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Ubiquitin‐conjugating enzyme (UBC) is a crucial component of the ubiquitin‐proteasome system, which contributes to plant growth and development. While some UBCs have been identified as potential regulators of abiotic stress responses, the underlying mechanisms of this regulation remain poorly understood. Here, we report a cotton (Gossypium hirsutum) UBC gene, GhUBC10‐2, which negatively regulates the salt stress response. We found that the gain of function of GhUBC10‐2 in both Arabidopsis (Arabidopsis thaliana) and cotton leads to reduced salinity tolerance. Additionally, GhUBC10‐2 interacts with glutathione S‐transferase (GST) U17 (GhGSTU17), forming a heterodimeric complex that promotes GhGSTU17 degradation. Intriguingly, GhUBC10‐2 can be self‐polyubiquitinated, suggesting that it possesses E3‐independent activity. Our findings provide new insights into the PTM of plant GST‐mediated salt response pathways. Furthermore, we found that the WRKY transcription factor GhWRKY13 binds to the GhUBC10‐2 promoter and suppresses its expression under salt conditions. Collectively, our study unveils a regulatory module encompassing GhWRKY13–GhUBC10‐2–GhGSTU17, which orchestrates the modulation of reactive oxygen species homeostasis to enhance salt tolerance. Summary statement: GhUBC10‐2 negatively regulates salt tolerance by targeting glutathione S‐transferase U17 (GhGSTU17) for its degradation. GhWRKY13 binds the W‐box of the GhUBC10‐2 promoter to repress GhUBC10‐2 transcription. The GhWRKY13–GhUBC10‐2–GhGSTU17 module offers a guidance for cotton breeding. [ABSTRACT FROM AUTHOR]

Background: Cotton fiber is a model tissue for studying microtubule-associated proteins (MAPs). The Xklp2 (TPX2) proteins that belong to the novel MAPs member mainly participate in the formation and development of microtubule (MT). However, there is a lack of studies concerning the systematic characterization of the TPX2 genes family in cotton. Therefore, the identification and portrayal of G. hirsutum TPX2 genes can provide key targets for molecular manipulation in the breeding of cotton fiber improvement. Result: In this study, TPX2 family genes were classified into two distinct subclasses TPXLs and MAP genes WAVE DAMPENED2-LIKE (WDLs) and quite conservative in quantity. GhWDL3 was significantly up-regulated in 15 days post anthesis fibers of ZRI-015 (an upland cotton with longer and stronger fiber). GhWDL3 promotes all stem hairs to become straight when overexpressed in Arabidopsis, which may indirectly regulate cotton fiber cell morphology during fiber development. Virus induced gene silencing (VIGS) results showed that GhWDL3 inhibited fiber cell elongation at fiber development periods through regulating the expression of cell wall related genes. Conclusion: These results reveal that GhWDL3 regulated cotton fiber cell elongation and provide crucial information for the further investigation in the regulatory mechanisms/networks of cotton fiber length. [ABSTRACT FROM AUTHOR]

Plants are frequently subjected to a range of environmental stresses, including drought, salinity, cold, pathogens, and herbivore attacks. To survive in such conditions, plants have evolved a novel adaptive mechanism known as 'stress memory'. The formation of stress memories necessitates coordinated responses at the cellular, genetic/genomic, and epigenetic levels, involving altered physiological responses, gene activation, hyper-induction and chromatin modification. Cotton (Gossypium spp.) is an important economic crop with numerous applications and high economic value. In this study, we establish G. hirsutum drought memory following cycles of mild drought and re-watering treatments and analyzed memory gene expression patterns. Our findings reveal the physiological, biochemical, and molecular mechanisms underlying drought stress memory formation in G. hirsutum. Specifically, H3K4me3, a histone modification, plays a crucial role in regulating [+ /+ ] transcriptional memory. Moreover, we investigated the intergenerational inheritance of drought stress memory in G. hirsutum. Collectively, our data provides theoretical guidance for cotton breeding. • We ensured that cotton drought memory was established after cycles of mild drought and re-watering treatment. In the process of repeated drought, the antioxidant capacity of seedlings was significantly enhanced. • H3K4me3 modification was involved in the formation of [+ /+ ] transcriptional memory, which only maintained 4 days. • The drought environment of the parents enhanced the ability of the progenies to resist adversity. However, the prolonged drought-induced H3K4me3 was not transmitted to the progenies, suggesting that different molecular mechanisms are involved in short- and long-term memory. [ABSTRACT FROM AUTHOR]