Stress Tolerance In Cotton Research Articles

Effect of Combined Application of Wood Vinegar Solution and Biochar on Saline Soil Properties and Cotton Stress Tolerance.

Biomass pyrolysis by-products, such as biochar (BC) and wood vinegar (WV), are widely used as soil conditioners and efficiency enhancers in agriculture. A pot experiment was conducted to examine the effects of WV, both alone and in combination with BC, on soil properties in mildly saline soil and on cotton stress tolerance. The results demonstrated that BC and WV application, either individually or together, increased soil nutrient content. The combined application was more effective than the individual applications, resulting in a 5.18-20.12% increase in organic matter, a 2.65-15.04% increase in hydrolysable nitrogen, a 2.23-58.05% increase in effective phosphorus, and a 2.71-29.38% increase in quick-acting potassium. Additionally, the combined application of WV and BC led to greater improvements in cotton plant height, net photosynthetic rate (Pn), leaf nitrate reductase (NR), superoxide dismutase (SOD), and catalase (CAT) activities compared to the application of BC or WV alone. The enhancements in this study varied across different parameters. Plant height showed an increase of 14.32-21.90%. Net photosynthetic rate improved by 13.56-17.60%. Leaf nitrate reductase increased by 5.47-37.79%. Superoxide dismutase and catalase showed improvements of 5.82-64.95% and 10.36-71.40%, respectively (p < 0.05). Moreover, the combined treatment outperformed the individual applications of WV and BC, resulting in a significant decrease in MDA levels by 2.47-51.72% over the experimental period. This combined treatment ultimately enhanced cotton stress tolerance. Using the entropy weight method to analyze the results, it was concluded that the combined application of WV and BC could enhance soil properties in mildly saline soils, increase cotton resistance, and hold significant potential for widespread application.

A novel role of the cotton calcium sensor CBL3 was involved in Verticillium wilt resistance in cotton.

Verticillium wilt, causes mainly by the soilborne pathogen Verticillium dahliae, is a devastated vascular disease resulting in huge financial losses in cotton, so research on improving V. dahliae stress tolerance in cotton is the utmost importance. Calcium as the second messenger acts as a crucial role in plant innate immunity. Cytosolic Ca2+during the pathogen infection is a significant increase in plant immune responses. Calcineurin B-like (CBL) proteins are widely known calcium sensors that regulate abiotic stress responses. However, the role of cotton CBLs in response to V. dahliae stress remains unclear. To discover and utilize the gene to Verticillium wilt resistance and defense response mechanism of cotton. Through screening the gene to Verticillium wilt resistance in cotton, four GhCBL3 copies were obtained from the current common cotton genome sequences. The protein domain and phylogenetic analyses of GhCBL3 were performed using NCBI Blast, DNAMAN, and MotifScan programs. Real-time RT-PCR was used to detect the expression of GhCBL3 gene in cotton seedlings under various stress treatments. The expression construct including GhCBL3 cDNA was transduced into Agrobacterium tumefaciens (GV3101) by heat shock method and transformed into cotton plants by Virus-Induced Gene Silencing (VIGS) method. The results of silencing of GhCBl3 on ROS accumulation and plant disease resistance in cotton plants were assessed. A member of calcineurin B-like proteins (defined as GhCBL3) in cotton was obtained. The expression of GhCBL3 was significantly induced and raised by various stressors, including dahliae, jasmonic acid (JA) and H2O2 stresses. Knockdown GhCBL3 in cotton by Virus-Induced Gene Silencing analysis enhanced Verticillium wilt tolerance and changed the occurrence of reactive oxygen species. Some disease-resistant genes were increased in GhCBL3-silencing cotton lines. GhCBL3 may function on regulating the Verticillium dahliae stress response of plants.

