摘要：
Upland cotton, the mainly cultivated cotton species in the world, provides over 90% of natural raw materials (fibers) for the textile industry. The development of cotton fibers that are unicellular and highly elongated trichomes on seeds is a delicate and complex process. However, the regulatory mechanism of fiber development is still largely unclear in detail. In this study, we report that a homeodomain-leucine zipper (HD-ZIP) IV transcription factor, GhHOX4, plays an important role in fiber elongation. Overexpression of GhHOX4 in cotton resulted in longer fibers, while GhHOX4-silenced transgenic cotton displayed a "shorter fiber" phenotype compared with wild type. GhHOX4 directly activates two target genes, GhEXLB1D and GhXTH2D, for promoting fiber elongation. On the other hand, phosphatidic acid (PA), which is associated with cell signaling and metabolism, interacts with GhHOX4 to hinder fiber elongation. The basic amino acids KR-R-R in START domain of GhHOX4 protein are essential for its binding to PA that could alter the nuclear localization of GhHOX4 protein, thereby suppressing the transcriptional regulation of GhHOX4 to downstream genes in the transition from fiber elongation to secondary cell wall (SCW) thickening during fiber development. Thus, our data revealed that GhHOX4 positively regulates fiber elongation, while PA may function in the phase transition from fiber elongation to SCW formation by negatively modulating GhHOX4 in cotton.
摘要：
Drought stress impairs crop growth and development. BEL1-like family transcription factors may be involved in plant response to drought stress, but little is known of the molecular mechanism by which these proteins regulate plant response and defense to drought stress. Here we show that the BEL1-like transcription factor GhBLH5-A05 functions in cotton (Gossypium hirsutum) response and defense to drought stress. Expression of GhBLH5-A05 in cotton was induced by drought stress. Overexpression of GhBLH5-A05 in both Arabidopsis and cotton increased drought tolerance, whereas silencing GhBLH5A05 in cotton resulted in elevated sensitivity to drought stress. GhBLH5-A05 binds to cis elements in the promoters of GhRD20-A09 and GhDREB2C-D05 to activate the expression of these genes. GhBLH5A05 interacted with the KNOX transcription factor GhKNAT6-A03. Co -expression of GhBLH5-A05 and GhKNAT6-A03 increased the transcription of GhRD20-A09 and GhDREB2C-D05. We conclude that GhBLH5-A05 acts as a regulatory factor with GhKNAT6-A03 functioning in cotton response to drought stress by activating the expression of the drought-responsive genes GhRD20-A09 and GhDREB2C-D05. (c) 2023 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY -NCND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
期刊：
JOURNAL OF EXPERIMENTAL BOTANY,2023年74(6):1836-1852 ISSN：0022-0957
通讯作者：
Yang Li<&wdkj&>Xue-Bao Li
作者机构：
[Wang, Yao; Li, Yu; Zheng, Yong; Li, Xue-Bao; Zhang, Shi-Peng; Li, Yang; Cheng, Fan] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.
通讯机构：
[Yang Li; Xue-Bao Li] H;Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University , Wuhan 430079 , China
摘要：
Cotton fiber elongation is a critical growth phase that affects final fiber length. Morphological analysis indicated an asynchronous fiber elongation pattern between two cotton varieties, J7-1 and J14-1. Through phosphoproteomic analysis, a total of 89 differentially-phosphorylated proteins (DPPs) were identified in elongating fibers between J7-1 and J14-1. Gene ontology (GO) analysis showed that these DPPs were mainly enriched in sucrose synthase activity, transferase activity, and UDP-glycosyltransferase activity. In J14-1, the phosphorylation level of GhSUS2, a key sucrose synthase in the sucrose metabolism pathway, was significantly higher than that in J7-1. We further revealed that GhSUS2 positively regulates fiber elongation, and GhSUS2-silenced transgenic cotton displayed the phenotype of 'short fibers' compared with the controls. During fiber development, the residue Ser11 in the GhSUS2 protein is phosphorylated by the Ca2+-dependent protein kinases GhCPK84 and GhCPK93. Phosphorylated GhSUS2 is localized in the cytoplasm, whereas unphosphorylated GhSUS2 is localized in the plasma membrane. Moreover, abscisic acid (ABA) could promote the transcription and translation of GhCPK84 and GhCPK93, thereby enhancing the phosphorylation of GhSUS2 to impede fiber elongation. Thus, our data demonstrates that GhSUS2 plays a positive role in fiber development, but its phosphorylation by GhCPK84 and GhCPK93 hinders fiber elongation of cotton.
