Brassinosteroids regulate cotton fiber elongation by modulating very-long-chain fatty acid biosynthesis.

Brassinosteroid (BR), a growth-promoting phytohormone, regulates many plant growth processes including cell development. However, the mechanism by which BR regulates fiber growth is poorly understood. Cotton (Gossypium hirsutum) fibers are an ideal single-cell model in which to study cell elongation due to their length. Here we report that BR controls cotton fiber elongation by modulating very-long-chain fatty acid (VLCFA) biosynthesis. BR deficiency reduces the expression of 3-ketoacyl-CoA synthases (GhKCSs), the rate-limiting enzymes involved in VLCFA biosynthesis, leading to lower saturated VLCFA contents in pagoda1 (pag1) mutant fibers. In vitro ovule culture experiments show that BR acts upstream of VLCFAs. Silencing of BRI1-EMS-SUPPRESOR 1.4 (GhBES1.4), encoding a master transcription factor of the BR signaling pathway, significantly reduces fiber length, whereas GhBES1.4 overexpression produces longer fibers. GhBES1.4 regulates endogenous VLCFA contents and directly binds to BR RESPONSE ELEMENTS (BRREs) in the GhKCS10_At promoter region, which in turn regulates GhKCS10_At expression to increase endogenous VLCFA contents. GhKCS10_At overexpression promotes cotton fiber elongation, whereas GhKCS10_At silencing inhibits cotton fiber growth, supporting a positive regulatory role for GhKCS10_At in fiber elongation. Overall, these results uncover a mechanism of fiber elongation through crosstalk between BR and VLCFAs at the single-cell level.

Suppression of plant immunity by Verticillium dahliae effector Vd6317 through AtNAC53 association.

Verticillium dahliae, a soil-borne fungal pathogen, compromises host innate immunity by secreting a plethora of effectors, thereby facilitating host colonization and causing substantial yield and quality losses. The mechanisms underlying the modulation of cotton immunity by V. dahliae effectors are predominantly unexplored. In this study, we identified that the V. dahliae effector Vd6317 inhibits plant cell death triggered by Vd424Y and enhances PVX viral infection in Nicotiana benthamiana. Attenuation of Vd6317 significantly decreased the virulence of V. dahliae, whereas ectopic expression of Vd6317 in Arabidopsis and cotton enhanced susceptibility to V. dahliae infection, underscoring Vd6317's critical role in pathogenicity. We observed that Vd6317 targeted the Arabidopsis immune regulator AtNAC53, thereby impeding its transcriptional activity on the defense-associated gene AtUGT74E2. Arabidopsis nac53 and ugt74e2 mutants exhibited heightened sensitivity to V. dahliae compared to wild-type plants. A mutation at the conserved residue 193L of Vd6317 abrogated its interaction with AtNAC53 and reduced the virulence of V. dahliae, which was partially attributable to a reduction in Vd6317 protein stability. Our findings unveil a hitherto unrecognized regulatory mechanism by which the V. dahliae effector Vd6317 directly inhibits the plant transcription factor AtNAC53 activity to suppress the expression of AtUGT74E2 and plant defense.

Genome-Wide Analysis of Cotton MYB Transcription Factors and the Functional Validation of GhMYB in Response to Drought Stress.

MYB transcription factors play important roles during abiotic stress responses in plants. However, little is known about the accurate systematic analysis of MYB genes in the four cotton species, Gossypium hirsutum, G. barbadense, G. arboreum and G. raimondii. Herein, we performed phylogenetic analysis and showed that cotton MYBs and Arabidopsis MYBs were clustered in the same subfamilies for each species. The identified cotton MYBs were distributed unevenly on chromosomes in various densities for each species, wherein genome-wide tandem and segment duplications were the main driving force of MYB family expansion. Synteny analysis suggested that the abundant collinearity pairs of MYBs were identified between G. hirsutum and the other three species, and that they might have undergone strong purification selection. Characteristics of conserved motifs, along with their consensus sequence, promoter cis elements and gene structure, revealed that MYB proteins might be highly conserved in the same subgroups for each species. Subsequent analysis of differentially expressed genes and expression patterns indicated that most GhMYBs might be involved in response to drought (especially) and salt stress, which was supported by the expression levels of nine GhMYBs using real-time quantitative PCR. Finally, we performed a workflow that combined virus-induced gene silencing and the heterologous transformation of Arabidopsis, which confirmed the positive roles of GhMYBs under drought conditions, as validated by determining the drought-tolerant phenotypes, damage index and/or water loss rate. Collectively, our findings not only expand our understanding of the relationships between evolution and function of MYB genes, but they also provide candidate genes for cotton breeding.