Improved physiological responses and stress tolerance in cotton against Fusarium wilt with Trichoderma harzianum treatment

Cotton is a vital cash crop in the agricultural economy. Many abiotic stresses and pathogenic diseases reduce cotton yield, with cotton wilt being a major threat caused by Fusarium oxysporum f.sp. vasinfectum (FOV). In the present study, the antagonistic potential of Trichoderma harzianum, along with its extracted volatile and non-volatile compounds, was evaluated against FOV. In a dual culture assay, T. harzianum showed 71.4% inhibition of FOV. The volatile compounds extracted from T. harzianum showed 54.9% inhibition of FOV, while the non-volatile compounds reduced the growth of F. oxysporum f.sp. vasinfectum by 64.21%. The evaluation of vegetative traits of cotton plants indicated increased biomass when treated with T. harzianum. The activity of antioxidant defense enzymes Catalase activity (CAT), Superoxide dismutase activity (SOD), and Peroxidase activity (POX) was highest in cotton plants treated with both T. harzianum and F. oxysporum f.sp. vasinfectum, indicating an activation of the plant defense mechanisms in response to these treatments. Protein content, Malondialdehyde Content (MDA), proline content, electrolyte leakage, and H2O2 content, which are stress markers, were at their maximum under F. oxysporum f.sp. vasinfectum stress. Physiological features, including stomatal conductance, photosynthesis rate, Soil Plant Analysis Development (SPAD) chlorophyll value, and relative water content, were highest in plants treated with T. harzianum, as T. harzianum improves and boosts plant growth. Hence, T. harzianum is an effective biological control agent against FOV.

Zinc Oxide Nanoparticles and Zinc Sulfate Alleviate Boron Toxicity in Cotton (Gossypium hirsutum L.).

Boron toxicity significantly hinders the growth and development of cotton plants, therefore affecting the yield and quality of this important cash crop worldwide. Limited studies have explored the efficacy of ZnSO4 (zinc sulfate) and ZnO nanoparticles (NPs) in alleviating boron toxicity. Nanoparticles have emerged as a novel strategy to reduce abiotic stress directly. The precise mechanism underlying the alleviation of boron toxicity by ZnO NPs in cotton remains unclear. In this study, ZnO NPs demonstrated superior potential for alleviating boron toxicity compared to ZnSO4 in hydroponically cultivated cotton seedlings. Under boron stress, plants supplemented with ZnO NPs exhibited significant increases in total fresh weight (75.97%), root fresh weight (39.64%), and leaf fresh weight (69.91%). ZnO NPs positively affected photosynthetic parameters and SPAD values. ZnO NPs substantially reduced H2O2 (hydrogen peroxide) by 27.87% and 32.26%, MDA (malondialdehyde) by 27.01% and 34.26%, and O2- (superoxide anion) by 41.64% and 48.70% after 24 and 72 h, respectively. The application of ZnO NPs increased the antioxidant activities of SOD (superoxide dismutase) by 82.09% and 76.52%, CAT (catalase) by 16.79% and 16.33%, and POD (peroxidase) by 23.77% and 21.66% after 24 and 72 h, respectively. ZnO NP and ZnSO4 application demonstrated remarkable efficiency in improving plant biomass, mineral nutrient content, and reducing boron levels in cotton seedlings under boron toxicity. A transcriptome analysis and corresponding verification revealed a significant up-regulation of genes encoding antioxidant enzymes, photosynthesis pathway, and ABC transporter genes with the application of ZnO NPs. These findings provide valuable insights for the mechanism of boron stress tolerance in cotton and provide a theoretical basis for applying ZnO NPs and ZnSO4 to reduce boron toxicity in cotton production.

Effect of carboxymethyl cellulose and gibberellic acid-enriched biochar on osmotic stress tolerance in cotton