作者机构：
[Wang, Yao; Zheng, Yong; He, Shao-Ping; Xu, Shang-Wei; Li, Xue-Bao; Li, XB; Li, Yang; Zheng, Y] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.;[Li, Li; Li, L] Huazhong Agr Univ, Coll Biomed & Hlth, Wuhan 430070, Peoples R China.;[Li, Li; Li, L] Huazhong Agr Univ, Coll Life Sci & Technol, Wuhan 430070, Peoples R China.;[Wang, Yao] Sichuan Agr Univ, Maize Res Inst, Wenjiang 611130, Sichuan, Peoples R China.
通讯机构：
[Li, XB ; Zheng, Y] C;[Li, L ] H;Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.;Huazhong Agr Univ, Coll Biomed & Hlth, Wuhan 430070, Peoples R China.;Huazhong Agr Univ, Coll Life Sci & Technol, Wuhan 430070, Peoples R China.
摘要：
Transcription factors GhERF108 and GhARF7 interact to establish ethylene-auxin crosstalk, which activates downstream secondary cell wall (SCW)-related genes to facilitate fiber SCW formation in cotton. Phytohormones play indispensable roles in plant growth and development. However, the molecular mechanisms underlying phytohormone-mediated regulation of fiber secondary cell wall (SCW) formation in cotton (Gossypium hirsutum) remain largely underexplored. Here, we provide mechanistic evidence for functional interplay between the APETALA2/ethylene response factor (AP2/ERF) transcription factor GhERF108 and auxin response factors GhARF7-1 and GhARF7-2 in dictating the ethylene-auxin signaling crosstalk that regulates fiber SCW biosynthesis. Specifically, in vitro cotton ovule culture revealed that ethylene and auxin promote fiber SCW deposition. GhERF108 RNA interference (RNAi) cotton displayed remarkably reduced cell wall thickness compared with controls. GhERF108 interacted with GhARF7-1 and GhARF7-2 to enhance the activation of the MYB transcription factor gene GhMYBL1 (MYB domain-like protein 1) in fibers. GhARF7-1 and GhARF7-2 respond to auxin signals that promote fiber SCW thickening. GhMYBL1 RNAi and GhARF7-1 and GhARF7-2 virus-induced gene silencing (VIGS) cotton displayed similar defects in fiber SCW formation as GhERF108 RNAi cotton. Moreover, the ethylene and auxin responses were reduced in GhMYBL1 RNAi plants. GhMYBL1 directly binds to the promoters of GhCesA4-1, GhCesA4-2, and GhCesA8-1 and activates their expression to promote cellulose biosynthesis, thereby boosting fiber SCW formation. Collectively, our findings demonstrate that the collaboration between GhERF108 and GhARF7-1 or GhARF7-2 establishes ethylene-auxin signaling crosstalk to activate GhMYBL1, ultimately leading to the activation of fiber SCW biosynthesis.
