GhANN1 modulates the salinity tolerance by regulating ABA biosynthesis, ion homeostasis and phenylpropanoid pathway in cotton

Abstract Soil salinity is a major environmental stressor and seriously affects cotton yield and quality. ANNEXINs (ANNs) are a family of calcium-dependent membrane binding proteins, which function in many cellular processes. In this study, we found that GhANN1 (GenBank Accession No: KM062523), encoding an annexin protein in cotton, was strongly upregulated by phytohormone abscisic acid (ABA) and salt stress treatments. Overexpressing GhANN1 improved cotton tolerance to salinity stress, in which GhANN1 regulated ABA and phenylpropanoid biosynthesis pathways and increased the expression of Na+, K+ transporter-related genes in cotton roots. Additionally, transcriptional repressor GhWRKY40-like was involved in ABA-dependent pathway, which could bind directly to the GhANN1 promoter to form a novel GhANN1-ABA-GhWRKY40-like loop and fine-tune cotton response to salt stress. This study reveals the function of GhANN1 in enhancing cotton salt tolerance by regulating ABA accumulation, coordinating ion homeostasis, and participating in phenylpropanoid biosynthesis pathway, which will deepen our insight into plant response to abiotic stresses and provide valuable gene resources for cotton salt-tolerant breeding.