GhRCD1 promotes cotton tolerance to cadmium by regulating the GhbHLH12-GhMYB44-GhHMA1 transcriptional cascade.

Heavy metal pollution poses a significant risk to human health and wreaks havoc on agricultural productivity. Phytoremediation, a plant-based, environmentally benign, and cost-effective method, is employed to remove heavy metals from contaminated soil, particularly in agricultural or heavy metal-sensitive lands. However, the phytoremediation capacity of various plant species and germplasm resources display significant genetic diversity, and the mechanisms underlying these differences remain hitherto obscure. Given its potential benefits, genetic improvement of plants is essential for enhancing their uptake of heavy metals, tolerance to harmful levels, as well as overall growth and development in contaminated soil. In this study, we uncover a molecular cascade that regulates cadmium (Cd2+) tolerance in cotton, involving GhRCD1, GhbHLH12, GhMYB44, and GhHMA1. We identified a Cd2+-sensitive cotton T-DNA insertion mutant with disrupted GhRCD1 expression. Genetic knockout of GhRCD1 by CRISPR/Cas9 technology resulted in reduced Cd2+ tolerance in cotton seedlings, while GhRCD1 overexpression enhanced Cd2+ tolerance. Through molecular interaction studies, we demonstrated that, in response to Cd2+ presence, GhRCD1 directly interacts with GhbHLH12. This interaction activates GhMYB44, which subsequently activates a heavy metal transporter, GhHMA1, by directly binding to a G-box cis-element in its promoter. These findings provide critical insights into a novel GhRCD1-GhbHLH12-GhMYB44-GhHMA1 regulatory module responsible for Cd2+ tolerance in cotton. Furthermore, our study paves the way for the development of elite Cd2+-tolerant cultivars by elucidating the molecular mechanisms governing the genetic control of Cd2+ tolerance in cotton.

Melatonin rescues the mitochondrial function of bone marrow-derived mesenchymal stem cells and improves the repair of osteoporotic bone defect in ovariectomized rats.

Osteoporotic bone defects, a severe complication of osteoporosis, are distinguished by a delayed bone healing process and poor repair quality. While bone marrow-derived mesenchymal stem cells (BMMSCs) are the primary origin of bone-forming osteoblasts, their mitochondrial function is impaired, leading to inadequate bone regeneration in osteoporotic patients. Melatonin is well-known for its antioxidant properties and regulation on bone metabolism. The present study postulated that melatonin has the potential to enhance the repair of osteoporotic bone defects by restoring the mitochondrial function of BMMSCs. In vitro administration of melatonin at varying concentrations (0.01, 1, and 100 µM) demonstrated a significant dose-dependent improvement in the mitochondrial function of BMMSCs obtained from ovariectomized rats (OVX-BMMSCs), as indicated by an elevation in mitochondrial membrane potential, adenosine triphosphate synthesis and expression of mitochondrial respiratory chain factors. Melatonin reduced the level of mitochondrial superoxide by activating the silent information regulator type 1 (SIRT1) and its downstream antioxidant enzymes, particularly superoxide dismutase 2 (SOD2). The protective effects of melatonin were found to be nullified upon silencing of Sirt1 or Sod2, underscoring the crucial role of the SIRT1-SOD2 axis in the melatonin-induced enhancement of mitochondrial energy metabolism in OVX-BMMSCs. To achieve a sustained and localized release of melatonin, silk fibroin scaffolds loaded with melatonin (SF@MT) were fabricated. The study involved the surgical creation of bilateral femur defects in OVX rats, followed by the implantation of SF@MT scaffolds. The results indicated that the application of melatonin partially restored the mitochondrial energy metabolism and osteogenic differentiation of OVX-BMMSCs by reinstating mitochondrial redox homeostasis. These findings suggest that the localized administration of melatonin through bone implants holds potential as a therapeutic approach for addressing osteoporotic bone defects.