摘要：
Cotton which produces natural fiber materials for the textile industry is one of the most important crops in the world. Class II KNOX proteins are often considered as transcription factors in regulating plant secondary cell wall (SCW) formation. However, the molecular mechanism of the KNOX transcription factor-regulated SCW synthesis in plants (especially in cotton) remains unclear in details so far. In this study, we show a cotton class II KNOX protein (GhKNL1) as a transcription repressor functioning in fiber development. The GhKNL1-silenced transgenic cotton produced longer fibers with thicker SCWs, whereas GhKNL1 dominant repression transgenic lines displayed the opposite fiber phenotype, compared with controls. Further experiments revealed that GhKNL1 could directly bind to promoters of GhCesA4-2/4-4/8-2 and GhMYB46 for modulating cellulose synthesis during fiber SCW development in cotton. On the other hand, GhKNL1 could also suppress expressions of GhEXPA2D/4A-1/4D-1/13A through binding to their promoters for regulating fiber elongation of cotton. Taken together, these data revealed GhKNL1 functions in fiber elongation and SCW formation by directly repressing expressions of its target genes related to cell elongation and cellulose synthesis. Thus, our data provide an effective clue for potentially improving fiber quality by genetic manipulation of GhKNL1 in cotton breeding.
作者机构：
[Wang, Huan; Zheng, Yong; Li, Xue-Bao; Fu, Yi-Fan; Huang, Ke-Lin; Tian, Jing; Li, Yang] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.
通讯机构：
[Xue-Bao Li] H;Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University , Wuhan 430079, China
摘要：
Sugar is considered as the primary regulator of plant apical dominance, whereby the outgrowth of axillary buds is inhibited by the shoot tip. However, there are some deficiencies in this theory. Here, we reveal that Fatty Acid Export 6 (BnFAX6) functions in FA transport, and linoleic acid or its derivatives acts as a signaling molecule in regulating apical dominance of Brassica napus. BnFAX6 is responsible for mediating FA export from plastids. Overexpression of BnFAX6 in B. napus heightened the expression of genes involved in glycolysis and lipid biosynthesis, promoting the flow of photosynthetic products to the biosynthesis of FAs (including linoleic acid and its derivatives). Enhancing expression of BnFAX6 increased oil content in seeds and leaves and resulted in semi-dwarf and increased branching phenotypes with more siliques, contributing to increased yield per plant relative to wild-type. Furthermore, decapitation led to the rapid flow of the carbon from photosynthetic products to FA biosynthesis in axillary buds, consistent with the overexpression of BnFAX6 in B. napus. In addition, free FAs, especially linoleic acid, were rapidly transported from leaves to axillary buds. Increasing linoleic acid in axillary buds repressed expression of a key transcriptional regulator responsible for maintaining bud dormancy, resulting in bud outgrowth. Taken together, we uncovered that BnFAX6 mediating FA export from plastids functions in lipid biosynthesis and in axillary bud dormancy release, possibly through enhancing linoleic acid level in axillary buds of B. napus.
作者机构：
[Wei, Ning; Liu, Zhi-Hao; Zheng, Yong; Zhang, Jing-Bo; Li, Xue-Bao; Chen, Yun; Li, Yang] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.;[Liu, Zhi-Hao; Chen, Yun] Hubei Normal Univ, Sch Life Sci, Huangshi 435002, Hubei, Peoples R China.
通讯机构：
[Li, Xue-Bao] H;Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China.
关键词：
Cotton (Gossypium hirsutum);Drought stress;Type-2C protein phosphatase (PP2C);Regulation of gene expression;Abscisic acid (ABA) signaling;Plant drought tolerance
摘要：
GhDRP1 acts as a negatively regulator to participate in response to drought stress possibly by modulating ABA signaling pathway and flavonoid biosynthesis pathway which affects stomata movement and thus water loss, ROS scavenging enzymes, and proline accumulation in cotton. Type-2C protein phosphatases (PP2C) may play important roles in plant stress signal transduction. Here, we show the evidence that a cotton PP2C protein GhDRP1 participates in plant response to drought stress. GhDRP1 gene encodes an active type-2C protein phosphatase (PP2C) and its expression is significantly induced in cotton by drought stress. Compared with wild type, the GhDRP1 overexpression (OE) transgenic cotton and Arabidopsis displayed reduced drought tolerance, whereas GhDRP1-silenced (RNAi) cotton showed enhanced drought tolerance. Under drought stress, malondialdehyde content was lower, whereas superoxide dismutase and peroxidase activities, proline content, stomata closure and relative water content were higher in GhDRP1 RNAi plants compared with those in wild type. In contrast, GhDRP1 OE plants showed the opposite phenotype under the same conditions. Expression levels of some stress-related and flavonoid biosynthesis-related genes were altered in GhDRP1 transgenic plants under drought stress. Additionally, GhDRP1 protein could interact with other proteins such as PYLs, SNF1-related protein kinase and GLK1-like protein. Collectively, these data suggest that GhDRP1 participates in plant response to drought stress possibly by modulating ABA signaling pathway and flavonoid biosynthesis pathway which affects stomata movement and thus water loss, ROS scavenging enzymes, and proline accumulation in cotton.
