBR-BPC, DOF, and MYB transcription factor families. Based on RNA-seq data and qRT-PCR analysis, the NcSABATH genes exhibited diverse tissue expression patterns. Furthermore, NcSABATH7/22, which clustered with LAMT in the same clade, were both up-regulated under MeJA treatment. The correlation analysis between gene expression and cadambine content showed that NcSABATH7 potentially participated in cadambine biosynthesis. Taken together, our study not only enhanced our understanding of SABATH in N. cadamba but also identified potential candidate genes involved in cadambine biosynthesis.
... The identified metabolites which could contribute to algal growth promotion includes: 1) thiamine and vitamin B 6 , which are essential micronutrients for plant health, stress alleviation and disease resistance (Fitzpatrick and Chapman, 2020;Mangel et al., 2019); 2) riboflavin, which has increased production of lipids and pigments in Chlorella sorokiniana (Lopez et al., 2019); 3) nicotinate and nicotinamide (a complex of vitamin B 3 ). Their phosphorylated derivates participate in energy metabolism and biomass synthesis in plants (Wu et al., 2018); 4) biotin, which at low concentrations can increase germination ; and 5) lipoic acid and porphyrin, which induce the photosystem II and gene expressions of carbon fixation and chlorophyll related enzymes (Jin et al., 2021;Sezgin et al., 2019). However, pantothenate, folate, retinol, and ubiquinone are not directly correlated with the growth of phytoplankton or plants. ...
Haematococcus lacustris is a chlamydomonadalean with high biotechnological interest owing to its capacity to produce astaxanthin, a valuable secondary carotenoid with extraordinary antioxidation properties. However, its prolonged growth has limited its utility commercially. Thus, rapid growth to attain high densities of H. lacustris cells optimally producing astaxanthin is an essential biotechnological target to facilitate profitable commercialisation. Our study focused on characterising the bacterial communities associated with the alga's phycosphere by metagenomics. Subsequently, we altered the bacterial consortia in combined co-culture with key beneficial bacteria to optimise the growth of H. lacustris. The algal biomass increased by up to 2.1-fold in co-cultures, leading to a 1.6-fold increase in the astaxanthin yield. This study attempted to significantly improve the H. lacustris growth rate and biomass yield via Next-Generation Sequencing analysis and phycosphere bacterial augmentation, highlighting the possibility to overcome the hurdles associated with astaxanthin production by H. lacustris at a commercial scale.
... Deregulation of AO, QS and QPT levels in Arabidopsis thaliana leaves has shown that such enzymes are critical in the control of pyridine nucleotide levels and its derivatives (Schippers et al., 2008;Macho et al., 2012;Pétriacq et al., 2012Pétriacq et al., , 2016b. Although the physiological role of trigonelline in plants remain unclear, trigonelline can also contribute, to a lesser extent, to the resynthesis of NAD + and undergoes longdistance transport in Arabidopsis (Upmeier et al., 1988;Wu et al., 2018). ...
... Central metabolism (21%) remained noticeable due to the presence of enzymes involved in lipid-, amino acid-metabolisms, pentose phosphate pathway and protein degradation (9, 4, 4 and 4%, respectively) Likewise, Arabidopsis NICs were also reported to influence NAD + contents (Hunt et al., 2007;Wang and Pichersky, 2007). Metabolism of nicotinate has also received recent attention in various plant species (Matsui et al., 2007;Li et al., 2015;Wu et al., 2018). However, nicotinate conjugates are particularly difficult to measure via MS-based metabolomics due to unreliable ionisations of such compounds in the mass spectrometer, as it is the case for NAD + and nicotinamide (Guérard et al., 2011). ...
... Likewise, Arabidopsis NICs were also reported to influence NAD + contents (Hunt et al., 2007;Wang and Pichersky, 2007). Metabolism of nicotinate has also received recent attention in various plant species (Matsui et al., 2007;Li et al., 2015;Wu et al., 2018). In this context, we observed increased expression of NMT and NaMe esterase genes in the developing fruit (Figure 3), suggesting that Na metabolism is important to sustain NAD(P) homeostasis. ...
