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Changes in the phenotypes of watermelon seedlings under suboptimal temperature acclimation, chilling stress and subsequent recovery
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The temperature drop of plants from the optimal requirements can increase tolerance to severe chilling stress. Photosynthesis and osmoregulators were analyzed during chilling stress to explore the adaptation mechanisms that underlie the induction of chilling tolerance in response to suboptimal temperature. The relationships of these processes to su...
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Context 1
... compared suboptimal temperature-acclimated or nonacclimated watermelon plants during chilling stress and subsequent recovery to determine whether suboptimal temperature acclimation can induce chilling tolerance in watermelons ( Fig. 1 ). The watermelon plants in the control group grew well during 10 days of treatment and maintained relatively stable and low levels of electrolyte leakage and MDA content. ...
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... increased electrolyte leakage (127.2%) and MDA content (35.0%) were observed after 7 days of chilling stress compared with the control ( Fig. 2 ). However, suboptimal temperature acclimation reduced the levels of electrolyte leakage and lipid peroxidation and effectively alleviated injury symptoms under chilling stress in watermelon seedlings ( Fig. 1 ). After 1 day of recovery, non-acclimated watermelon plants were nearly dead, while suboptimal temperature-acclimated watermelon plants grew normally ( Fig. 1 ). ...
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... suboptimal temperature acclimation reduced the levels of electrolyte leakage and lipid peroxidation and effectively alleviated injury symptoms under chilling stress in watermelon seedlings ( Fig. 1 ). After 1 day of recovery, non-acclimated watermelon plants were nearly dead, while suboptimal temperature-acclimated watermelon plants grew normally ( Fig. 1 ). The results showed that suboptimal temperature acclimation can reduce oxidative damage and enhance cell membrane stability to induce the chilling tolerance of watermelon. ...
Citations
... In more detail, the functions of the soluble protein and carbohydrate levels on the improvement in freezing tolerance were validated in sauvignon [43], while the functions of increased proline and carbohydrates under cold stress were also verified in alfalfa [44]. Furthermore, the enhanced chilling tolerance in watermelon achieved via suboptimal temperature acclimation was contributed to by improved photosynthetic adaptability and osmoregulation ability from substances such as proline, soluble sugar and sucrose [45]. From the conclusions above, we determined that the functions of osmoregulation substances and antioxidases were critical to stress; however, in this study, we found that as seeding dates were delayed, osmoregulation substances consistent with antioxidases decreased, which might contribute to the weakening of the environmental adaptability. ...
Rapeseed seeding dates are largely delayed under the rice–rape rotation system, but how rapeseeds adapt to the delayed environment remains unclear. Here, five seeding dates (20 October, 30 October, 10 November, 20 November and 30 November, T1 to T5) were set and the dynamic differences between two late-seeding-tolerant (LST) and two late-seeding-sensitive (LSS) rapeseed cultivars were investigated in a field experiment. The growth was significantly repressed and the foldchange (LST/LSS) of yield increased from 1.50-T1 to 2.64-T5 with the delay in seeding. Both LST cultivars showed higher plant coverage than the LSS cultivars according to visible/hyperspectral imaging and the vegetation index acquired from an unmanned aerial vehicle. Fluorescence imaging, DAB and NBT staining showed that the LSS cultivars suffered more stress damage than the LST cultivars. Antioxidant enzymes (SOD, POD, CAT, APX) and osmoregulation substances (proline, soluble sugar, soluble protein) were decreased with the delay in seeding, while the LST cultivar levels were higher than those of the LSS cultivars. A comparative analysis of transcriptomes and metabolomes showed that 55 pathways involving 123 differentially expressed genes (DEGs) and 107 differentially accumulated metabolites (DAMs) participated in late seeding tolerance regulation, while 39 pathways involving 60 DEGs and 68 DAMs were related to sensitivity. Levanbiose, α-isopropylmalate, s-ribosyl-L-homocysteine, lauroyl-CoA and argino-succinate were differentially accumulated in both cultivars, while genes including isocitrate dehydrogenase, pyruvate kinase, phosphoenolpyruvate carboxykinase and newgene_7532 were also largely regulated. This study revealed the dynamic regulation mechanisms of rapeseeds on late seeding conditions, which showed considerable potential for the genetic improvement of rapeseed.
