The constitutive expression of alfalfa MsMYB2L enhances salinity and drought tolerance of Arabidopsis thaliana.

MYB-type transcription factors are known to participate in the response of plants to a number of stress agents. MsMYB2L is an alfalfa member of this large gene family. Its transcription in alfalfa seedlings was found to be rapidly and strongly induced by salinity, moisture deficiency and exogenously supplied abscisic acid. An analysis based on a yeast one hybrid assay indicated that its product is able to activate transcription, consistent with its function as a transcription factor. When the gene was constitutively expressed in Arabidopsis thaliana, both germination and seedling growth were more sensitive to ABA treatment than wild type, and growth was less strongly compromised by salinity and moisture deficiency stress, presumably as a result of the induction of certain stress-related genes active in ABA-dependent pathways. The transgenic seedlings' enhanced the synthesis of many osmotic regulatory substances such as proline and soluble sugar, and decreased the lipid peroxidation. In all, MsMYB2L represents a potential candidate gene for manipulating the salinity and drought tolerance of alfalfa.