作者机构：
[Wang, Yao; Zheng, Yong; Wang, Na-Na; Chen, Yi-Hao; Zhou, Li; Lu, Rui; Li, Xue-Bao; Li, Yang] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.;[Wang, Na-Na] Anhui Agr Univ, Sch Life Sci, Hefei 230036, Peoples R China.
通讯机构：
[Yong Zheng; Xue-Bao Li] H;Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University , Wuhan 430079, China
摘要：
Cotton, one of the most important crops in the world, produces natural fiber materials for the textile industry. WRKY transcription factors play important roles in plant development and stress responses. However, little is known about whether and how WRKY transcription factors regulate fiber development of cotton so far. In this study, we show that a fiber-preferential WRKY transcription factor, GhWRKY16, positively regulates fiber initiation and elongation. GhWRKY16-silenced transgenic cotton displayed a remarkably reduced number of fiber protrusions on the ovule and shorter fibers compared to the wild-type. During early fiber development, GhWRKY16 directly binds to the promoters of GhHOX3, GhMYB109, GhCesA6D-D11, and GhMYB25 to induce their expression, thereby promoting fiber initiation and elongation. Moreover, GhWRKY16 is phosphorylated by the mitogen-activated protein kinase GhMPK3-1 at residues T-130 and S-260. Phosphorylated GhWRKY16 directly activates the transcription of GhMYB25, GhHOX3, GhMYB109, and GhCesA6D-D11 for early fiber development. Thus, our data demonstrate that GhWRKY16 plays a crucial role in fiber initiation and elongation, and that GhWRKY16 phosphorylation by GhMPK3-1 is essential for the transcriptional activation on downstream genes during the fiber development of cotton.
摘要：
Acetylation and deacetylation of histones are important for regulating a series of biological processes in plants. Histone deacetylases (HDACs) control the histone deacetylation that plays an important role in plant response to abiotic stress. In our study, we show the evidence that GhHDT4D (a member of the HD2 subfamily of HDACs) is involved in cotton (Gossypium hirsutum) response to drought stress. Overexpression of GhHDT4D in Arabidopsis increased plant tolerance to drought, whereas silencing GhHDT4D in cotton resulted in plant sensitivity to drought. Simultaneously, the H3K9 acetylation level was altered in the GhHDT4D silenced cotton, compared with the controls. Further study revealed that GhHDT4D suppressed the transcription of GhWRKY33, which plays a negative role in cotton defense to drought, by reducing its H3K9 acetylation level. The expressions of the stress-related genes, such as GhDREB2A, GhDREB2C, GhSOS2, GhRD20-1, GhRD20-2 and GhRD29A, were significantly decreased in the GhHDT4D silenced cotton, but increased in the GhWRKY33 silenced cotton. Given these data together, our findings suggested that GhHDT4D may enhance drought tolerance by suppressing the expression of GhWRKY33, thereby activating the downstream drought response genes in cotton.
作者机构：
[Zheng, Yong; Chen, Yi-Hao; Wang, Na-Na; Zhang, Jing-Bo; Li, Xue-Bao] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.
通讯机构：
[Li, Xue-Bao] C;Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.