... Low temperature influences plant growth, development, yield [13], and geographical distribution [14]. Frost and extreme low temperature in winter limit the sustainable growth of trees. ...
CCR4-associated factor I (CAF1) is a deadenylase that plays a critical role in the initial step of mRNA degradation in most eukaryotic cells, and in plant growth and development. Knowledge of CAF1 proteins in woody plants remains limited. Wintersweet (Chimonanthus praecox) is a highly ornamental woody plant. In this study, CpCAF1 was isolated from wintersweet. CpCAF1 belongs to the DEDDh (Asp-Glu-Asp-Asp-His) subfamily of the DEDD (Asp-Glu-Asp-Asp) nuclease family. The amino acid sequence showed highest similarity to the homologous gene of Arabidopsis thaliana. In transgenic Arabidopsis overexpressing CpCAF1, the timing of bolting, formation of the first rosette, and other growth stages were earlier than those of the wild-type plants. Root, lateral branch, rosette leaf, and silique growth were positively correlated with CpCAF1 expression. FLOWERING LOCUS T (FT) and SUPPRESSOROF OVEREXPRESSION OF CO 1 (SOC1) gene expression was higher while EARLY FLOWERING3 (ELF3) and FLOWERING LOCUS C (FLC) gene expression of transgenic Arabidopsis was lower than the wild type grown for 4 weeks. Plant growth and flowering occurrences were earlier in transgenic Arabidopsis overexpressing CpCAF1 than in the wild-type plants. The abundance of the CpCAF1 transcript grew steadily, and significantly exceeded the initial level under 4 °C in wintersweet after initially decreasing. After low-temperature exposure, transgenic Arabidopsis had higher proline content and stronger superoxide dismutase activity than the wild type, and the malondialdehyde level in transgenic Arabidopsis was decreased significantly by 12 h and then increased in low temperature, whereas it was directly increased in the wild type. A higher potassium ion flux in the root was detected in transgenic plants than in the wild type with potassium deficiency. The CpCAF1 promoter was a constitutive promoter that contained multiple cis-acting regulatory elements. The DRE, LTR, and MYB elements, which play important roles in response to low temperature, were identified in the CpCAF1 promoter. These findings indicate that CpCAF1 is involved in flowering and low-temperature tolerance in wintersweet, and provide a basis for future genetic and breeding research on wintersweet.
... Cucurbitaceae is the fourth largest economic plant family in the world and comprises 115 genera containing nearly 1 000 species (Schaefer et al., 2009). Most of these plants are annual or perennial herbaceous or woody vines and are widely distributed in tropical and subtropical regions Lu et al., 2020). Cucurbitaceae plants are known for their important 1 The authors contributed equally to the work. ...
Cucurbitaceae is one of the most important plant families distributed worldwide. Transcription factors (TFs) regulate plant growth at the transcription level. Here, we performed a systematic analysis of 42 641 TFs from 63 families in 14 Cucurbitaceae and 10 non-cucurbit species. Whole-genome duplication (WGD) was the dominant event type in almost all Cucurbitaceae plants. The TF families were divided into 1 210 orthogroups (OGs), of which, 112 were unique to Cucurbitaceae. Although the loss of several gene families was detected in Cucurbitaceae, the gene families expanded in five species that experienced a WGD event comparing with grape. Our findings revealed that the recent WGD events that had occurred in Cucurbitaceae played important roles in the expansion of most TF families. The functional enrichment analysis of the genes that significantly expanded or contracted uncovered five gene families, AUX/IAA, NAC, NBS, HB, and NF-YB. Finally, we conducted a comprehensive analysis of the TCP gene family and identified 16 tendril-related (TEN) genes in 11 Cucurbitaceae species. Interestingly, the characteristic sequence changed from CNNFYFP to CNNFYLP in the TEN gene (Bhi06M000087) of Benincasa hispida. Furthermore, we identified a new characteristic sequence, YNN, which could be used for TEN gene exploitation in Cucurbitaceae. In conclusion, this study will serve as a reference for studying the relationship between gene family evolution and genome duplication. Moreover, it will provide rich genetic resources for functional Cucurbitaceae studies in the future.