Genome-wide identification and expression analysis of DREB family genes in cotton.

BACKGROUND: Dehydration responsive element-binding (DREB) transcription factors are widely present in plants, and involve in signalling transduction, plant growth and development, and stress response. DREB genes have been characterized in multiple species. However, only a few DREB genes have been studied in cotton, one of the most important fibre crops. Herein, the genome­wide identification, phylogeny, and expression analysis of DREB family genes are performed in diploid and tetraploid cotton species. RESULTS: In total, 193, 183, 80, and 79 putative genes containing the AP2 domain were identified using bioinformatics approaches in G. barbadense, G. hirsutum, G. arboretum, and G. raimondii, respectively. Phylogenetic analysis showed that based on the categorization of Arabidopsis DREB genes, 535 DREB genes were divided into six subgroups (A1-A6) by using MEGA 7.0. The identified DREB genes were distributed unevenly across 13/26 chromosomes of A and/or D genomes. Synteny and collinearity analysis confirmed that during the evolution, the whole genome duplications, segmental duplications, and/or tandem duplications occurred in cotton DREB genes, and then DREB gene family was further expanded. Further, the evolutionary trees with conserved motifs, cis-acting elements, and gene structure of cotton DREB gene family were predicted, and these results suggested that DREB genes might be involved in the hormone and abiotic stresses responses. The subcellular localization showed that in four cotton species, DREB proteins were predominantly located in the nucleus. Further, the analysis of DREB gene expression was carried out by real-time quantitative PCR, confirming that the identified DREB genes of cotton were involved in response to early salinity and osmotic stress. CONCLUSIONS: Collectively, our results presented a comprehensive and systematic understanding in the evolution of cotton DREB genes, and demonstrated the potential roles of DREB family genes in stress and hormone response.

Recent advances and future perspectives in early-maturing cotton research.

Cotton's fundamental requirements for long periods of growth and specific seasonal temperatures limit the global arable areas that can be utilized to cultivate cotton. This constraint can be alleviated by breeding for early-maturing varieties. By delaying the sowing dates without impacting the boll-opening time, early-maturing varieties not only mitigate the yield losses brought on by unfavorable weathers in early spring and late autumn but also help reducing the competition between cotton and other crops for arable land, thereby optimizing the cropping system. This review presents studies and breeding efforts for early-maturing cotton, which efficiently pyramid early maturity, high-quality, multiresistance traits, and suitable plant architecture by leveraging pleiotropic genes. Attempts are also made to summarize our current understanding of the molecular mechanisms underlying early maturation, which involves many pathways such as epigenetic, circadian clock, and hormone signaling pathways. Moreover, new avenues and effective measures are proposed for fine-scale breeding of early-maturing crops to ensure the healthy development of the agricultural industry.

GhRCD1 regulates cotton somatic embryogenesis by modulating the GhMYC3-GhMYB44-GhLBD18 transcriptional cascade.