The change of paradigm in redox biology, considering ROS as finely-tuned signals modulating plant metabolism, shed new light on redox networks, especially in plants where multiple sources of ROS are possible and associated with many “ROS processing systems” (Noctor et al., 2018), while major redox buffers (e.g. ASC, GSH and NAD) clearly appear at the forefront of oxidative regulations. ROS production and redox signals arising from are crucial to harmonious metabolism and participate in adaptive signalling pathways throughout development and in response to the environment. In parallel, the development of mathematical integrative modelling permitted by new approaches providing quantitative description through metabolic fluxes.Progress in understanding the molecular signatures involved in the redox regulations controlling the trade-off between fruit development and stress pathways will help to define novel strategies for optimal fruit production and storage (Beauvoit et al., 2018). However, knowledge on redox biology in fruit is sparsely documented, although principles originating from leaves tissues are valuable while waiting for comprehensive studies that provide more extensive knowledge on fruits.In this regard, my PhD project aims to provide the first quantitative description of core redox metabolism in a developmental context while developing and implementing protocols allowing the rapid quantification of major redox compounds. In addition, the use of an integrative modelling approach will allow deciphering the implication of redox flux in the control of redox balance during fruit development.For this purpose:1.A multiscale omics study focusing on NAD metabolism during tomato fruit development provides a better view of the implication of NAD metabolism in redox and central metabolism,2.Major redox buffers and total antioxidant capacity are assessed using targeted biochemical analyses of the ascorbate-glutathione cycle, while untargeted LC-MS analysis provides a global comparison of developmental stages, in particular for secondary redox compounds. Furthermore, mutant plants enriched in ascorbate have been analysed to study the impact of an increase in ASC on tomato fruit,3.The data sets obtained are finally used to develop a kinetic-based model of the ASC-GSH cycle, allowing the investigation of redox fluxes and their regulation during tomato fruit development.Besides, I participate in developing a redox platform to implement at the Bordeaux Metabolome Facility, allowing me to participate in some other projects, such as the characterisation of new NAD kinase (Dell’Aglio et al., 2019) and the characterisation of ASC-enriched mutants (Deslous et al., 2021). I also had the opportunity to participate in the writing of reviews aiming to bring together the scattered knowledge available on redox metabolism in fruits and in response to extreme environments (Decros et al., 2019 ; Dussarrat et al., 2021). Furthermore, the preliminary data obtained allowed the designing of new projects more focused on the involvement of redox metabolism during the fruit setting phase. To this end, different ASC mutant fruits have been analysed at several flower and young fruit stages.
... Some studies have shown that NAD plays an important role in the response of plants to environmental signals. The dynamic balance of NAD and NADH is essential for plants to cope with abiotic stress (Hashida et al., 2010;Wu et al., 2018). ...
Drought stress is a serious abiotic stress source that affects the growth and fruit quality of peach trees. However, the molecular mechanism of the NUDIX hydrolase family in peaches in response to drought stress is still unclear. Here, we isolated and identified the PpNUDX8 (Prupe.5G062300.1) gene from the peach NUDIX hydrolase family, and found that PpNUDX8 has a typical NUDIX hydrolase domain. In this study, we performed 15% PEG6000 drought treatment on peach seedlings, and qRT–PCR analysis showed that 15% PEG6000 induced the transcription level of PpNUDX8. Overexpression of PpNUDX8 reduced the tolerance of calli to 4% PEG6000 treatment. Compared with wild-type apple calli, PpNUDX8 transgenic apple calli had a lower fresh weight and higher MDA content. After 15% PEG6000 drought treatment, PpNUDX8 transgenic tobacco had a greater degree of wilting and shorter primary roots than Under control conditions. The chlorophyll, soluble protein, and proline contents in the transgenic tobacco decreased, and the MDA content and relative conductivity increased. At the same time, PpNUDX8 negatively regulated ABA signal transduction and reduced the transcriptional expression of stress response genes. In addition, PpNUDX8 was not sensitive to ABA, overexpression of PpNUDX8 reduced the expression of the ABA synthesis-related gene NCED6 and increases the expression of the ABA decomposition-related gene CYP1 in tobacco, which in turn leads to a decrease in the ABA content in tobacco. In addition, Under control conditions, overexpression of PpNUDX8 destroyed the homeostasis of NAD and reduced nicotinamide adenine dinucleotide (NADH) in tobacco. After 15% PEG6000 drought treatment, the changes in NAD and NADH in PpNUDX8 transgenic tobacco were more severe than those in WT tobacco. In addition, PpNUDX8 also interacted with PpSnRk1γ (Prupe.6G323700.1).
... Methylation is a particularly common enzymatically catalyzed substitution in the biosynthetic pathways of these varied metabolites and often involves enzymes of the salicylic acid/benzoic acid/theobromine (SABATH) methyltransferase (MT) family . Numerous SABATH enzymes have been functionally characterized including those that methylate a wide array of carboxylic acids (Ross et al. 1999;Kolosova et al. 2001;Seo et al. 2001;Yang et al. 2006;Kapteyn et al. 2007;Varbanova et al. 2007;Murata et al. 2008;Hippauf et al. 2010;Petronikolou et al. 2018;Wu et al. 2018) as well as thiols and ring nitrogen atoms (Kato et al. 1996;Uefuji et al. 2003;McCarthy and McCarthy 2007;Zhao et al. 2012;Huang et al. 2016). The enzyme family appears particularly diverse in angiosperms with approximately 25-40 members in Arabidopsis and Oryza, whereas mosses and liverworts appear to have only approximately four to nine enzymes encoded in their genomes Zhao et al. 2008Zhao et al. , 2012Zhang et al. 2019). ...
