Abstract
BACKGROUND: Salt and drought are the primary environmental stress factors that severely threaten plant growth, development, and yield. bZIP transcription factors reportedly play crucial roles in plant responses to both biotic and abiotic stressors. However, the biological function of bZIP transcription factors in oil crops, particularly walnuts, under salt and drought stress remains unclear. RESULTS: In this study, members of the walnut bZIP gene family were identified based on the walnut genome Chandler 2.0. Transcriptome data and RT-qPCR results were used to analyze the expression patterns of various JrbZIP genes under biotic and abiotic stress, revealing that JrbZIP40 was strongly induced by both drought and salt stress. Subcellular localization and transcriptional activation assays demonstrated that JrbZIP40 localized to the nucleus and exhibited transcriptional activation activity. Overexpression of JrbZIP40 in transgenic Arabidopsis seedlings significantly enhanced resistance to salt and drought stress. DAP-seq and Dual-luciferase results indicated that JrbZIP40 may bind to the JrHB7 and JrATG8G promoters and activate their expression, contributing to stress resistance. CONCLUSIONS: Overall, this study elucidates the regulatory network and biological functions of JrbZIP40 in drought and salt tolerance, providing a theoretical foundation and candidate gene resources for the future use of genetic engineering to improve walnut stress resistance.