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[学术文献 ] CYTOKININ DEHYDROGENASE suppression increases intrinsic water-use efficiency and photosynthesis in cotton under drought 进入全文
PLANT PHYSIOLOGY
Drought reduces endogenous cytokinin (CK) content and disturbs plant water balance and photosynthesis. However, the effect of higher endogenous CK levels (achieved by suppressing cytokinin dehydrogenase [CKX] genes) on plant water status and photosynthesis under drought stress is unknown. Here, pot experiments were conducted with wild-type (WT) cotton (Gossypium hirsutum) and 2 GhCKX suppression lines (CR-3 and CR-13) to explore the effect of higher endogenous CK levels on leaf water utilization and photosynthesis under drought stress. The GhCKX suppression lines had a higher leaf net photosynthetic rate (AN) and intrinsic water-use efficiency (iWUE) than WT under drought. This increase was attributed to the decoupling of stomatal conductance (gs) and mesophyll conductance (gm) in the suppression lines in response to drought. GhCKX suppression increased gm but maintained gs relative to WT under drought, and the increased gm was associated with altered anatomical traits, including decreased cell wall thickness (Tcw) and increased surface area of chloroplast-facing intercellular airspaces per unit leaf area (Sc/S), as well as altered cell wall composition, especially decreased cellulose levels. This study provides evidence that increased endogenous CK levels can simultaneously enhance AN and iWUE in cotton under drought conditions and establishes a potential mechanism for this effect. These findings provide a potential strategy for breeding drought-tolerant crops or exploring alternative methods to promote crop drought tolerance. Increasing endogenous cytokinin levels alters anatomical traits related to stomatal and mesophyll conductance, resulting in their decoupling and enhanced drought tolerance in cotton.
[学术文献 ] A cell fractionation and quantitative proteomics pipeline to enable functional analyses of cotton fiber development 进入全文
PLANT JOURNAL
Cotton fibers are aerial trichoblasts that employ a highly polarized diffuse growth mechanism to emerge from the developing ovule epidermis. After executing a complicated morphogenetic program, the cells reach lengths over 2 cm and serve as the foundation of a multi-billion-dollar textile industry. Important traits such as fiber diameter, length, and strength are defined by the growth patterns and cell wall properties of individual cells. At present, the ability to engineer fiber traits is limited by our lack of understanding regarding the primary controls governing the rate, duration, and patterns of cell growth. To gain insights into the compartmentalized functions of proteins in cotton fiber cells, we developed a label-free liquid chromatography mass spectrometry method for systems-level analyses of fiber proteome. Purified fibers from a single locule were used to fractionate the fiber proteome into apoplast (APOT), membrane-associated (p200), and crude cytosolic (s200) fractions. Subsequently, proteins were identified, and their localizations and potential functions were analyzed using combinations of size exclusion chromatography, statistical and bioinformatic analyses. This method had good coverage of the p200 and APOT fractions, the latter of which was dominated by proteins associated with particulate membrane-enclosed compartments. The apoplastic proteome was diverse, the proteins were not degraded, and some displayed distinct multimerization states compared to their cytosolic pool. This quantitative proteomic pipeline can be used to improve coverage and functional analyses of the cotton fiber proteome as a function of developmental time or differing genotypes.