The deleterious impact of osmotic stress, induced by water deficit in arid and semi-arid regions, poses a formidable challenge to cotton production. To protect cotton farming in dry areas, it’s crucial to create strong plans to increase soil water and reduce stress on plants. The carboxymethyl cellulose (CMC), gibberellic acid (GA3) and biochar (BC) are individually found effective in mitigating osmotic stress. However, combine effect of CMC and GA3 with biochar on drought mitigation is still not studied in depth. The present study was carried out using a combination of GA3 and CMC with BC as amendments on cotton plants subjected to osmotic stress levels of 70 (70 OS) and 40 (40 OS). There were five treatment groups, namely: control (0% CMC-BC and 0% GA3-BC), 0.4%CMC-BC, 0.4%GA3-BC, 0.8%CMC-BC, and 0.8%GA3-BC. Each treatment was replicated five times with a completely randomized design (CRD). The results revealed that 0.8 GA3-BC led to increase in cotton shoot fresh weight (99.95%), shoot dry weight (95.70%), root fresh weight (73.13%), and root dry weight (95.74%) compared to the control group under osmotic stress. There was a significant enhancement in cotton chlorophyll a (23.77%), chlorophyll b (70.44%), and total chlorophyll (35.44%), the photosynthetic rate (90.77%), transpiration rate (174.44%), and internal CO2 concentration (57.99%) compared to the control group under the 40 OS stress. Thus 0.8GA3-BC can be potential amendment for reducing osmotic stress in cotton cultivation, enhancing agricultural resilience and productivity.

Functional characterization of GhNAC2 promoter conferring hormone- and stress-induced expression: a potential tool to improve growth and stress tolerance in cotton.

The online version contains supplementary material available at 10.1007/s12298-024-01411-2.

Identification and in silico functional characterization of a Ghnac29-like transcription factor in response to abiotic stress tolerance in cotton

Abiotic stresses produce an adverse impact on plant growth and crop productivity. In most developing countries including Pakistan, economies are agriculture-based and are affected badly by extreme weather changes. These climate changes influence the development and yield of the cotton crop. Numerous stress-tolerant genes including transcription factor genes have been known over the past few years that can serve as a key to regulating the stress-associated gene expression in cotton. The NAC transcription factor, which has a significant function in plant production, growth, and reaction to different environmental stresses, is now one of the major groups of plant TFs. In the current study GhNAC29-like gene, an uncharacterized cotton-born member of the NAC gene family, was functionally characterized. To amplify the full-length sequence of GhNAC29-like gene, total RNA was isolated followed by cDNA synthesis. The GhNAC29-like sequence was characterized by in-silico analysis including similarity search, multiple sequence alignment and phylogenetic analysis. The result indicates that GhNAC29-like shows maximum similarity with GrNAC29-like which is 91 %. In-silico analysis through different software also shows that GhNAC29-like is a membrane-soluble protein that is found within the nucleus and membrane of the cell, having no signal peptide located on it. This protein contains no transmembrane helix and it doesn't go under post-translational modifications. Further analysis shows that the conserved domain (pfamNAM) is present in the GhNAC29-like protein structure and it has NAM (No apical meristem) superfamily. The expression analysis of the stress-related NAC29-like gene Gossypium hirsutum was also studied using the CottonFGD database. GhNAC29-like gene expression is maximum under cold stress and increases with time whereas, under heat, drought, and salt stress, gene expression increases at a certain level, and then it decreases. High temperatures above 40 completely cause the loss of activity of protein due to which the yield decreases in high-temperature areas of Pakistan. This analysis shows that low temperatures are good for the protein activity (GhNAC29-like) and can make better the yield production rate. Abiotic factors including heat, drought, and excessive salinity are among the major causes of yield loss around the globe. Hence, GhNAC29-like shows a significant increase in expression in various abiotic stresses. Furthermore In-silico promoter analysis has shown the presence of various putative stress reactive cis-regulatory motifs. These findings suggest that cotton GhNAC genes have a function in the transcriptional regulation of environmental stresses to plant response.

Cotton GhNAC4 promotes drought tolerance by regulating secondary cell wall biosynthesis and ribosomal protein homeostasis.

