GhWRKY41 Confers Salt Tolerance by Enhancing Photosynthetic Capacity in Cotton (Gossypium hirsutum).

Abstract

Cotton is a vital textile resource; however, its productivity and fibre quality are severely affected by soil salinity. Identifying salt-tolerant genes is critical for improving cotton resilience, yet the molecular mechanisms linking photosynthesis and chlorophyll metabolism to the salt stress response remain poorly understood. In this study, the WRKY transcription factor GhWRKY41 was identified as a key regulator of salt tolerance by screening WRKY family members responsive to salinity stress. Functional validation demonstrated that GhWRKY41 overexpression significantly enhanced salt tolerance in cotton and Arabidopsis, whereas gene knockdown increased the sensitivity of cotton to salt stress. GhWRKY41 directly binds to and activates the expression of two salt-responsive genes, GhMPK3 and GhLEA3. Global transcriptomic analyses revealed that GhWRKY41 and its Arabidopsis homologues regulate a set of genes involved in photosynthesis and salt stress responses. Notably, GhWRKY41 knockdown downregulated genes encoding photosystem reaction centre proteins, impairing photosynthetic capacity under salt stress. These findings indicate that GhWRKY41 enhances salt tolerance primarily by maintaining elevated photosynthetic activity in cotton under saline conditions. This study provides novel insights into the complex regulatory network underlying the response of cotton to salt stress and presents a valuable genetic resource for breeding salt-tolerant cotton varieties.