... Cold stress resulting from chilling (0~10 o C) and freezing (<0 o C) temperatures significantly impairs the membrane integrity and inhibits photosynthesis, which eventually affects plant growth and development even under optimal light conditio ns (Xie et al., 2018;Gao et al., 2019;Lu et al., 2020). Being sessile organisms, plants have evolved sophisticated but efficient biochemical and physiological mechanisms to cope with cold stress (Chinnusamy et al., 2007). ...
Due to the high sensitivity to cold, the yield and quality of tomato (Solanum lycopersicum L.) are severely restricted by cold stress. The NAC transcription factor (TF) family has been characterized as an important player in plant growth, development, and stress response, but the role of NAC TFs in cold stress and their interaction with other post‐transcriptional regulators such as microRNAs in cold tolerance remain elusive. Here, we demonstrated that SlNAM3, the predicted target of Sl‐miR164a/b‐5p, improved cold tolerance as evidenced by a higher maximum quantum efficiency of photosystem II (Fv/Fm), lower relative electrolyte leakage (REL) and less wilting in SlNAM3‐overexpression plants than wild‐type. Further genetic and molecular confirmation revealed that Sl‐miR164a/b‐5p functioned upstream of SlNAM3 by inhibiting the expression of the latter, thus playing a negative role in cold tolerance. Interestingly, this role is partially mediated by an ethylene‐dependent pathway, as either Sl‐miR164a/b‐5p silencing or SlNAM3 overexpression improved cold tolerance in the transgenic lines by promoting ethylene production. Moreover, silencing the ethylene synthesis genes, SlACS1A, SlACS1B, SlACO1, and SlACO4, resulted in a significant decrease in cold tolerance. Further experiments demonstrated that NAM3 activates SlACS1A, SlACS1B, SlACO1, and SlACO4 transcription by directly binding to their promoters. Taken together, our study identified the miR164a‐NAM3 module conferring cold tolerance in tomato plants via the direct regulation of SlACS1A, SlACS1B, SlACO1, and SlACO4 expression to induce ethylene synthesis.
... Moderate stresses such as high or low temperature, shortage or excess of water, stresses related to the intensity and quality of light perceived during cultivation, trigger plants to react by initiating immediate protection against the stressor (Sabehat et al., 1998;Neta-Sharir, 2005). Exposing plants to sub-optimal growth temperatures between 10 and 20 • C during 7-10 days induced chilling tolerance in tomato plants ( Barrero-Gil et al., 2016); watermelon (Lu et al., 2020); and sweet pepper (Ferguson et al., 1999). Acquired chilling tolerance in plants exposed to low growth temperature is contributed to expression of Crepeat-binding factors (CBF) genes (Singh et al., 2011). ...
... This might indicate that the cold tolerance of "Tarzan" from low temperature cultivation is, at least partly, based on increased membrane integrity. Increased cold tolerance in terms of ability to restore development after prior exposure to low temperature (4 • C) was also found in tomato plants ( Barrero-Gil et al., 2016), watermelon (Lu et al., 2020), and sweet pepper (Ferguson et al., 1999) when cultivated at lower temperatures. There could also be a genetic component. ...