Drought has a severe impact on the quality and yield of cotton. Deciphering the key genes related to drought tolerance is important for understanding the regulation mechanism of drought stress and breeding drought-tolerant cotton cultivars. Several studies have demonstrated that NAC transcription factors are crucial in the regulation of drought stress, however, the related functional mechanisms are still largely unexplored. Here, we identified that NAC transcription factor GhNAC4 positively regulated drought stress tolerance in cotton. The expression of GhNAC4 was significantly induced by abiotic stress and plant hormones. Silencing of GhNAC4 distinctly impaired the resistance to drought stress and overexpressing GhNAC4 in cotton significantly enhanced the stress tolerance. RNA-seq analysis revealed that overexpression of GhNAC4 enriched the expression of genes associated with the biosynthesis of secondary cell walls and ribosomal proteins. We confirmed that GhNAC4 positively activated the expressions of GhNST1, a master regulator reported previously in secondary cell wall formation, and two ribosomal protein-encoding genes GhRPL12 and GhRPL18p, by directly binding to their promoter regions. Overexpression of GhNAC4 promoted the expression of downstream genes associated with the secondary wall biosynthesis, resulting in enhancing secondary wall deposition in the roots, and silencing of GhRPL12 and GhRPL18p significantly impaired the resistance to drought stress. Taken together, our study reveals a novel pathway mediated by GhNAC4 that promotes secondary cell wall biosynthesis to strengthen secondary wall development and regulates the expression of ribosomal protein-encoding genes to maintain translation stability, which ultimately enhances drought tolerance in cotton.

A review of approaches to enhance salt stress tolerance in cotton by genetic engineering

Due to climate change, deserts are expanding, water reservoirs are drying, soil erosion is becoming more serious, and salinity areas are expanding worldwide. Among these disasters, soil salinization is one of the serious issues that affect agricultural production, with significant effects on plant development. Although plants have a solid adaptation to severe environmental conditions, their vulnerability to some abiotic stresses is still preserved in the plant genome. Cotton is a salt stress-tolerant crop among other main cash crops. However, its tolerance is limited in overwatered soil conditions or water-deficient soil. Several research investigations have been carried out to date to better understand salinity stress responses in various cotton species. The accumulation of salt due to irrigation-dependent practices exerts an adverse impact on crop productivity. However, this deleterious effect can be mitigated through a comprehensive understanding of the mechanisms by which certain plants flourish under saline conditions. Over the past few decades, there has been a notable augmentation in mechanistic comprehension, leading to the initiation of discovery-oriented methodologies aimed at discerning the genetic determinants of salt tolerance. Recent studies are showing the results of the manipulation of some important genes and proteins for salt tolerance using modern approaches. The identification of salt-resistance genes from salt-tolerant germplasm resources plays an essential role in improving the yield of cotton in saline soils. In this paper, we reviewed what has been achieved in cotton in terms of the development of its salt tolerance using genetic engineering.

Genome-wide identification of R-SNARE gene family in upland cotton and function analysis of GhVAMP72l response to drought stress.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (R-SNAREs) mainly promoted the assembly of the SNARE complex to drive the final membrane fusion step of membrane transport. Previous research on R-SNAREs has mainly focused on development and growth and has rarely been involved in abiotic stress, especially in cotton. Here, we performed a comprehensive analysis of R-SNARE genes in upland cotton. In total, 51 Gh-R-SNARE genes across six phylogenetic groups were unevenly distributed on 21 chromosomes. Cis elements related to plant growth and response to abiotic stress responses were found in the promoter region of Gh-R-SNAREs. Nine Gh-R-SNARE genes were obviously upregulated under drought stress conditions by RNA-seq and qRT-PCR analysis. Among them, GhVAMP72l might be the key candidate gene contributing to drought stress tolerance in cotton by virus-induced gene silencing (VIGS) assay. These results provide valuable insights for the functional analysis of cotton R-SNAREs in response to drought stress and highlight potential beneficial genes for genetic improvement and breeding in cotton.

Transcriptome Analysis Revealed that GhPP2C43-A Negatively Regulates Salinity Tolerance in an Introgression Line from a Semi-Wild Upland Cotton.

