GhBZR15 improved the tolerance of cotton to cold and salt stress revealed by genome-wide characterization of BZR genes family

Brassinazole resistant (BZR) transcription factors play important roles in brassinosteroids (BRs) signaling pathway of plants, which are involved in many developmental processes and the responses to abiotic stress by regulating the expression of related genes. In order to explore the molecular mechanism of BZR transcription factors in cotton in response to abiotic stress, the BZR transcription factors in four cotton genomes were identified and analyzed. A total of 67 BZR transcription factors were identified and divided into three subfamilies according to their genetic relationship. The expression levels of BZR under cold, heat, salt, and drought treatments were analyzed to predict their function under abiotic stress. Promoter analysis of BZR proteins showed that light signaling can enhance the BZR transcriptional activity. The subcellular localization experiment showed that GhBZR15 protein was mainly distributed in the nucleus. Arabidopsis thaliana L. overexpressing GhBZR15 gene showed stronger cold tolerance and salt tolerance than wild type. These results, combined with the GhBZR protein-interaction network, suggest that the interaction of GhBZR with phytochrome interacting factors (PIF4) plays an important role in abiotic stress responses. These findings provide a basis for further understanding the function of BZR in cotton.