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SUMMARY: Plant height (PH) is an important agronomic trait affecting crop architecture, biomass, resistance to lodging and mechanical harvesting. Elucidating the genetic governance of plant height is crucial because of the global demand for high crop yields. However, during the rapid growth period of plants the PH changes a lot on a daily basis, which makes it difficult to accurately phenotype the trait by hand on a large scale. In this study, an unmanned aerial vehicle (UAV)‐based remote‐sensing phenotyping platform was applied to obtain time‐series PHs of 320 upland cotton accessions in three different field trials. The results showed that the PHs obtained from UAV images were significantly correlated with ground‐based manual measurements, for three trials (R2 = 0.96, 0.95 and 0.96). Two genetic loci on chromosomes A01 and A11 associated with PH were identified by genome‐wide association studies (GWAS). GhUBP15 and GhCUL1 were identified to influence PH in further analysis. We obtained a time series of PH values for three field conditions based on remote sensing with UAV. The key genes identified in this study are of great value for the breeding of ideal plant architecture in cotton. Significance Statement: This study reports the a high‐throughput UAV‐based time series of PH and combines it with a genome‐wide association study to elucidate the genetic basis of plant height in upland cotton. [ABSTRACT FROM AUTHOR]

The increasing water scarcity associated with environmental change brings significant negative impacts to the growth of cotton plants, whereby it is urgent to enhance plant tolerance to drought. Here, we overexpressed the com58276 gene isolated from the desert plant Caragana korshinskii in cotton plants. We obtained three OE plants and demonstrated that com58276 confers drought tolerance in cotton after subjecting transgenic seeds and plants to drought. RNA-seq revealed the mechanisms of the possible anti-stress response, and that the overexpression of com58276 does not affect growth and fiber content in OE cotton plants. The function of com58276 is conserved across species, improving the tolerance of cotton to salt and low temperature, and demonstrating its applicability to improve plant resistance to environmental change. [ABSTRACT FROM AUTHOR]

Protoplasts, which lack cell walls, are ideal research materials for genetic engineering. They are commonly employed in fusion (they can be used for more distant somatic cell fusion to obtain somatic hybrids), genetic transformation, plant regeneration, and other applications. Cotton is grown throughout the world and is the most economically important crop globally. It is therefore critical to study successful extraction and transformation efficiency of cotton protoplasts. In the present study, a cotton callus protoplast extraction method was tested to optimize the ratio of enzymes (cellulase, pectinase, macerozyme R-10, and hemicellulase) used in the procedure. The optimized ratio significantly increased the quantity and activity of protoplasts extracted. We showed that when enzyme concentrations of 1.5% cellulase and 1.5% pectinase, and either 1.5% or 0.5% macerozyme and 0.5% hemicellulase were used, one can obtain increasingly stable protoplasts. We successfully obtained fluorescent protoplasts by transiently expressing fluorescent proteins in the isolated protoplasts. The protoplasts were determined to be suitable for use in further experimental studies. We also studied the influence of plasmid concentration and transformation time on protoplast transformation efficiency. When the plasmid concentration reaches 16 µg and the transformation time is controlled within 12–16 h, the best transformation efficiency can be obtained. In summary, this study presents efficient extraction and transformation techniques for cotton protoplasts. [ABSTRACT FROM AUTHOR]

Summary: Hybrid crop varieties have been repeatedly demonstrated to produce significantly higher yields than their parental lines; however, the low efficiency and high cost of hybrid seed production has limited the broad exploitation of heterosis for cotton production. One option for increasing the yield of hybrid seed is to improve pollination efficiency by insect pollinators. Here, we report the molecular cloning and characterization of a semidominant gene, Beauty Mark (BM), which controls purple spot formation at the base of flower petals in the cultivated tetraploid cotton species Gossypium barbadense. BM encodes an R2R3 MYB113 transcription factor, and we demonstrate that GbBM directly targets the promoter of four flavonoid biosynthesis genes to positively regulate petal spot development. Introgression of a GbBM allele into G. hirsutum by marker‐assisted selection restored petal spot formation, which significantly increased the frequency of honeybee visits in G. hirsutum. Moreover, field tests confirmed that cotton seed yield was significantly improved in a three‐line hybrid production system that incorporated the GbBM allele. Our study thus provides a basis for the potentially broad application of this gene in improving the long‐standing problem of low seed production in elite cotton hybrid lines. [ABSTRACT FROM AUTHOR]