Salt damage is a major threat to sustainable cotton production owing to the limited arable land in China, which is mainly occupied by the production of staple food crops. Salt-stress-tolerant cotton varieties are lacking in production, and the mechanisms underpinning salt stress tolerance in cotton remain enigmatic. Here, DM37, an intraspecific introgression line from Gossypium hirsutum race yucatanense acc TX-1046 into the G. hirsutum acc TM-1 background, was found to be highly tolerant to salt stress. Its seed germination rate and germination potential were significantly higher than those of the recipient TM-1 under salt stress. Physiological analysis showed that DM37 had a higher proline content and peroxidase activity and lower Na+/K+ ratios at the seedling stage, which is consistent with a higher seedling survival rate after durable salt stress. Furthermore, comparative transcriptome analysis revealed that responsive patterns to salt stress in DM37 were different from those in TM-1. Weighted correlation network analysis demonstrated that co-expression modules associated with salt stress in DM37 also differed from those in TM-1. From this analysis, GhPP2C43-A, a phosphatase gene, was found to exhibit negative regulation of salt stress tolerance verified by virus-induced gene silencing and the genration of transgenic Arabidopsis. Gene expression showed that GhPP2C43-A in TM-1 was induced by durable salt stress but not in DM37, probably attributable to a variation in the cis-element in its promoter, thereby conferring different salt stress tolerance. These results provide new genes/germplasms from semi-wild cotton in salt-stress-tolerant cotton breeding, as well as new insight into the mechanisms underpinning salt stress tolerance in cotton.

Genome-wide identification and functional analysis of ICE genes reveal that Gossypium thurberi “GthICE2” is responsible for cold and drought stress tolerance

Cold stress has been found to have a negative impact on cotton growth and annual production. To address this issue, the utilization of cold-tolerant gene resources from wild species of Gossypium is crucial for genetic improvements in cultivated cotton. ICE (inducer of CBF expression) are the key regulators of cold tolerance in plants, however, there is relatively little information on ICE genes in cotton. Herein, we performed comprehensive bioinformatics analyses of the ICE gene family in eight cotton species. Phylogenetic analysis showed that 52 ICE genes were clustered into four subgroups. Cis-regulatory elements analysis suggests that the expression of ICE genes might be regulated by light, plant hormones, and various environment stresses. Higher expression of GthICE2 was observed in leaves as compared to roots and stems, in response to cold, drought, and exogenous hormone ABA. Furthermore, overexpression of GthICE2 in A. thaliana led to higher germination and survival rates, longer root length, lower ion leakage, and induction under cold and drought stress. Histochemical staining showed that oxidative damage in transgenic lines was much lower compared to wild-type plants. Lower MDA contents and higher SOD and POD activities were observed in overexpressed plants. Y1H and LUC assays revealed that GthICE2 might activate the expression of GthCBF4, a cold-responsive gene, by connecting with the MYC cis-element present in the promoter of GthCBF4. GthICE2 confers cold and drought stress tolerance in cotton. Our findings add significantly to the existing knowledge regarding cold stress tolerance and helps to elucidate cold response mechanisms in cotton.

GhMYB44 enhances stomatal closure to confer drought stress tolerance in cotton and Arabidopsis

MYB genes play crucial roles in plant response to abiotic stress. However, the function of MYB genes in cotton during abiotic stress is less well elucidated. Here, we found an R2R3-type MYB gene, GhMYB44, was induced by simulated drought (PEG6000) and ABA in three cotton varieties. After drought stress, the GhMYB44-silenced plants showed substantial changes at the physiological level, including significantly increased malondialdehyde content and decreased SOD activity. Silencing the GhMYB44 gene increased stomatal aperture and water loss rate, reduced plant drought tolerance. Transgenic Arabidopsis thaliana over-expressed GhMYB44 (GhMYB44-OE) enhanced resistance to mannitol-simulated osmotic stress. The stomatal aperture of the GhMYB44-OE Arabidopsis was significantly smaller than those of the wild type (WT), and the GhMYB44-OE Arabidopsis increased tolerance to drought stress. Transgenic Arabidopsis had higher germination rate under ABA treatment compared to WT, and the transcript levels of AtABI1, AtPP2CA and AtHAB1 were suppressed in GhMYB44-OE plants, indicating a potential role of GhMYB44 in the ABA signal pathway. These results showed that GhMYB44 acts as a positive regulator in plant response to drought stress, potentially useful for engineering drought-tolerant cotton.

