In the process of growth and development, cotton exhibits premature senescence under various abiotic stresses, impairing yield and fiber quality. NAC (NAM, ATAF1,2, and CUC2) protein widely distributed in land plants, play the critical role in responding to abiotic stress and regulating leaf senescence. We have identified and functional analyzed a NAM domain gene GhNAC82 in upland cotton, it was located on the A11 chromosome 4,921,702 to 4,922,748 bp, only containing one exon. The spatio-temporal expression pattern analysis revealed that it was highly expressed in root, torus, ovule and fiber development stage. The results of qRT-PCR validated that GhNAC82 negatively regulated by salt stress, drought stress, H₂O₂ stress, IAA treatment, and ethylene treatment, positively regulated by the ABA and MeJA treatment. Moreover, heterologous overexpression of GhNAC82 results in leaf premature senescence and delays root system development in Arabidopsis thaliana. The phenotype of delayed-senescence was performed after silencing GhNAC82 by VIGS in premature cotton. Taken together, GhNAC82 was involved in different abiotic stress pathways and play important roles in negatively regulating leaf premature senescence.

F-box/LR (FBXL), Leucine-rich repeats in F-box proteins, belongs to the Skp1-Cullin1-F-box protein (SCF) E3 ligase family. FBXL genes play important roles in plant growth, such as plant hormones, responses to environmental stress, and floral organ development. Here, a total of 518 FBXL genes were identified and analyzed in six plant species. Phylogenetic analysis showed that AtFBXLs, VvFBXLs, and GrFBXLs were clustered into three subfamilies (Ⅰ-Ⅲ). Based on the composition of the F-box domain and carboxyl-terminal amino acid sequence, FBXL proteins were classified into three types (Type-A/-B/-C). Whole-genome duplication (WGD) along with tandem duplications and segmental contributed to the expansion of this gene family. The result indicates that four cotton species are also divided into three subfamilies. FBXLs in cotton were classified into three clades by phylogenetic and structural analyses. Furthermore, expression analyses indicated that the expression patterns of GhFBXLs in different cotton tissues were different. The highly expressed of GH_A07G2363 in 5–8 mm anthers, indicates that this gene might play a role in the reproductive process, providing candidate genes for future studies on cotton fertility materials. This study provides an original functional opinion and a useful interpretation of the FBXL protein family in cotton.

The calmodulin-binding protein 60 (CBP60) family is a gene family unique to plants, and its members play a crucial role in plant defense responses to pathogens and growth and development. Considering that cotton is the primary source of natural cotton textile fiber, the functional study of its CBP60 gene family members is critical. In this research, we successfully identified 162 CBP60 members from the genomes of 21 species. Of these, 72 members were found in four cotton species, divided into four clades. To understand the function of GhCBP60B in cotton in depth, we conducted a detailed analysis of its sequence, structure, cis-acting elements, and expression patterns. Research results show that GhCBP60B is located in the nucleus and plays a crucial role in cotton growth and development and response to salt and drought stress. After using VIGS (virus-induced gene silencing) technology to conduct gene silencing experiments, we found that the plants silenced by GhCBP60B showed dwarf plants and shortened stem nodes, and the expression of related immune genes also changed. In further abiotic stress treatment experiments, we found that GhCBP60B-silenced plants were more sensitive to drought and salt stress, and their POD (peroxidase) activity was also significantly reduced. These results imply the vital role of GhCBP60B in cotton, especially in regulating plant responses to drought and salt stress. This study systematically analyzed CBP60 gene family members through bioinformatics methods and explored in depth the biological function of GhCBP60B in cotton. These research results lay a solid foundation for the future use of the GhCBP60B gene to improve cotton plant type and its drought and salt resistance.

Filamin protein is characterized by an N-terminal actin-binding domain that is followed by 24 Ig (immunoglobulin)-like repeats, which act as hubs for interactions with a variety of proteins. In humans, this family has been found to be involved in cancer cell invasion and metastasis and can be involved in a variety of growth signal transduction processes, but it is less studied in plants. Therefore, in this study, 54 Filamin gene family members from 23 plant species were investigated and divided into two subfamilies: FLMN and GEX2. Subcellular localization showed that most of the Filamin gene family members were located in the cell membrane. A total of 47 Filamin gene pairs were identified, most of which were whole-genome copies. Through the analyses of cis-acting elements, expression patterns and quantitative fluorescence, it was found that GH_ A02G0519 and GH_ D02G0539 are mainly expressed in the reproductive organs of upland cotton, and their interacting proteins are also related to the fertilization process, whereas GH_A02G0216 and GH_D02G0235 were related to stress. Thus, it is speculated that two genes of the GEX2 subfamily (GH_A02G0519 and GH_D02G0539) may be involved in the reproductive development of cotton and may affect the fertilization process of cotton. This study provides a theoretical basis for the further study of the cotton Filamin gene family.