Maize ZmRAV1 contributes to salt and osmotic stress tolerance in transgenic arabidopsis

RAV1 (Related to ABI3/VP1) has been widely studied in plants such as Arabidopsis, pepper and rice; however, the functions of RAVs in maize have not been described. In this study, a novel gene ZmRAV1 was amplified from a Zea mays inbred line H21. This gene was predicted to encode a transcription factor with 2 distinct DNA-binding domains, AP2 and B3, which are both present in members of the RAV family. Transient expression assays of a 35S::YFP-ZmRAV1 fusion construct in onion epidermal cells revealed that the ZmRAV1 protein is localized in the nucleus. ZmRAV1 expression was upregulated in maize by dehydration, salt, and ABA stress. Overexpression of ZmRAV1 in transgenic Arabidopsis plants enhanced salt and osmotic stress tolerance compared to the wild type, further confirmed by increased survival rate, longer primary roots and physiological characteristics such as lower relative electrolyte leakages. Illumina sequencing revealed that a number of salt responsive genes, primarily involved in reactive oxygen species scavenging, were upregulated in the ZmRAV1 transgenic line compared to the wild-type plants. The detection of the activity of antioxidant enzyme in WT and 35S::ZmRAV1 plants under salt stress shown that, higher maintenance of POD contributes to the salt tolerance of Arabidopsis transgenic lines. These data suggest that ZmRAV1 functions as a transcriptional activator that may be involved in the salt and osmotic resistance signaling pathways in plants.