Plant somatic embryogenesis (SE) is a multifactorial developmental process where embryos that can develop into whole plants are produced from somatic cells rather than through the fusion of gametes. The molecular regulation of plant SE, which involves the fate transition of somatic cells into embryogenic cells, is intriguing yet remains elusive. We deciphered the molecular mechanisms by which GhRCD1 interacts with GhMYC3 to regulate cell fate transitions during SE in cotton. While silencing of GhMYC3 had no discernible effect on SE, its overexpression accelerated callus formation, and proliferation. We identified two of GhMYC3 downstream SE regulators, GhMYB44 and GhLBD18. GhMYB44 overexpression was unconducive to callus growth but bolstered EC differentiation. However, GhLBD18 can be triggered by GhMYC3 but inhibited by GhMYB44, which positively regulates callus growth. On top of the regulatory cascade, GhRCD1 antagonistically interacts with GhMYC3 to inhibit the transcriptional function of GhMYC3 on GhMYB44 and GhLBD18, whereby a CRISPR-mediated rcd1 mutation expedites cell fate transition, resembling the effects of GhMYC3 overexpression. Furthermore, we showed that reactive oxygen species (ROS) are involved in SE regulation. Our findings elucidated that SE homeostasis is maintained by the tetrapartite module, GhRCD1-GhMYC3-GhMYB44-GhLBD18, which acts to modulate intracellular ROS in a temporal manner.

Genome-Wide Investigation and Co-Expression Network Analysis of SBT Family Gene in Gossypium.

Subtilases (SBTs), which belong to the serine peptidases, control plant development by regulating cell wall properties and the activity of extracellular signaling molecules, and affect all stages of the life cycle, such as seed development and germination, and responses to biotic and abiotic environments. In this study, 146 Gossypium hirsutum, 138 Gossypium barbadense, 89 Gossypium arboreum and 84 Gossypium raimondii SBTs were identified and divided into six subfamilies. Cotton SBTs are unevenly distributed on chromosomes. Synteny analysis showed that the members of SBT1 and SBT4 were expanded in cotton compared to Arabidopsis thaliana. Co-expression network analysis showed that six Gossypium arboreum SBT gene family members were in a network, among which five SBT1 genes and their Gossypium hirsutum and Arabidopsis thaliana direct homologues were down-regulated by salt treatment, indicating that the co-expression network might share conserved functions. Through co-expression network and annotation analysis, these SBTs may be involved in the biological processes of auxin transport, ABA signal transduction, cell wall repair and root tissue development. In summary, this study provides valuable information for the study of SBT genes in cotton and excavates SBT genes in response to salt stress, which provides ideas for cotton breeding for salinity resistance.

Efficient genotype-independent cotton genetic transformation and genome editing.

Cotton (Gossypium spp.) is one of the most important fiber crops worldwide. In the last two decades, transgenesis and genome editing have played important roles in cotton improvement. However, genotype dependence is one of the key bottlenecks in generating transgenic and gene-edited cotton plants through either particle bombardment or Agrobacterium-mediated transformation. Here, we developed a shoot apical meristem (SAM) cell-mediated transformation system (SAMT) that allowed the transformation of recalcitrant cotton genotypes including widely grown upland cotton (Gossypium hirsutum), Sea island cotton (Gossypium barbadense), and Asiatic cotton (Gossypium arboreum). Through SAMT, we successfully introduced two foreign genes, GFP and RUBY, into SAM cells of some recalcitrant cotton genotypes. Within 2-3 months, transgenic adventitious shoots generated from the axillary meristem zone could be recovered and grown into whole cotton plants. The GFP fluorescent signal and betalain accumulation could be observed in various tissues in GFP- and RUBY-positive plants, as well as in their progenies, indicating that the transgenes were stably integrated into the genome and transmitted to the next generation. Furthermore, using SAMT, we successfully generated edited cotton plants with inheritable targeted mutagenesis in the GhPGF and GhRCD1 genes through CRISPR/Cas9-mediated genome editing. In summary, the established SAMT transformation system here in this study bypasses the embryogenesis process during tissue culture in a conventional transformation procedure and significantly accelerates the generation of transgenic and gene-edited plants for genetic improvement of recalcitrant cotton varieties.

Cotton D genome assemblies built with long-read data unveil mechanisms of centromere evolution and stress tolerance divergence.

