Reaumuria trigyna transcription factor RtWRKY49 confers cold tolerance to Arabidopsis thaliana.

Cold stress can greatly narrow the development and living spaces of plants. As one endangered xerophytic shrub, Reaumuria trigyna can adapt the harsh cold, but the underlying molecular mechanisms remain unknown. Here, the RtWRKY49 gene of Reaumuria trigyna was screened and encoded a nuclear WRKY transcription protein. RtWRKY49 expression mainly located in stem of Reaumuria trigyna, activated by cold, salt and ABA treatments but inhibited by heat and drought treatments. The overexpression of RtWRKY49 remarkably improved cold tolerance in Arabidopsis with the increased growth, chlorophyll content and decreased levels of malondialdehyde, oxygen free radical and hydrogen peroxide. Under cold stress, RtWRKY49 transgenic Arabidopsis had greater antioxidase activities (SOD, POD, CAT, and DHAR), AsA, and proline levels than wild-type plants, with a significant upregulation of AtCAT1, AtPOD, AtDHAR2, and AtP5CS1 genes. Our findings indicated that the RtWRKY49 protein improved the cold tolerance of plants by coordinating the antioxidant and osmoregulation pathways to maintain plant homeostasis under cold stress. In addition to offering the RtWRKY49 as a promising target gene in breeding cold stress resistant crop, our work also provides a basis for the research of Reaumuria trigyna response to cold stress.