Effect of cultivation temperature during the phase of flowering and fruit development on tomato quality was investigated. Plants of two dwarf tomato cultivars “Ponchi Re” and “Tarzan,” were subjected to three different growth temperatures: 16, 22, or 28°C, starting at the flowering phase. Mature green fruit was harvested and subjected to shelf life at 20°C for 20 days or first stored at 4°C for 15 days, and then placed under shelf life conditions. Fruit quality was determined through red color development, soluble solid content (SSC), softening, weight loss, and cold tolerance. Higher cultivation temperature increased development and production of fruit. Deviation from the 22°C growth temperature led to increased soluble solid content in both cultivars, and smaller fruit diameter in “Tarzan.” Fruit grown at lower temperature had delayed color development during shelf life, and this was further delayed by prior cold storage. “Tarzan” showed more chilling injury (CI) symptoms than “Ponchi Re.” In our experiment, SSC can be manipulated by modulating cultivation temperature, but that it is not associated with CI tolerance. Delayed color formation at the lowest growth temperature observed in “Ponchi Re” tomatoes could be resulted in lower lycopene levels leads to lower ROS scavenging capacity. For “Tarzan” tomatoes, higher firmness at harvest, less softening, and lower weight loss during cold storage in fruit from the lowest cultivation temperature might positively correlated with increased membrane integrity, resulting in increased CI tolerance. This indicates that CI incidence depends on growth temperature and is cultivar dependent in dwarf tomato fruit.
... The possible reason is that P. australis as the dominant species of coastal wetlands in China, having a strong ability in resisting environmental stress by dissipating excess excitation energy, which cannot be used in PSII photochemistry reaction as harmless heat through the xanthophyll cycle (Demmig-Adams et al., 1996;Lu et al., 2020;Zhang et al., 2015). ...
Background
As a fundamental metabolism, leaf photosynthesis not only provides necessary energy for plant survival and growth but also plays an important role in global carbon fixation. However, photosynthesis is highly susceptible to environmental stresses and can be significantly influenced by future climate change.
Methods
In this study, we examined the photosynthetic responses of Phragmites australis ( P . australis ) to three precipitation treatments (control, decreased 30%, and increased 30%) under two thermal regimes (ambient temperature and +4 °C) in environment-controlled chambers.
Results
Our results showed that the net CO 2 assimilation rate ( P n ), maximal rate of Rubisco ( V cmax ), maximal rate of ribulose-bisphosphate (RuBP) regeneration ( J max ) and chlorophyll (Chl) content were enhanced under increased precipitation condition, but were declined drastically under the condition of water deficit. The increased precipitation had no significant effect on malondialdehyde (MDA) content ( p > 0.05), but water deficit drastically enhanced the MDA content by 10.1%. Meanwhile, a high temperature inhibited the positive effects of increased precipitation, aggravated the adverse effects of drought. The combination of high temperature and water deficit had more detrimental effect on P . australis than a single factor. Moreover, non-stomatal limitation caused by precipitation change played a major role in determining carbon assimilation rate. Under ambient temperature, Chl content had close relationship with P n (R ² = 0.86, p < 0.01). Under high temperature, P n was ralated to MDA content (R ² = 0.81, p < 0.01). High temperature disrupted the balance between V cmax and J max (the ratio of J max to V cmax decreased from 1.88 to 1.12) which resulted in a negative effect on the photosynthesis of P . australis . Furthermore, by the analysis of Chl fluorescence, we found that the xanthophyll cycle-mediated thermal dissipation played a major role in PSII photoprotection, resulting in no significant change on actual PSII quantum yield ( Φ PSII ) under both changing precipitation and high temperature conditions.
Conclusions
Our results highlight the significant role of precipitation change in regulating the photosynthetic performance of P . australis under elevated temperature conditions, which may exacerbate the drought-induced primary productivity reduction of P . australis under future climate scenarios.
... Moderate stress, such as temperature, water status or light during cultivation, trigger plants to react by initiating immediate protection against the stressor. As a result to the initial stressor, the plant will develop a certain defence mechanism to confer protection against other stresses simultaneously or subsequently [23][24][25]. For example, water deficit induces production of abscisic acid (ABA) and increases antioxidant levels for superoxide dismutase, CAT, ascorbate peroxidase, and glutathione reductase [26][27][28]. ...