Priming with sodium nitroprusside and hydrogen peroxide increases cotton seed tolerance to salinity and water deficit during seed germination and seedling development

A major difficulty in cotton crops is high-quality seed production, which interferes with plant vigor and establishment. Techniques such as seed physiological conditioning have been reported due to their ability to improve stress tolerance in seeds and plants. Considering this, we carried out this research to evaluate the use of signaling molecules to increase cotton plant stress tolerance. Seeds were conditioned on aerated solutions of indoleacetic acid (100 µM), hydrogen peroxide (100 µM), chitosan (0.75 mM), melatonin (0.2 mM), sodium nitroprusside (100 µM), and pure water (hydropriming), at 20 °C for 24 h. Then seeds were washed with running water and dried in an oven with forced air circulation at 25 °C for 24 h. Treated seeds or nontreated seeds were placed to germinate under salinity (10 dS m−1 NaCl) and water deficit by using polyethylene glycol (PEG 6000) at − 0.6 MPa, and with nonstressed condition (water). The solutions mentioned were used to moisten the Germitest® paper roll at 2.5 times its weight. We also analyzed the activity of the enzymes superoxide dismutase, catalase, and ascorbate peroxidase, as well as the content of proline, hydrogen peroxide, and lipid peroxidation. Physiological conditioning with signaling molecules effectively improved cotton seed germination under stress, especially to hydrogen peroxide and sodium nitroprusside, which resulted in better performance on the parameters of germination and seedling growth. As stress conditions induced oxidative stress, as observed by lipid peroxidation, we found that physiological conditioning improved the seed antioxidant system, with hydrogen peroxide and sodium nitroprusside resulting in better performance. Our results highlighted the potential of sodium nitroprusside and hydrogen peroxide as inducers of stress tolerance in cotton.

The CCCH-Type Zinc-Finger Protein GhC3H20 Enhances Salt Stress Tolerance in Arabidopsis thaliana and Cotton through ABA Signal Transduction Pathway

The CCCH zinc-finger protein contains a typical C3H-type motif widely existing in plants, and it plays an important role in plant growth, development, and stress responses. In this study, a CCCH zinc-finger gene, GhC3H20, was isolated and thoroughly characterized to regulate salt stress in cotton and Arabidopsis. The expression of GhC3H20 was up-regulated under salt, drought, and ABA treatments. GUS activity was detected in the root, stem, leaves, and flowers of ProGhC3H20::GUS transgenic Arabidopsis. Compared with the control, the GUS activity of ProGhC3H20::GUS transgenic Arabidopsis seedlings under NaCl treatment was stronger. Through the genetic transformation of Arabidopsis, three transgenic lines of 35S-GhC3H20 were obtained. Under NaCl and mannitol treatments, the roots of the transgenic lines were significantly longer than those of the wild-type (WT) Arabidopsis. The leaves of the WT turned yellow and wilted under high-concentration salt treatment at the seedling stage, while the leaves of the transgenic Arabidopsis lines did not. Further investigation showed that compared with the WT, the content of catalase (CAT) in the leaves of the transgenic lines was significantly higher. Therefore, compared with the WT, overexpression of GhC3H20 enhanced the salt stress tolerance of transgenic Arabidopsis. A virus-induced gene silencing (VIGS) experiment showed that compared with the control, the leaves of pYL156-GhC3H20 plants were wilted and dehydrated. The content of chlorophyll in pYL156-GhC3H20 leaves was significantly lower than those of the control. Therefore, silencing of GhC3H20 reduced salt stress tolerance in cotton. Two interacting proteins (GhPP2CA and GhHAB1) of GhC3H20 have been identified through a yeast two-hybrid assay. The expression levels of PP2CA and HAB1 in transgenic Arabidopsis were higher than those in the WT, and pYL156-GhC3H20 had expression levels lower than those in the control. GhPP2CA and GhHAB1 are the key genes involved in the ABA signaling pathway. Taken together, our findings demonstrate that GhC3H20 may interact with GhPP2CA and GhHAB1 to participate in the ABA signaling pathway to enhance salt stress tolerance in cotton.

