Cotton (Gossypium hirsutum L.), the most important textile crop worldwide, often encounters abiotic stress during its growing season and its productivity is significantly limited by adverse factors. Trihelix transcription factors (also known as GT factors) are important proteins involved in the morphological development and responses to abiotic stress in plants. However, their functions and molecular mechanisms in the cotton toward abiotic stress response remain unclear. In this study, a member (GhGT26) of the cotton Trihelix family was functionally characterized in the model plant Arabidopsis. This protein containing a SANT domain belongs to the GT-1 subgroup of trihelix proteins. GhGT26 was widely expressed in tissues (with the highest level in flower) and responded to high salt and ABA treatments at the transcriptional level. Using the Arabidopsis protoplast assay system, we found that the GhGT26 protein was located in the cell nuclei. The EMSA assay revealed that the GhGT26 protein could bind to the Site1-type GT cis elements (GT-3a) and MYB elements MRE3 and MRE4. The overexpression of GhGT26 improved plant tolerance to salt stress in transgenic Arabidopsis plants. Although ABA inhibits root elongation, the statistical analysis revealed that the root lengths of GhGT26-overexpressing Arabidopsis were the same as the wild plants after ABA treatment. Our results demonstrate that GhGT26 positively regulates salt stress via ABA-independent pathways. This evidence suggests that the GhGT26 may participate in the regulation of stress tolerance in cotton.

Background: The B3-domain transcription factor ABI3 (ABSCISIC ACID INSENSITIVE 3) is a critical regulator of seed maturation, stress adaptation, and hormonal signaling in plants. However, its evolutionary dynamics and functional roles in cotton (Gossypium spp.) remain poorly characterized. Methods: We conducted a comprehensive genome-wide investigation of the ABI3 gene family across 26 plant species, with a focus on 8 Gossypium species. Analyses included phylogenetics, chromosomal localization, synteny assessment, gene duplication patterns, protein domain characterization, promoter cis-regulatory element identification, and tissue-specific/spatiotemporal expression profiling under different organizations of Gossypium hirsutum. Results: Phylogenetic and chromosomal analyses revealed conserved ABI3 evolutionary patterns between monocots and dicots, alongside lineage-specific expansion events within Gossypium spp. Syntenic relationships and duplication analysis in G. hirsutum (upland cotton) indicated retention of ancestral synteny blocks and functional diversification driven predominantly by segmental duplication. Structural characterization confirmed the presence of conserved B3 domains in all G. hirsutum ABI3 homologs. Promoter analysis identified key stress-responsive cis-elements, including ABA-responsive (ABRE), drought-responsive (MYB), and low-temperature-responsive (LTRE) motifs, suggesting a role in abiotic stress regulation. Expression profiling demonstrated significant tissue-specific transcriptional activity across roots, stems, leaves, and fiber developmental stages. Conclusions: This study addresses a significant knowledge gap by elucidating the evolution, structure, and stress-responsive expression profiles of the ABI3 gene family in cotton. It establishes a foundational framework for future functional validation and targeted genetic engineering strategies aimed at developing stress-resilient cotton cultivars with enhanced fiber quality.

Background: Genetic diversity and genetic differentiation between Gossypium hirsutum-Gossypium barbadense introgression lines (ILs) and early-maturing upland cotton lines are critical for resolving the core breeding contradiction in Xinjiang cotton region: narrow genetic basis of early-maturing cultivars and late maturity of ILs with superior fiber quality. Xinjiang is one of the major cotton-producing regions in China, and breeding high-quality early-maturing upland cotton adapted to local ecological conditions is essential for improving cotton yield and quality. However, the genetic relationship and differentiation between the two types of cotton germplasm remain unclear, which hinders the efficient utilization of germplasm resources in breeding. Therefore, this study aimed to clarify the genetic diversity and differentiation between the two germplasm types and identify key candidate loci related to early maturity and fiber quality, providing support for cotton breeding. Results: Here, we used a 40K Single Nucleotide Polymorphism chip to genotype core cotton germplasm in northern Xinjiang, and analyzed their population structure, genetic diversity and functional SNP loci associated with early maturity and fiber quality. The tested materials were clearly divided into two subgroups (ILs and early-maturing lines). Genetic diversity analysis revealed a significantly narrow genetic basis in the early-maturing subgroup, while the IL subgroup had higher genetic diversity. Specifically, the early-maturing subgroup showed lower nucleotide diversity and polymorphism information content compared with the IL subgroup, indicating that the genetic variation of early-maturing cotton germplasm in northern Xinjiang is relatively limited. A total of 25 non-synonymous SNPs were identified, among which the c.A613G:p.T205A mutation in GH_D09G1484 (mRNA-decapping enzyme 1, DCP1) was a characteristic variation of early-maturing cotton, and a possible non-synonymous mutation in GH_A09G2400 (Heat shock transcription factor A6b, HSFA6B) was associated with fiber development. These two candidate genes were annotated to be involved in plant growth and development, further supporting their potential roles in regulating cotton early maturity and fiber quality. Conclusions: This study clarified the genetic differentiation between the two types of germplasms and identified key candidate loci for early maturity and fiber quality, providing precise molecular markers and theoretical support for breeding high-quality early-maturing upland cotton adapted to Xinjiang’s ecological conditions. The results also highlight the value of Gossypium hirsutum–Gossypium barbadense introgression lines in enriching the genetic basis of early-maturing cotton, which can be further utilized to solve the core breeding contradiction in the Xinjiang cotton region.

Cotton is a globally significant cash crop; however, its production is frequently compromised by aphid infestations. This study systematically investigated

Drought is one of the most severe and frequently occurring abiotic stresses that significantly threaten cotton production. In this study, to identify key genes associated with drought resistance in upland cotton, BSA-seq was integrated with RNA-seq (R) and proteomic (P) approaches conducted on an F₂ population and two parental accessions exhibiting extreme drought resistance: the drought-sensitive accession “2406211” (A) and the drought-resistant accession “2403739” (B). After crossing the two parent plants, the F₂ generation from these accessions was used to construct pools representing the two extreme drought resistance traits. BSA-seq analysis identified five QTL regions on chromosomes A02 (9.10 Mb–11.10 Mb), A07 (18.20 Mb–20.70 Mb), A09 (39.80 Mb–42.40 Mb), D03 (8.90 Mb–13.80 Mb), and D04 (10.80 Mb–13.40 Mb). RNA-Seq analysis revealed a total of 5844 differentially expressed genes (DEGs) in RAW1 (W1, control condition) versus RAW2 (W2, drought stress), comprising 2499 up-regulated and 3345 down-regulated genes. In RBW1 versus RBW2, 6586 DEGs were detected, with 3286 up-regulated and 3300 down-regulated genes. Proteomic analysis identified 1352 differentially expressed proteins (DEPs) in PAW1 versus PAW2, including 453 up-regulated and 899 down-regulated proteins, and 3440 DEPs in PBW1 versus PBW2, with 1773 up-regulated and 1667 down-regulated proteins. By integrating transcriptomic and proteomic data to analyze genes located within the BSA target regions, we identified 5 DEGs/DEPs, including GH_D04G0687, GH_A02G0703, GH_A07G1211, GH_A07G1202, and GH_D04G0702, as potential candidate genes within the drought-resistance target intervals. This study expands transcriptomic and proteomic resources and identifies novel gene targets for the genetic improvement and breeding of cotton cultivars.