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[学术文献 ] Low Phosphorus Stress Decreases Cotton Fiber Strength by Inhibiting Carbohydrate Metabolism 进入全文
JOURNAL OF PLANT GROWTH REGULATION
Insufficient soil-available phosphorus (AP) inhibits photosynthesis and sucrose metabolism in the subtending leaves to cotton bolls, significantly reducing lint yield and fiber length. However, the mechanism by which P deficiency affects cotton fiber strength remains unclear. This study explored the influence of P deficiency on the fiber strength of two cotton varieties, CCRI-79 (low-P tolerant) and SCRC-28 (low-P sensitive). A two-year pool-culture experiment was conducted under three soil AP levels: P0 (3 +/- 0.5), P1 (6 +/- 0.5), and P2 (control, 15 +/- 0.5 mg kg-1). Soil AP deficiency (P1 and P0) decreased the activities of enzymes involved in fiber thickening, including soluble acid invertase (SAI), sucrose synthase (SuSy), sucrose phosphate synthase (SPS), and beta-1,3-glucanase. These reductions led to a 4.0%-16.9% decrease in cellulose content, which was a key substance for fiber strength formation. In addition, the reduced enzymatic activity decreased the maximum velocity of fiber thickening increment (VSmax), ultimately resulting in a 1.0-3.9 cN tex-1 decrease in fiber strength. The beta-1,3-glucan and cellulose levels, as well as SAI and beta-1,3-glucanase activities, showed more pronounced responsiveness to soil AP deficiency in SCRC-28 than in CCRI-79. This indicates that SCRC-28 fibers were more adversely affected under low soil AP levels. Cellulose, SAI, and beta-1,3-glucanase were the key factors affecting fiber strength under low soil AP conditions. This study contributes to a deeper understanding of how soil AP deficiency influences fiber carbohydrate metabolism and fiber strength, offering a scientific basis for breeding low-P tolerant cotton cultivars.
[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.
[学术文献 ] Patterns of phenotypic variation in Gossypium turneri: a wild cotton with a restricted distribution in Sonora, Mexico 进入全文
GENETIC RESOURCES AND CROP EVOLUTION
Crop wild relatives (CWR) represent important genetic resources for crop improvement. Gossypium turneri, a wild cotton species with a restricted distribution in the Sonoran Desert of northwestern Mexico, has been identified as a potential breeding resource for cotton improvement. While several agronomically important traits have been previously identified through limited observations from only one location within its range, phenotypic variation in this xerophytic species has not been thoroughly studied. This study aimed to describe the pattern of phenotypic variation in floral and leaf traits along the three known populations of G. turneri and identify traits of agronomic interest. Leaves and flowers through its distribution range were collected and quantitative and qualitative attributes were analyzed. Phenotypic variation in flowers and leaves was predominantly found among individuals within populations, with a smaller proportion occurring between populations, likely due to the species' restricted distribution. Interpopulation variation in leaf traits was probably influenced by differences in local rainfall, whereas flower traits exhibited minimal interpopulation variation, likely due to similarities in pollinator composition. Some traits of interest for cotton improvement were identified, such as polymorphic bracts and production of anthers without pollen among flowers. This desert-adapted wild cotton offers valuable traits with potential for adaptation of cultivated cotton to water- and heat-stressed environments.
[学术文献 ] GhLPF1 Associated Network Is Involved with Cotton Lint Percentage Regulation Revealed by the Integrative Analysis of Spatial Transcriptome 进入全文
ADVANCED SCIENCE
Cotton fibers, derived from the epidermis of the ovule, provide a sustainable natural fiber source for the textile industry. Traits related to fiber yield are predominantly determined by molecular regulations in the epidermis of the outer integument (OI) region of the cotton ovule. Here, we identify an R2R3 MYB transcription factor coding gene GhLPF1 within the QTL-LP-ChrA06 locus for lint percentage (LP, percentage of lint to seed cotton) through constructing the 1-Day Post Anthesis Cotton Ovule Spatial Transcriptome Atlas. GhLPF1 is subjected as a downstream target of miR828 during fiber development. The direct downstream genes (DDGs) of GhLPF1 are biased to increased expression in GhLPF1-CR, and are preferentially expressed in OI, so that GhLPF1 is primarily a transcriptional repressor to its DDGs. Population-wide transcriptome analysis confirms that expression variation of GhLPF1-DDGs is significantly biased to negative correlation with LP, among which a type I homeobox protein-coding gene GhHB6 is further validated to be the directly downstream gene of GhLPF1. Given these data, it is demonstrated that GhLPF1 mediates a regulation network in LP as a transcriptional repressor, which makes it a valuable functional marker for fiber-trait improvement application from QTL-LP-ChrA06.
[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).
[学术文献 ] Analysis of Mitochondrial Sequence Deletion in the atp9 5′UTR Region and Design of Molecular Markers in Cotton (Gossypium spp.) 进入全文
PLANT BREEDING
Cotton (Gossypium) is the most important fibre crop in the world, consisting of 45 diploid and 7 tetraploid cotton species. These cotton varieties are valuable for breeding, but their molecular identification methods still need further study. We identified an insert/deletion site (AATTT) at the atp9 5 ' UTR region in the mitochondrial genome of cotton, which could be used to distinguish different cotton species. In this study, the target fragments of 33 cotton species (29 diploid and 4 tetraploid species) were amplified by PCR, and the PCR products potentially containing an EcoR I restriction site were subsequently digested and analysed. The sequencing results revealed that 27 out of 33 cotton species lacked 'AATTT' sequences, while six cotton species (G. longicalyx, G. hirsutum, G. barbadense, G. tomentosum, G. mustillinum and G. darwinii) were found to possess the sequences. Additionally, 39 SNPs were found in this region, and specific molecular markers for G. stocksii, G. bickii and E-genome were developed, respectively. The comparative analysis of mitochondrial sequences from diploid and tetraploid cotton species elucidated their genetic diversity and evolutionary relationships, and species-specific markers were able to discriminate among these species, thereby provided a foundation for more targeted use of wild genetic resources in cotton improvement and efforts to ensure their conservation.