Genome wide identification of GDSL gene family explores a novel GhirGDSL26 gene enhancing drought stress tolerance in cotton

BackgroundCurrent climate change scenarios are posing greater threats to the growth and development of plants. Thus, significant efforts are required that can mitigate the negative effects of drought on the cotton plant. GDSL esterase/lipases can offer an imperative role in plant development and stress tolerance. However, thesystematic and functional roles of the GDSL gene family, particularly in cotton under water deficit conditions have not yet been explored.ResultsIn this study, 103, 103, 99, 198, 203, 239, 249, and 215 GDSL proteins were identified in eight cotton genomes i.e., Gossypium herbaceum (A1), Gossypium arboretum (A2), Gossypium raimondii (D5), Gossypium hirsutum (AD1), Gossypium barbadense (AD2), Gossypium tomentosum (AD3), Gossypium mustelinum (AD4), Gossypium darwinii (AD5), respectively. A total of 198 GDSL genes of Gossypium hirsutum were divided into eleven clades using phylogenetic analysis, and the number of GhirGDSL varied among different clades. The cis-elements analysis showed that GhirGDSL gene expression was mainly related to light, plant hormones, and variable tense environments. Combining the results of transcriptome and RT-qPCR, GhirGDSL26 (Gh_A01G1774), a highly up-regulated gene, was selected for further elucidating its tole in drought stress tolerance via estimating physiological and biochemical parameters. Heterologous expression of the GhirGDSL26 gene in Arabidopsis thaliana resulted in a higher germination and survival rates, longer root lengths, lower ion leakage and induced stress-responsive genes expression under drought stress. This further highlighted that overexpressed plants had a better drought tolerance as compared to the wildtype plants. Moreover, 3, 3’-diaminobenzidine (DAB) and Trypan staining results indicated reduced oxidative damage, less cell membrane damage, and lower ion leakage in overexpressed plants as compared to wild type. Silencing of GhirGDSL26 in cotton via VIGS resulting in a susceptible phenotype, higher MDA and H2O2 contents, lower SOD activity, and proline content.ConclusionOur results demonstrated that GhirGDSL26 plays a critical role in cotton drought stress tolerance. Current findings enrich our knowledge of GDSL genes in cotton and provide theoretical guidance and excellent gene resources for improving drought tolerance in cotton.

Genome-Wide Analysis of WRKY Gene Family and Negative Regulation of GhWRKY25 and GhWRKY33 Reveal Their Role in Whitefly and Drought Stress Tolerance in Cotton.

The WRKY transcription factor family is marked by its significant responsiveness to both biotic and abiotic plant stresses. In the present study, the WRKY family of Gossypium hirsutum has been identified and classified into three groups based on the number of conserved WRKY domains and the type of zinc finger motif. This classification is further validated by conserved domain and phylogenetic analysis. Two members of the WRKY family, WRKY25 and WRKY33, have been targeted through VIGS in G. hirsutum. VIGS-infiltrated plants were evaluated under drought stress and whitefly infestation. It was observed that GhWRKY33-downregulated plants showed a decrease in whitefly egg and nymph population, and GhWRKY33 was found to be a strong negative regulator of whitefly and drought stress, while GhWRKY25 was found to be a moderate negative regulator of whitefly and drought stress. As the targeted genes are transcription factors influencing the expression of other genes, the relative expression of other stress-responsive genes, namely MPK6, WRKY40, HSP, ERF1, and JAZ1, was also analyzed through qRT-PCR. It was found elevated in GhWRKY33-downregulated plants, while GhWRKY25-downregulated plants through VIGS showed the elevated expression of ERF1 and WRKY40, a slightly increased expression of HSP, and a lower expression level of MPK6. Overall, this study provides an important insight into the WRKY TF family and the role of two WRKY TFs in G. hirsutum under drought stress and whitefly infestation. The findings will help to develop crops resilient to drought and whitefly stress.

GhCDPK60 positively regulates drought stress tolerance in both transgenic Arabidopsis and cotton by regulating proline content and ROS level.