Tomato is a chilling-sensitive fruit. The aim of this study is to examine the role of preharvest blue LED lighting (BL) to induce cold tolerance in ‘Foundation’ tomatoes. Blue and red supplemental LED light was applied to achieve either 0, 12 or 24% additional BL (0B, 12B and 24B). Mature green (MG) or red (R) tomatoes were harvested and cold stored at 4 °C for 0, 5, 10, 15 and 20 d, and then stored for 20 d at 20 °C (shelf life). Chilling injury (CI) indices, color and firmness, hydrogen peroxide, malondialdehyde, ascorbic acid and catalase activity were characterized. At harvest, R tomatoes cultivated at 12B were firmer and showed less coloration compared to fruit of other treatments. These fruits also showed higher loss of red color during cold storage and lower CI symptoms during shelf-life. MG tomatoes cultivated at 12B showed delayed coloring (non-chilled) and decreased weight loss (long cold stored) during shelf life compared to fruit in the other treatments. No effects of light treatments, both for MG and R tomatoes, were observed for the selected antioxidant capacity indicators. Improved cold tolerance for R tomatoes cultivated at 12B points to lycopene having higher scavenging activity at lower concentrations to mitigate chilling injury.
... Both grafted and non-grafted seedlings have been used for watermelon cultivation; however, the use of grafted seedlings has been increasing because of their high yield (Lee et al., 2010). Several studies related to the effects of abiotic stress in watermelon have been performed (Yetişir and Uygur, 2009;Hou et al., 2016;Yanyan et al., 2018;Lu et al., 2020Lu et al., , 2021. However, the effects of salinity, temperature, and drought stresses independently in a single cultivar during a different treatment schedule have not been performed in detail. ...
... Water level injury, which enhances ion imbalance, reduction in antioxidant activity, and low chlorophyll content (Lu et al., 2020;Mlinarić et al., 2021). Chlorophyll content in drought-stressed seedlings was least affected among the three treatment types, although significant changes were observed between control and drought-stressed seedlings during the respective treatment schedule. ...
Chlorophyll fluorescence (CF) is used to measure the physiological status of plants affected by biotic and abiotic stresses. Therefore, we aimed to identify the changes in CF parameters in grafted watermelon seedlings exposed to salt, drought, and high and low temperatures. Grafted watermelon seedlings at the true three-leaf stage were subjected to salinity levels (0, 50, 100, 150, and 200 mM) and temperature [low (8°C), moderate (24°C), and high (40°C)] stresses for 12 days under controlled environmental conditions independently. Eight CF parameters were measured at 2-day intervals using the FluorCam machine quenching protocol of the FluorCam machine. The seedlings were also exposed to drought stress for 3 days independent of salinity and temperature stress; CF parameters were measured at 1-day intervals. In addition, growth parameters, proline, and chlorophyll content were evaluated in all three experiments. The CF parameters were differentially influenced depending on the type and extent of the stress conditions. The results showed a notable effect of salinity levels on CF parameters, predominantly in maximum quantum yield (Fv/Fm), non-photochemical quenching (NPQ), the ratio of the fluorescence decrease (Rfd), and quantum yield of non-regulated energy dissipation in PSII [Y(NO)]. High temperature had significant effects on Rfd and NPQ, whereas low temperature showed significant results in most CF parameters: Fv/Fm, Y(NO), NPQ, Rfd, the efficiency of excitation capture of open photosystem II (PSII) center (Fv′/Fm′), and effective quantum yield of photochemical energy conversion in PSII [Y(PSII)]. Only NPQ and Rfd were significantly influenced by severe drought stress. Approximately, all the growth parameters were significantly influenced by the stress level. Proline content increased with an increase in stress levels in all three experiments, whereas the chlorophyll (a and b) content either decreased or increased depending upon the stressor. The results provided here may be useful for understanding the effect of abiotic stresses on CF parameters and the selection of index CF parameters to detect abiotic stresses in grafted watermelon seedlings.