Summary: Improving yield is a primary mission for cotton (Gossypium hirsutum) breeders; development of cultivars with suitable architecture for high planting density (HPDA) can increase yield per unit area.We characterized a natural cotton mutant, AiSheng98 (AS98), which exhibits shorter height, shorter branch length, and more acute branch angle than wild‐type.A copy number variant at the HPDA locus on Chromosome D12 (HPDA‐D12), encoding a dehydration‐responsive element‐binding (DREB) transcription factor, GhDREB1B, strongly affects plant architecture in the AS98 mutant. We found an association between a tandem duplication of a c. 13.5 kb segment in HPDA‐D12 and elevated GhDREB1B expression resulting in the AS98 mutant phenotype. GhDREB1B overexpression confers a significant decrease in plant height and branch length, and reduced branch angle.Our results suggest that fine‐tuning GhDREB1B expression may be a viable engineering strategy for modification of plant architecture favorable to high planting density in cotton. [ABSTRACT FROM AUTHOR]

Cyclic AMP (cAMP) is a pivotal signaling molecule existing in almost all living organisms. It is an intracellular non-protein small molecule that regulates the activity of intracellular enzymes and non-enzyme proteins when its concentration changes in response to the binding of extracellular signals to cell surface receptors. As such, cAMP is referred to as a second messenger with an important role in cell signaling and modulation a variety of cellular responses. cAMP can help plants cope with abiotic stress, but the mechanism by which it improves salt tolerance has not been elucidated. In our study, we treated cotton with Forskolin (a cAMP activator) to increase cAMP levels, and found that it improved cotton seed tolerance to salt stress, thereby improving the germination rate of seeds in saline soil. Through transcriptome analysis, we characterized the responses of ABA, proteins, and pathways to salt stress after cAMP signaling, and four genes related to salt tolerance and signal transduction were identified. Three of them, GhLTI65 , GhGOLS2 , and GhNAC002 were silenced by virus induced gene silencing (VIGs), and the plant tolerance to salt stress was significantly reduced as compared with the control plants. Among these, we found that GhLTI65 (RD29B) was not only involved in the salt stress response, but played a role in the cAMP signaling cascade. We further performed yeast two-hybrid assays and bimolecular fluorescence complementation (BiFC) to determine that GhLTI65 interacts with the SNF1-related protein kinase GhPV42A in the cytoplasm, and that their co-expression is regulated by ABA-related signaling. We propose that ABA and cAMP signaling increase the expression of GhPV42A by integrating related mitogen-activated protein kinase (MAPK)cascade signaling, and that GhPV42A further interacts with GhLTI65 to increase its expression, thereby helping plants to receive signals and to respond to salt stress. [ABSTRACT FROM AUTHOR]

Allotetraploid cotton (Gossypium hirsutum and Gossypium barbadense) are cultivated worldwide for its white fiber. For centuries, conventional breeding approaches increase cotton yield at the cost of extensive erosion of natural genetic variability. Sea Island cotton (G. barbadense) is known for its superior fiber quality, but show poor adaptability as compared to Upland cotton. Here, in this study, we use ethylmethanesulfonate (EMS) as a mutagenic agent to induce genome-wide point mutations to improve the current germplasm resources of Sea Island cotton and develop diverse breeding lines with improved adaptability and excellent economic traits. We determined the optimal EMS experimental procedure suitable for construction of cotton mutant library. At M6 generation, mutant library comprised of lines with distinguished phenotypes of the plant architecture, leaf, flower, boll, and fiber. Genome-wide analysis of SNP distribution and density in yellow leaf mutant reflected the better quality of mutant library. Reduced photosynthetic efficiency and transmission electron microscopy of yellow leaf mutants revealed the effect of induced mutations at physiological and cellular level. Our mutant collection will serve as the valuable resource for basic research on cotton functional genomics, as well as cotton breeding. [ABSTRACT FROM AUTHOR]