BACKGROUND: Many of genome features which could help unravel the often complex post-speciation evolution of closely related species are obscured because of their location in chromosomal regions difficult to accurately characterize using standard genome analysis methods, including centromeres and repeat regions. RESULTS: Here, we analyze the genome evolution and diversification of two recently diverged sister cotton species based on nanopore long-read sequence assemblies and Hi-C 3D genome data. Although D genomes are conserved in gene content, they have diversified in gene order, gene structure, gene family diversification, 3D chromatin structure, long-range regulation, and stress-related traits. Inversions predominate among D genome rearrangements. Our results support roles for 5mC and 6mA in gene activation, and 3D chromatin analysis showed that diversification in proximal-vs-distal regulatory-region interactions shape the regulation of defense-related-gene expression. Using a newly developed method, we accurately positioned cotton centromeres and found that these regions have undergone obviously more rapid evolution relative to chromosome arms. We also discovered a cotton-specific LTR class that clarifies evolutionary trajectories among diverse cotton species and identified genetic networks underlying the Verticillium tolerance of Gossypium thurberi (e.g., SA signaling) and salt-stress tolerance of Gossypium davidsonii (e.g., ethylene biosynthesis). Finally, overexpression of G. thurberi genes in upland cotton demonstrated how wild cottons can be exploited for crop improvement. CONCLUSIONS: Our study substantially deepens understanding about how centromeres have developed and evolutionarily impacted the divergence among closely related cotton species and reveals genes and 3D genome structures which can guide basic investigations and applied efforts to improve crops.

Effects of Extraction Technique on the Content and Antioxidant Activity of Flavonoids from Gossypium Hirsutum linn. Flowers.

Cotton is one of the Uyghur medical materials in China and is rich in flavonoids. Flavonoids have important pharmacological effects. The yield of flavonoids in traditional extraction methods is low, which affects the development of flavonoids. Therefore, it is urgent to optimize the extraction techniques. The yield of flavonoids in cotton flowers was effectively improved by response surface methodology, and the highest yield of flavonoids reached 5.66%, and the optimal extraction process conditions were obtained. The DPPH free radical scavenging rate, hydroxyl free radical scavenging rate, superoxide anion free radical scavenging rate, and reducing ability were tested to reflect the antioxidant capacity of flavonoids. The flavonoids had an excellent antioxidant effect. Cell experiments suggested that the flavonoids had the effect of protecting glutamate-induced damage to HT-22 cells. The results of this study provide a theoretical basis for the extraction of cotton flowers flavonoids and the comprehensive evaluation of antioxidant products, as well as the extraction of other plant flavonoids.

BIN2 negatively regulates plant defence against Verticillium dahliae in Arabidopsis and cotton.

Verticillium wilt is caused by the soil-borne vascular pathogen Verticillium dahliae, and affects a wide range of economically important crops, including upland cotton (Gossypium hirsutum). Previous studies showed that expression levels of BIN2 were significantly down-regulated during infestation with V. dahliae. However, the underlying molecular mechanism of BIN2 in plant regulation against V. dahliae remains enigmatic. Here, we characterized a protein kinase GhBIN2 from Gossypium hirsutum, and identified GhBIN2 as a negative regulator of resistance to V. dahliae. The Verticillium wilt resistance of Arabidopsis and cotton were significantly enhanced when BIN2 was knocked down. Constitutive expression of BIN2 attenuated plant resistance to V. dahliae. We found that BIN2 regulated plant endogenous JA content and influenced the expression of JA-responsive marker genes. Further analysis revealed that BIN2 interacted with and phosphorylated JAZ family proteins, key repressors of the JA signalling pathway in both Arabidopsis and cotton. Spectrometric analysis and site-directed mutagenesis showed that BIN2 phosphorylated AtJAZ1 at T196, resulting in the degradation of JAZ proteins. Collectively, these results show that BIN2 interacts with JAZ proteins and plays a negative role in plant resistance to V. dahliae. Thus, BIN2 may be a potential target gene for genetic engineering against Verticillium wilt in crops.

The miR164-GhCUC2-GhBRC1 module regulates plant architecture through abscisic acid in cotton.