[学术文献 ] GhMYB102 affects cotton fibre elongation and secondary wall thickening by regulating GhIRX10 in cotton 进入全文
PLANT BIOTECHNOLOGY JOURNAL
Upland cotton (Gossypium hirsutum) is a principal economic crop and a fundamental raw material for the textile industry. The quality of cotton fibres is significantly influenced by the synthesis of cell wall polysaccharides. This study focuses on GhIRX10, a beta-1,4-xylosyltransferase crucial for xylan backbone synthesis. Overexpression of GhIRX10 enhances xylan synthesis, which impacts fibre elongation and secondary cell wall thickening. GhMYB102, identified as a direct regulator of GhIRX10 expression, was confirmed through comprehensive validation. Overexpression of GhMYB102 resulted in a similar phenotype as OE-GhIRX10: increased cell wall thickness and reduced fibre length. Overexpression of GhMYB102 upregulated the expression of key cell wall synthesis-related genes, including GhCESA4/7/8, GhIRXs, GhCESAs, GhGUXs, GhTBLs, GhXTHs, and GhXXTs. Consequently, the cellulose and hemicellulose contents in OE-GhMYB102 lines were significantly increased. GhMYB102 was also validated as a target gene regulated by GhFSN1 and GhMYB7, with the ability to reciprocally regulate GhFSN1 expression. In summary, we propose a regulatory model where GhMYB102 promotes the expression of GhIRX10 and other cell wall-related genes, thereby affecting fibre quality. This study elucidates the regulatory network of secondary cell wall synthesis in cotton and provides potential targets for improving fibre quality through molecular breeding.
[学术文献 ] Cotton2035: From genomics research to optimized breeding 进入全文
MOLECULAR PLANT
Cotton is the world's most important natural fiber crop and serves as an ideal model for studying plant genome evolution, cell differentiation, elongation, and cell wall biosynthesis. The first draft genome assembly for Gossypium raimondii, completed in 2012, marked the beginning of global efforts in studying cotton genomics. Over the past decade, the cotton research community has continued to assemble and refine the genomes for both wild and cultivated Gossypium species. With the accumulation of de novo genome assemblies and resequencing data across virous cotton populations, significant progress has been made in uncovering the genetic basis of key agronomic traits. Achieving the goal of cotton genomics-to-breeding (G2B) will require a deeper understanding of the spatiotemporal regulatory mechanisms involved in genome information storage and expression. We advocate for a cotton ENCODE project to systematically decode the functional elements and regulatory networks within the cotton genome. Technological advances, particularly on single-cell sequencing and high-resolution spatiotemporal omics, will be essential for elucidating these regulatory mechanisms. By integrating multi-omics data, genome editing tools, and artificial intelligence, these efforts will empower the genomics-driven strategies needed for future cotton G2B breeding.
[学术文献 ] Unraveling key genes and pathways involved in Verticillium wilt resistance by integrative GWAS and transcriptomic approaches in Upland cotton 进入全文
FUNCTIONAL & INTEGRATIVE GENOMICS
Verticillium dahliae Kleb, the cause of Verticillium wilt, is a particularly destructive soil-borne vascular disease that affects cotton, resulting in serious decline in fiber quality and causing significant losses in cotton production worldwide. However, the progress in identification of wilt-resistance loci or genes in cotton has been limited, most probably due to the highly complex genetic nature of the trait. Nevertheless, the molecular mechanism behind the Verticillium wilt resistance remains poorly understood. In the present study, we investigated the phenotypic variations in Verticillium tolerance and conducted a genome wide association study (GWAS) among a natural population containing 383 accessions of upland cotton germplasm and performed transcriptomic analysis of cotton genotypes with differential responses to Verticillium wilt. GWAS detected 70 significant SNPs and 116 genes associated with resistance loci in two peak signals on D02 and D11 in E1. The transcriptome analysis identified a total of 2689 and 13289 differentially expressed genes (DEGs) among the Verticillium wilt-tolerant (J46) and wilt-susceptible (J11) genotypes, respectively. The DEGs were predominantly enriched in metabolism, plant hormone signal transduction, phenylpropanoid pathway, MAPK cascade pathway and plant-pathogen interaction pathway in GO and KEGG analyses. The identified DEGs were found to comprise several transcription factor (TF) gene families, primarily including AP2/ERF, ZF, WRKY, NAC and MYB, in addition to pentatricopeptide repeat (PPR) proteins and Resistance (R) genes. Finally, by integrating the two results, 34 candidate genes were found to overlap between GWAS and RNA-seq analyses, associated with Verticillium-wilt resistance, including WRKY, MYB, CYP and RGA. This work contributes to our knowledge of the molecular processes underlying cotton responses to Verticillium wilt, offering crucial insights for additional research into the genes and pathways implicated in these responses and paving the way for developing Verticillium wilt-resistant cotton varieties through accelerated breeding by providing a plethora of candidate genes.