Next-generation sequencing has resulted in an explosion of available data, much of which remains unstudied in terms of biochemical function; yet, experimental characterization of these sequences has the potential to provide unprecedented insight into the evolution of enzyme activity. One way to make inroads into the experimental study of the voluminous data available is to engage students by integrating teaching and research in a college classroom such that eventually hundreds or thousands of enzymes may be characterized. In this study, we capitalize on this potential to focus on SABATH methyltransferase enzymes that have been shown to methylate the important plant hormone, salicylic acid (SA), to form methyl salicylate. We analyze data from 76 enzymes of flowering plant species in 23 orders and 41 families to investigate how widely conserved substrate preference is for salicylic acid methyltransferase (SAMT) orthologs. We find a high degree of conservation of substrate preference for SA over the structurally similar metabolite, benzoic acid, with recent switches that appear to be associated with gene duplication and at least three cases of functional compensation by paralogous enzymes. The presence of Met in active site position 150 is a useful predictor of SA methylation preference in SABATH methyltransferases but enzymes with other residues in the homologous position show the same substrate preference. Although our dense and systematic sampling of SABATH enzymes across angiosperms has revealed novel insights, this is merely the "tip of the iceberg" since thousands of sequences remain uncharacterized in this enzyme family alone.
... NAD(P)(H) participates in almost every cellular metabolic pathway. The level of NAD(P)(H) needs continuous maintenance in order to avoid cell death due to the lack of NAD (Wu et al. 2018). Previously, it has been shown that NAD level is maintained during the vegetative growth stage, even if NADS, which encodes the enzyme converting NaAD to NAD in the NAD salvage pathway (Fig. 1a), is overexpressed (Hashida et al. 2016). ...
... NA generated in the roots is reversibly methylated to a detoxified form, methyl nicotinate (MeNA), and transported to shoots for NAD biosynthesis under abiotic stresses (Wu et al. 2018). Interestingly, WT roots accumulate 22.6 and 28.6 times more NA in the roots as compared to the shoots under drought stress and control conditions respectively, highlighting the importance of tissue specific accumulation of NA particularly under drought stress conditions (Fig. S5a). ...
Key message
Overexpressing Nicotinamidase 3 gene, and the exogenous application of its metabolite nicotinic acid (NA), enhance drought stress tolerance and increase biomass in Arabidopsis thaliana.
Abstract
With progressive global climatic changes, plant productivity is threatened severely by drought stress. Deciphering the molecular mechanisms regarding genes responsible for balancing plant growth and stress amelioration could imply multiple possibilities for future sustainable goals. Nicotinamide adenine dinucleotide (NAD) biosynthesis and recycling/ distribution is a crucial feature for plant growth. The current study focuses on the functional characterization of nicotinamidase 3 (NIC3) gene, which is involved in the biochemical conversion of nicotinamide (NAM) to nicotinic acid (NA) in the salvage pathway of NAD biosynthesis. Our data show that overexpression of NIC3 gene enhances drought stress tolerance and increases plant growth. NIC3-OX plants accumulated more NA as compared to WT plants. Moreover, the upregulation of several genes related to plant growth/stress tolerance indicates that regulating the NAD salvage pathway could significantly enhance plant growth and drought stress tolerance. The exogenous application of nicotinic acid (NA) showed a similar phenotype as the effect of overexpressing NIC3 gene. In short, we contemplated the role of NIC3 gene and NA application in drought stress tolerance and plant growth. Our results would be helpful in engineering plants with enhanced drought stress tolerance and increased growth potential.
... NaMT1 fine-tuned the long-distance transportation of MeNA and was finally used in NAD production. The abiotic stress treatments (salt, abscisic acid and mannitol) that increase the degradation of NAD can induce the expression of NAMT1 [40]. Gene2572, the Arabidopsis thaliana homolog is KCS1, encodes the ketoacyl-CoA synthase of 3-ketoacyl-CoA, is involved in the synthesis of long-chain fatty acids in vegetative growth tissues and plays a role in wax biosynthesis [41]. ...
CO2 application is one of the important ways to promote crop growth and increase yield, especially for facility crop cultivation. Since carrot is a widespread vegetable, the area of off-season facility cultivation has been increasing in recent years. Jasmonic acid (JA) is a signal molecule that responds quickly to external stimulation in plants, so it is very important to study the JA metabolism under CO2 enrichment. In this study, the JA content and the biomass were measured during the growth and development of carrots under natural conditions and CO2 enrichment in greenhouse. The results showed that the JA content in carrot leaves under CO2 enrichment was higher than that of the control at all stages except harvest stage, but the leaf biomass and root yield were increased at all stages. RNA sequencing identified 482 differentially expressed genes (DEGs). By analyzing the JA synthesis pathway, five DEGs were obtained. In addition, GO annotation found 21 genes that respond to JA or are related to JA-mediated signal transduction. Among them, seven genes are directly related to growth and development, five genes are related to hormonal regulation, and six genes are related to stress. This study showed that JA was highly responsive to CO2 enrichment: JA not only regulated carrot growth, but also responded to abiotic stress. This research provides new insights into the process of plants adapting to high levels of CO2.