Branching determines cotton architecture and production, but the underlying regulatory mechanisms remain unclear. Here, we report that the miR164-GhCUC2 (CUP-SHAPED COTYLEDON2) module regulates lateral shoot development in cotton and Arabidopsis. We generated OE-GhCUC2m (overexpression GhCUC2m) and STTM164 (short tandem target mimic RNA of miR164) lines in cotton and heterologous expression lines for gh-miR164, GhCUC2 and GhCUC2m in Arabidopsis to study the mechanisms controlling lateral branching. GhCUC2m overexpression resulted in a short-branch phenotype similar to STTM164. In addition, heterologous expression of GhCUC2m led to decreased number and length of branches compared with wild type, opposite to the effects of the OE-gh-pre164 line in Arabidopsis. GhCUC2 interacted with GhBRC1 and exhibited similar negative regulation of branching. Overexpression of GhBRC1 in the brc1-2 mutant partially rescued the mutant phenotype and decreased branch number. GhBRC1 directly bound to the NCED1 promoter and activated its transcription, leading to local abscisic acid (ABA) accumulation and response. Mutation of the NCED1 promoter disrupted activation by GhBRC1. This finding demonstrates a direct relationship between BRC1 and ABA signalling and places ABA downstream of BRC1 in the control of branching development. The miR164-GhCUC2-GhBRC1-GhNCED1 module provides a clear regulatory axis for ABA signalling to control plant architecture.

Transcriptome Analysis Revealed GhWOX4 Intercedes Myriad Regulatory Pathways to Modulate Drought Tolerance and Vascular Growth in Cotton.

Cotton is a paramount cash crop around the globe. Among all abiotic stresses, drought is a leading cause of cotton growth and yield loss. However, the molecular link between drought stress and vascular growth and development is relatively uncharted. Here, we validated a crucial role of GhWOX4, a transcription factor, modulating drought stress with that of vasculature growth in cotton. Knock-down of GhWOX4 decreased the stem width and severely compromised vascular growth and drought tolerance. Conversely, ectopic expression of GhWOX4 in Arabidopsis enhanced the tolerance to drought stress. Comparative RNAseq analysis revealed auxin responsive protein (AUX/IAA), abscisic acid (ABA), and ethylene were significantly induced. Additionally, MYC-bHLH, WRKY, MYB, homeodomain, and heat-shock transcription factors (HSF) were differentially expressed in control plants as compared to GhWOX4-silenced plants. The promotor zone of GhWOX4 was found congested with plant growth, light, and stress response related cis-elements. differentially expressed genes (DEGs) related to stress, water deprivation, and desiccation response were repressed in drought treated GhWOX4-virus-induced gene silencing (VIGS) plants as compared to control. Gene ontology (GO) functions related to cell proliferation, light response, fluid transport, and flavonoid biosynthesis were over-induced in TRV: 156-0 h/TRV: 156-1 h (control) in comparison to TRV: VIGS-0 h/TRV: VIGS-1 h (GhWOX4-silenced) plants. This study improves our context for elucidating the pivotal role of GhWOX4 transcription factors (TF), which mediates drought tolerance, plays a decisive role in plant growth and development, and is likely involved in different regulatory pathways in cotton.

Mutation of key amino acids in the polygalacturonase-inhibiting proteins CkPGIP1 and GhPGIP1 improves resistance to Verticillium wilt in cotton.

