Analysis of the Function of the Alfalfa Mslea-D34 Gene in Abiotic Stress Responses and Flowering Time.

A novel late embryogenesis abundant (LEA) gene, MsLEA-D34, was cloned from alfalfa (Medicago sativa L.). Its function and gene regulatory pathways were studied via overexpression (OE) and RNA interference (RNAi) of the gene in Arabidopsis and in hairy roots of alfalfa, as well as via analyzing key genes related to MsLEA-D34 during developmental phases in alfalfa. The results showed that MsLEA-D34 was a typical intrinsically disordered protein with a high capability for protein protection. Overexpression of MsLEA-D34 increased plant tolerance to osmotic and salt stresses, and caused Arabidopsis early flowering under drought and well-watered conditions. Overexpressing MsLEA-D34 induced up-regulation of FLOWERING LOCUS T (FT) and GIGANTEA (GI) at the flowering phase of Arabidopsis and hairy roots of alfalfa, but only FT was down-regulated in MsLEA-D34-RNAi lines. A positive effect of MsLEA-D34 on FT accumulation was demonstrated in alfalfa hairy roots. An ABA-responsive element (ABRE)-binding transcription factor (MsABF2), a novel transcription factor cloned from alfalfa, directly bound to the RY element in the MsLEA-D34 promoter and activated MsLEA-D34 expression. The above results indicate that MsLEA-D34 can regulate abiotic stress response in plants and influence flowering time of Arabidopsis.