... Photosynthesis is particularly sensitive to chilling during plant growth and development (Ruelland et al., 2009). Photosynthetic light harvesting is regulated by nonphotochemical quenching (NPQ), which allows the dissipation of harmful excess energy as heat through its energy-dependent NPQ (qE) component to avoid photodamage under chilling stress (Li et al., 2009;Niyogi and Truong, 2013;Ruban, 2016;Lu et al., 2020). In the green alga Chlamydomonas reinhardtii, UVR8 induces the accumulation of specific members of the light-harvesting complex (LHC) superfamily, particularly LHC Stress-Related 1 and Photosystem II Subunit S, which contribute to qE and reduce photodamage to the photosynthesis machinery under UV-B (Allorent et al., 2016). ...
Low-temperature stress is the main limiting factor of cucurbit crop cultivation as it affects crop yield and quality. The identification of genes involved in cold tolerance is a crucial aspect of pumpkin rootstock breeding. Here, we examined the function of a pumpkin Regulator of Chromosome Condensation 1 (CmRCC1) gene in the root development and cold stress responses of tobacco (Nicotiana benthamiana). CmRCC1 expression was differentially induced in pumpkin root, stem, and leaf under cold stress. Transient transformation showed that CmRCC1 is located in the nucleus. CmRCC1 overexpression in tobacco increased the gravitropic set-point angle in lateral roots, as well as root diameter and volume. The expression of auxin polar transport factors, PIN1 and PIN3, decreased and increased in CmRCC1-overexpressed plants, respectively. Yeast two-hybrid verification and luciferase complementation imaging assay showed that CmRCC1 interacts with CmLAZY1. Furthermore, the decreases in maximum quantum yield of PS II, the effective quantum yield of PS II, and electron transfer rate and the increases in quantum yield of nonregulated energy dissipation and malondialdehyde content were compromised in transgenic plants compared with wild-type plants under cold stress. The results suggest that CmRCC1 plays an important role in the regulation of root architecture and positively modulates cold tolerance.
... RCA is an AAA + ATPase that uses the energy from ATP hydrolysis to remove inhibitory sugars at the RCA site to generate a catalytically active enzyme with a temperature optimum below 40 • C [69,70]. In the present study, an RCA unigene (Unigene11360) was highly expressed under CK conditions (FPKM of 653.40), but with grazing, its expression was significantly down-regulated ( Figure 2 and Table S6), indicative of its varying roles under the four grazing conditions. ...
... In the present study, an RCA unigene (Unigene11360) was highly expressed under CK conditions (FPKM of 653.40), but with grazing, its expression was significantly down-regulated ( Figure 2 and Table S6), indicative of its varying roles under the four grazing conditions. Under CK conditions, the abundant RCA can accelerate CO 2 fixation, activate Rubisco and induce the expression of key genes in the CBC [70]. However, the microenvironment of plants survive grazing changes because of a decrease in humidity and increases in temperature, surface exposure, light radiation, and evaporation, which ultimately lead to unstable and inactive RCA [71,72]. ...
Organisms have evolved effective and distinct adaptive strategies to survive. Stipa grandis is a representative species for studying the grazing effect on typical steppe plants in the Inner Mongolia Plateau. Although phenotypic (morphological and physiological) variations in S. grandis in response to long-term grazing have been identified, the molecular mechanisms underlying adaptations and plastic responses remain largely unknown. Here, we performed a transcriptomic analysis to investigate changes in gene expression of S. grandis under four different grazing intensities. As a result, a total of 2357 differentially expressed genes (DEGs) were identified among the tested grazing intensities, suggesting long-term grazing resulted in gene expression plasticity that affected diverse biological processes and metabolic pathways in S. grandis. DEGs were identified in RNA-Seq and qRT-PCR analyses that indicated the modulation of the Calvin–Benson cycle and photorespiration metabolic pathways. The key gene expression profiles encoding various proteins (e.g., ribulose-1,5-bisphosphate carboxylase/oxygenase, fructose-1,6-bisphosphate aldolase, glycolate oxidase, etc.) involved in these pathways suggest that they may synergistically respond to grazing to increase the resilience and stress tolerance of S. grandis. Our findings provide scientific clues for improving grassland use and protection and identifying important questions to address in future transcriptome studies.