This study investigated the identification and distribution of single nucleotide polymorphisms (SNPs) within basic Helix-Loop-Helix (bHLH) transcription factors (TFs) across diverse cotton (Gossypium hirsutum) accessions, including wild, landrace, and improved varieties. Comprehensive genomic analyses revealed substantial SNP diversity in wild cotton, distinct from that observed in landraces and improved accessions. Comparative analysis showed notable variations in SNP abundance and impact levels across different accessions, with missense SNPs being prevalent. Nucleotide substitution patterns highlighted the dominance of G>A and A>G substitutions. Population genetic analyses unveiled significant genetic diversity within wild accessions and distinct clustering between wild and improved accessions. Temporal expression profiling of bHLH genes during cotton fiber development demonstrated dynamic expression patterns, emphasizing their roles in fiber initiation, elongation, and cellulose biosynthesis. Moreover, association analysis identified SNPs significantly associated within bHLH genes, particularly GhbHLH149 , with fiber quality traits, indicating their potential functional significance. Population genetic analyses further revealed evidence of positive selection on GhbHLH149 during cotton improvement. This study provides a comprehensive understanding of SNP diversity, gene expression dynamics, and genetic selection in bHLH genes, offering valuable insights for future cotton breeding efforts aimed at improving fiber quality traits in cotton. [Display omitted] • Uncovering diverse SNP patterns in cotton bHLH TFs. • Revealing distinct SNP impacts across cotton varieties. • Dynamic bHLH gene expression during cotton fiber development. • Significance of GhbHLH149 SNPs for fiber quality traits. • Valuable insights for improving cotton fiber quality through breeding. [ABSTRACT FROM AUTHOR]

• AhCMO -transgenic cotton showed significant resistance to chilling stress and contribute to the improvement of cotton fiber yield. • AhCMO transgenic cotton mainly improved the concentration of cellular osmoprotectants which enhanced chilling resistance in cotton. • AhCMO is an ideal candidate for genetic engineering, which may greatly contribute to enhancing cotton low temperature resistance. Low temperature is a major factor limiting seedling growth and the production of cotton (Gossypium hirsutum L.). However, enhancing chilling tolerance is typically negatively correlated with yield in agricultural production. Here, we demonstrate that transgenic cotton expressing Atriplex hortensis choline monooxygenase (AhCMO) greatly enhanced resistance to chilling stress. The promotion of chilling tolerance is mainly due to an increase in the content of osmoprotectants, especially glycine betaine and proline. The increased chilling tolerance was further verified at the molecular level using genome-wide expression profiling by RNA-sequencing. Further detailed analysis showed that the number of genes involved in scavenging of reactive oxygen species (ROS) was down-regulated and the activity of superoxide dismutase (SOD) and catalase (CAT) were decreased in AhCMO transgenic cotton compared with wild type after low temperture treatment. More importantly, overexpression of AhCMO in cotton moderately improved cotton fiber yield in normal growth condition. These data show that AhCMO transgenic cotton enhances low temperature tolerance via directly accumulating cellular osmoprotectants. Manipulating the expression of AhCMO by biotechnological tools could be a powerful method to enhance chilling tolerance in cotton. [ABSTRACT FROM AUTHOR]

Cotton is not only a raw material for the textile industry, but also an important strategic material. However, traditional breeding methods have narrowed the genetic diversity of current cotton cultivars. Abundant germplasm resources is a solid foundation for breeding, the use of chemical mutagenesis to create abundant mutation is of great significance to cotton breeding. This study used ethyl methanesulfonate (EMS) to mutagenize upland cotton material TM-1. First, we obtained a mutant library with abundant mutations and abundant phenotypes of the leaf, boll, locules numbers and plant architecture,. Second, based on the genome-wide analysis of the leaf and plant structure mutant., it showed that the library had a saturated genome mutations. Further GO and KEGG analysis showed SNPs were significantly enriched in DNA repair and response to hormone, non-homologous end joining (NHEJ) and homologous recombination (HR) pathways, which explained the mutated trait. In addition, we screened candidate gene (Gh_D05G364200) for crumpled leaf by BSA and transcriptome sequencing. Above all, the mutant library we obtained provides abundant resources for cotton functional genomics and breeding. • An upland cotton saturated mutant library was obtained. • SNPs of mutant plants were significantly enriched in DNA repair, NHEJ and HR pathways, which explained the mutated trait. • Gene (Gh_D05G364200) was screened as a candidate gene for crumpled leaf traits. [ABSTRACT FROM AUTHOR]