关键词：
Cotton (gossypium hirsutum);Mitogen-activated protein kinase (MAPK);Fiber elongation;Phosphorylation;Phytohormone signaling
摘要：
Key message 56 MAPK genes were identified in upland cotton genome, and unequally distribute on 22 chromosomes of cotton genome. They can be divided into 4 groups, and the TEY type of T-loop exists in A, B and C groups, but the TDY type of T-loop is only in group D. Furthermore, GhMPK6 may be involved in phosphorylation of its downstream proteins for regulating fiber elongation of cotton. Mitogen-activated protein kinases (MAPKs) are important in regulating plant development as well as stress response. In this study, we genome-widely identified 56 MAPK genes in upland cotton. These MAPK genes unequally distribute on 22 chromosomes of cotton genome, but no MAPK gene is located on At_Chr6, Dt_Chr6, At_Chr13 and Dt_Chr13. The exons and introns in GhMAPK gene family vary widely at the position, number and length. Furthermore, GhMAPK family can be divided into 4 groups (A, B, C and D), and the TEY type of T-loop exists in three groups (A, B and C), but the TDY type of T-loop is only in group D. Further study revealed that some GhMAPK genes (including GhMPK6) are preferentially expressed in elongating fibers. GhMPK6 maintains a high phosphorylation level in elongating fibers, and its phosphorylation was enhanced in fibers by phytohormones brassinosteroid (BR), ethylene and indole-3-acetic acid (IAA). Additionally, GhMPK6 could interact with GhMKK2-2 and GhMKK4, suggesting that GhMKK2-2/4-GhMPK6 module may be involved in phosphorylation of its downstream proteins for regulating fiber elongation of cotton.
作者机构：
[Wang, Yao; Wu, Yu-Wei; Wang, Na-Na; Lu, Rui; Li, Xue-Bao; Wang, Ya-Chao; Li, Yang] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.;[Li, Li] Univ Toronto, Hosp Sick Children, Arthur & Sonia Labatt Brain Tumor Res Ctr, Dept Genet & Genome Biol, Toronto, ON M5G 0A4, Canada.;[Li, Li] Univ Toronto, Toronto, ON M5G 0A4, Canada.
通讯机构：
[Li, Xue-Bao] C;Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Peoples R China.
摘要：
Spatiotemporally regulated callose deposition is an essential, genetically programmed phenomenon that promotes pollen development and functionality. Severe male infertility is associated with deficient callose biosynthesis, highlighting the significance of intact callose deposition in male gametogenesis. The molecular mechanism that regulates the crucial role of callose in production of functional male gametophytes remains completely unexplored. Here, we provide evidence that the gradual upregulation of a previously uncharacterized cotton (Gossypium hirsutum) pollen-specific SKS-like protein (PSP231), specifically at the post pollen-mitosis stage, activates callose biosynthesis to promote pollen maturation. Aberrant PSP231 expression levels caused by either silencing or overexpression resulted in late pollen developmental abnormalities and male infertility phenotypes in a dose-dependent manner, highlighting the importance of fine-tuned PSP231 expression. Mechanistic analyses revealed that PSP231 plays a central role in triggering and fine-tuning the callose synthesis and deposition required for pollen development. Specifically, PSP231 protein sequesters the cellular pool of RNA-binding protein GhRBPL1 to destabilize GhWRKY15 mRNAs, turning off GhWRKY15-mediated transcriptional repression of GhCalS4/GhCalS8 and thus activating callose biosynthesis in pollen. This study showed that PSP231 is a key molecular switch that activates the molecular circuit controlling callose deposition toward pollen maturation and functionality and thereby safeguards agricultural crops against male infertility.
作者机构：
[Li, Yang; Li, Xue-Bao; Wang, Na-Na; Zhou, Li; Xu, Shang-Wei; Sun, Yun-Lue; Liu, Dong] Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Li, Y; Li, XB] C;Cent China Normal Univ, Sch Life Sci, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan 430079, Hubei, Peoples R China.
