Functional identification of JrMYBs gene in Walnut (Juglans regia) demonstrates it enhances drought stress tolerance

Walnut is a popular nut tree species and often undergoes drought stress. The MYB transcription factor plays a crucial role in a series of plant biological processes and is extensively involved in plant metabolism, growth, and development, as well as biological and abiotic stress. However, there is little information on the response mechanisms of Walnuts to drought stress, resulting in a lack of basic understanding of their drought resistance. In order to explore more functional genes that can respond to stress and enrich the theoretical basis of walnut stress resistance, two MYB transcription factors (JrMYB48 and JrMYB62) were identified and their functions were preliminarily investigated. Bioinformatics analysis showed that JrMYB48 and JrMYB62 are both unstable hydrophobic proteins, and their promoter contain various stress and hormone response elements. qRT-PCR analysis showed that JrMYB48 and JrMYB62 genes could be significantly induced by drought stress. Compared to Wild type (WT), overexpression of JrMYB48 and JrMYB62 not only increased germination rate of Arabidopsis thaliana treated with mannitol, the activity of antioxidant enzymes and the content of osmoregulatory substances under drought stress, but also decreased the water loss rate of Arabidopsis, and also induced the up-regulated expression of drought and ABA-related genes, thus improving the drought tolerance of Arabidopsis, which will provide a theoretical basis for further digging drought response functional genes in walnut.