Calcium-Dependent Protein Kinases (CDPKs) involved in regulating downstream components of calcium signaling pathways play a role in tolerance to abiotic stresses and seed development in plants. However, functions of only a few cotton CDPKs have been clarified at present. In this study, 80 conserved CDPKs in Gossypium hirsutum L. were identified and characterized, which was divided into four subgroups. Among them, the transcript level of GhCDPK60 was significantly upregulated under drought and several hormone treatments. And we found that the expression levels of several stress-inducible genes down-regulated in GhCDPK60-silence cotton and up-regulated in GhCDPK60-overexpressing Arabidopsis. In addition, physiological analyses demonstrated that GhCDPK60 improved drought stress tolerance by improving the osmotic adjustment ability and reducing the accumulation of reactive oxygen species (ROS) in plants. These findings broaden our understanding of the biological roles of GhCDPK60 and mechanisms underlying drought stress tolerance in cotton.

Trihelix Transcriptional Factor GhGT26 of Cotton Enhances Salinity Tolerance in Arabidopsis.

Cotton (Gossypium hirsutum L.), the most important textile crop worldwide, often encounters abiotic stress during its growing season and its productivity is significantly limited by adverse factors. Trihelix transcription factors (also known as GT factors) are important proteins involved in the morphological development and responses to abiotic stress in plants. However, their functions and molecular mechanisms in the cotton toward abiotic stress response remain unclear. In this study, a member (GhGT26) of the cotton Trihelix family was functionally characterized in the model plant Arabidopsis. This protein containing a SANT domain belongs to the GT-1 subgroup of trihelix proteins. GhGT26 was widely expressed in tissues (with the highest level in flower) and responded to high salt and ABA treatments at the transcriptional level. Using the Arabidopsis protoplast assay system, we found that the GhGT26 protein was located in the cell nuclei. The EMSA assay revealed that the GhGT26 protein could bind to the Site1-type GT cis elements (GT-3a) and MYB elements MRE3 and MRE4. The overexpression of GhGT26 improved plant tolerance to salt stress in transgenic Arabidopsis plants. Although ABA inhibits root elongation, the statistical analysis revealed that the root lengths of GhGT26-overexpressing Arabidopsis were the same as the wild plants after ABA treatment. Our results demonstrate that GhGT26 positively regulates salt stress via ABA-independent pathways. This evidence suggests that the GhGT26 may participate in the regulation of stress tolerance in cotton.

Overexpression of a cotton nonspecific lipid transfer protein gene, GhLTP4, enhances drought tolerance by remodeling lipid profiles, regulating abscisic acid homeostasis and improving tricarboxylic acid cycle in cotton

Drought is a major abiotic stress that causes severely crop yield loss worldwide. Lipid transfer proteins (LTPs) play an essential role during plant growth and cell signaling transduction associated with stress responses. However, the regulatory circuits involved in drought stress remain largely unresolved. Here, we reported that a nonspecific lipid transfer protein, namely GhLTP4 , positively modulated drought stress tolerance in cotton. GhLTP4 (synonym Pfs6 , GenBank: ABO42261) was preferentially expressed in fiber cells, while, it was also strongly induced by phytohormone abscisic acid (ABA) and drought stress treatments. Compared with wild type, over- and down-expression of GhLTP4 in cotton led to the increased and decreased drought tolerance, respectively. Overexpression of GhLTP4 remarkably increased lipid components and the accumulation of culticular waxes in transgenic cotton leaves under normal condition. Under drought stress, GhLTP4 -overexpressing transgenic cotton exhibited the remodeled lipid profiles, more ABA contents, and the improved tricarboxylic acid cycle process. Taken together, we reveal the function and underlying mechanisms of GhLTP4 in regulating cotton drought tolerance and create valuable genetic accessions for cotton drought-tolerant breeding. • Overexpression of GhLTP4 enhances significantly cotton drought tolerance. • Overexpression of GhLTP4 alters the lipid profiles of cotton leaf tissue. • Overexpression of GhLTP4 improves the drought tolerance by remodeling lipid profiles and ABA homeostasis. • Overexpression of GhLTP4 promotes tricarboxylic acid metabolism under drought stress.