BrERF109 positively regulates the tolerances of drought and salt stress in Chinese cabbage

Ethylene response factors (ERFs) are plant-specific transcription factors and play essential roles in plants ' defense responses to abiotic stresses. In this study, we identified an ethylene response factor BrERF109, and explored its roles in response to drought and salt stress. The BrERF109 protein contained an AP2 domain and was localized in the nucleus. Expression analysis suggested that BrERF109 was mainly expressed in root and leaf, and highly induced by drought, salt, heat, and cold stresses. Ectopic expression of BrERF109 in Arabidopsis improved the tolerance to drought and salt stress in transgenic plants, accompanied by reduced ABA sensitivity, enhanced antioxidant enzyme activities and chlorophyll content, as well as induced the expression of canonical stress responsive genes. Silencing of BrERF109 in Chinese cabbage by virus-induced gene silencing (VIGS) led to plants ' susceptibility to drought and salt stress, and suppressed superoxide dismutase and peroxidase activities. Furthermore, BrLTP3 , BrCIPK6 , BrAZF2 , and BrZAT10 genes containing GCC-box in their promoter regions were identified as downstream candidate targets of BrERF109. Overall, our study demonstrated that BrERF109 is a key positive regulator in response to drought and salt stress in Chinese cabbage, and serves as a valuable target gene for breeding new cultivars with enhanced tolerances to abiotic stresses in Brassica vegetables.