摘要：
As the important source of natural fibers in the textile industry, cotton fiber quality and yield are often restricted to drought conditions because most of cotton plants in the world grow in the regions with water shortage. WRKY transcription factors regulate multiple plant physiological processes, including drought stress response. However, little is known of how the WRKY genes respond to drought stress in cotton. Our previous study revealed GhWRKY33 is leaf-specific and induced by drought stress. In this study, our data showed GhWRKY33 protein localizes to the cell nucleus and is able to bind to "W-box" cis-acting elements of the target promoters. Under drought stress, GhWRKY33 overexpressing transgenic Arabidopsis was withered much more quickly than wild type due to faster water loss. Moreover, GhWRKY33 transgenic plants displayed more tolerance to abscisic acid (ABA), relative to wild type. Expression of some drought stress-related genes and ABA-responsive genes were changed in the GhWRKY33 transgenic Arabidopsis with drought or ABA treatment. Collectively, our findings indicate that GhWRKY33 may act as a negative regulator to mediate plant response to drought stress and to participate in the ABA signaling pathway.
摘要：
Anther/pollen development is a highly programmed process in flowering plants. However, the molecular mechanism of regulating anther/pollen development is still largely unclear so far. Here, we report a cotton WRKY transcription factor (GhWRKY22) that functions in anther/pollen development. Quantitative RT-PCR and GUS activity analyses revealed that GhWRKY22 is predominantly expressed in the late developing anther/pollen of cotton. The transgenic Arabidopsis plants expressing GhWRKY22 displayed the male fertility defect with the fewer viable pollen grains. Expression of the genes involved in jasmonate (JA) biosynthesis was up-regulated, whereas expression of the JA-repressors (JAZ1 and JAZ8) was down-regulated in the transgenic Arabidopsis plants expressing GhWRKY22, compared with those in wild type. Yeast one-hybrid and ChIP-qPCR assays demonstrated that GhWRKY22 modulated the expression of JAZ genes by directly binding to their promoters for regulating anther/pollen development. Yeast two-hybrid assay indicated that GhMYB24 could interact with GhJAZ8-A and GhJAZ13-A. Furthermore, expression of AtMYB24, AtPAL2 and AtANS2 was enhanced in the transgenic Arabidopsis plants, owing to GhWRKY22 overexpression. Taking the data together, our results suggest that GhWRKY22 acts as a transcriptional repressor to regulate anther/pollen development possibly by modulating the expression of the JAZ genes.
摘要：
MYB proteins represent one of the largest transcription factor (TF) families in plants, some of which act as key transcriptional regulators of secondary cell wall (SCW) biosynthesis. Cotton (Gossypium hirsutum) fiber is thought to be an ideal single-cell model to study cell elongation and SCW biosynthesis. However, little knowledge regarding the TFs controlling fiber SCW biosynthesis, particularly for R2R3-MYBs is known. By far, no comprehensive genome-wide analysis of the secondary wall-associated R2R3-MYBs has been reported in cultivated tetraploid upland cotton. In this study, we identified 419 R2R3-MYB genes by systematically examining the cotton genome. A combination of phylogenetic, RNA-seq and co-expression analyses indicated that 36 R2R3-MYBs were either preferentially or highly expressed in 20 day post anthesis (dpa) fibers and are putative SCW regulators. Among these MYB genes, 22 MYBs are homologs of known SCW MYB proteins and the other 14 MYBs are novel proteins without prior reported SCW biosynthesis-related functions. Finally, we highlighted on the roles of two MYBs named GhMYB46_D13 and GhMYB46_D9, both of which displayed the highest expression in 20 dpa fibers. Expression of GhMYB46_D13 or GhMYB46_D9 individually in Arabidopsis resulted in ectopic SCW deposition in transgenic plants. Furthermore, both GhMYB46_D13 and GhMYB46_D9 were able to activate the cotton fiber SCW cellulose synthase gene promoters. Thus, we have identified 36 R2R3-MYBs as potential SCW regulators in cotton fibers that represent strong candidates for further functional studies during fiber development and SCW thickening.