Verticillium wilt, one of the most devastating diseases of cotton (Gossypium hirsutum), causes severe yield and quality losses. Given the effectiveness of plant polygalacturonase-inhibiting proteins (PGIPs) in reducing fungal polygalacturonase (PG) activity, it is necessary to uncover the key functional amino acids to enhance cotton resistance to Verticillium dahliae. To identify novel antifungal proteins, the selectivity of key amino acids was investigated by screening against a panel of relevant PG-binding residues. Based on the obtained results, homologous models of the mutants were established. The docking models showed that hydrogen bonds and structural changes in the convex face in the conserved portion of leucine-rich repeats (LRRs) may be essential for enhanced recognition of PG. Additionally, we successfully constructed Cynanchum komarovii PGIP1 (CkPGIP1) mutants Asp176Val, Pro249Gln, and Asp176Val/Pro249Gln and G. hirsutum PGIP1 (GhPGIP1) mutants Glu169Val, Phe242Gln, and Glu169Val/Phe242Gln with site-directed mutagenesis. The proteins of interest can effectively inhibit VdPG1 activity and V. dahliae mycelial growth in a dose-dependent manner. Importantly, mutants that overproduced PGIP in Arabidopsis and cotton showed enhanced resistance to V. dahliae, with reduced Verticillium-associated chlorosis and wilting. Furthermore, the lignin content was measured in mutant-overexpressing plants, and the results showed enhanced lignification of the xylem, which blocked the spread of V. dahliae. Thus, using site-directed mutagenesis assays, we showed that mutations in CkPGIP1 and GhPGIP1 give rise to PGIP versatility, which allows evolving recognition specificities for PG and is required to promote Verticillium resistance in cotton by restricting the growth of invasive fungal pathogens.

BR deficiency causes increased sensitivity to drought and yield penalty in cotton.

BACKGROUND: Brassinosteroids (BRs) play crucial roles in drought tolerance, but the underlying molecular mechanisms remain unclear in the important oilseed and fiber crop, cotton (Gossypium hirsutum L.). RESULTS: To elucidate how BRs mediate drought tolerance in cotton, a cotton brassinosteroid (BR)-deficient mutant, pag1 (pagoda1), was employed for analysis. Importantly, the pag1 mutant showed increased sensitivity to drought stress, with shorter primary roots and fewer lateral roots. The number of stomata was significantly increased in the mutant, and the stomata aperture was much wider than that of the control plants. These mutant plants therefore showed an increased water loss rate. Furthermore, the abscisic acid (ABA) content, photosynthetic efficiency and starch content of the mutant were significantly lower than those of the wild type. The overall performance of the mutant plants was worse than that of the wild-type control under both normal and drought conditions. Moreover, Proteomic analysis revealed reduced levels of stress-related proteins in pag1 plants. CONCLUSIONS: These results suggest that BRs may modulate the drought tolerance of cotton by regulating much genes that related to drought stress and multiple organ responses to drought, including root growth, stomata development, the stomata aperture and photosynthesis. This study provides an important basis for understanding drought resistance regulated by BRs and cultivating drought-resistant cotton lines.

The cotton GhWIN2 gene activates the cuticle biosynthesis pathway and influences the salicylic and jasmonic acid biosynthesis pathways.

BACKGROUND: Metabolic pathways are interconnected and yet relatively independent. Genes involved in metabolic modules are required for the modules to run. Study of the relationships between genes and metabolic modules improves the understanding of metabolic pathways in plants. The WIN transcription factor activates the cuticle biosynthesis pathway and promotes cuticle biosynthesis. The relationship between the WIN transcription factor and other metabolic pathways is unknown. Our aim was to determine the relationships between the main genes involved in cuticle biosynthesis and those involved in other metabolic pathways. We did this by cloning a cotton WIN gene, GhWIN2, and studying its influence on other pathways. RESULTS: As with other WIN genes, GhWIN2 regulated expression of cuticle biosynthesis-related genes, and promoted cuticle formation. Silencing of GhWIN2 resulted in enhanced resistance to Verticillium dahliae, caused by increased content of salicylic acid (SA). Moreover, silencing of GhWIN2 suppressed expression of jasmonic acid (JA) biosynthesis-related genes and content. GhWIN2 positively regulated the fatty acid biosynthesis pathway upstream of the JA biosynthesis pathway. Silencing of GhWIN2 reduced the content of stearic acid, a JA biosynthesis precursor. CONCLUSIONS: GhWIN2 not only regulated the cuticle biosynthesis pathway, but also positively influenced JA biosynthesis and negatively influenced SA biosynthesis.