[前沿资讯 ] Promoter editing enables researchers to develop heat-tolerant cotton germplasms in response to global warming 进入全文
SCIENCE CHINA PRESS
Recently, the cotton genetic improvement team at Huazhong Agricultural University successfully developed new heat-resistant cotton lines by precisely editing the promoter region of the key high-temperature-responsive gene GhCKI. This breakthrough provides novel genetic resources and molecular breeding technologies for improving cotton's heat tolerance. In earlier studies, the research team identified GhCKI as a key gene negatively regulating male fertility in cotton under high temperatures. Both overexpression and knockdown of GhCKI resulted in severe male sterility, limiting its application in breeding for heat tolerance. To overcome this limitation, the researchers shifted their focus to promoter editing, aiming to fine-tune the expression level or pattern of GhCKI. Using single-cell ATAC-seq data, they conducted an in-depth analysis of the chromatin accessibility in the promoter region of GhCKI. Combining this with the identification of two critical MYB transcription factor binding sites in the GhCKI promoter responsive to heat stress, the researchers designed 12 sgRNAs. They then applied CRISPR/Cas9 and CRISPR/Cpf1 genome editing technologies to precisely edit and delete specific regions of the GhCKI promoter. Editing analysis revealed that most editing events resulted in large fragment deletions, and the edited plants were categorized into eight major genotypes (GhCKI-pro1 to GhCKI-pro8) based on their promoter modifications. These editing events reduced GhCKI expression levels, and further phenotypic analyses showed that mutants with excessively reduced GhCKI expression exhibited significant male sterility under normal temperatures. However, mutants with moderately reduced expression displayed normal anther development. Under high-temperature stress, two mutants (GhCKI-pro5 and GhCKI-pro6) maintained moderate GhCKI expression levels, showing normal anther development, significantly higher pollen viability, and improved anther dehiscence rates compared to wild-type plants, demonstrating a clear heat-tolerant phenotype. Further investigations into the molecular regulatory mechanisms underlying the heat tolerance of GhCKI-pro5 and GhCKI-pro6 revealed that MYB transcription factors GhMYB73 and GhMYB4 bind to two MYB binding sites in the GhCKI promoter, positively regulating GhCKI expression under heat stress. When the MYB binding sites or their flanking sequences were deleted, the ability of GhMYB73 and GhMYB4 to activate GhCKI expression under high temperatures was hindered. This alteration allowed GhCKI-pro5 and GhCKI-pro6 to maintain normal anther development under extreme heat conditions. This research not only highlights the critical role of the GhCKI gene in breeding heat-tolerant cotton but also lays a solid foundation for developing high-yield, high-quality, and heat-resistant cotton varieties in the future. Moreover, it offers a new strategy for enhancing heat tolerance in other crops by editing promoter regions of key genes, providing technical support to address agricultural challenges posed by global climate change. This breakthrough represents another significant advancement by the Huazhong Agricultural University cotton team in the field of cotton heat tolerance research. In previous studies, the team utilized multi-omics technologies and molecular biology approaches to uncover the mechanisms of heat-induced sterility in cotton and identify heat-tolerant genes, providing theoretical, technical, and resource support for breeding heat-tolerant cotton varieties (Li et al., 2024a, Science China Life Sciences; Li et al., 2024b, Advanced Science; Li et al., 2023, Plant Communications; Khan et al., 2023, Plant Biotechnology Journal; Khan et al., 2023, Crop Journal; Ma et al., 2022, JIPB; Li et al., 2022, Plant Physiology; Ma et al., 2021, New Phytologist; Ma et al., 2018, Plant Cell).
