Overexpression of Early Light-Induced Protein (ELIP) Gene from Medicago sativa ssp falcata Increases Tolerance to Abiotic Stresses

Medicago sativa subsp. falcata (L.) Arcang. (hereafter falcata) is closely related to alfalfa (Medicago sativa L. ssp. sativa) (hereafter sativa) and shows great tolerance to cold and drought; however, its cold tolerance at molecular or physiological levels has been little investigated. Early light-induced protein (ELIP) is proposed to play a key role in protection of the photosynthetic apparatus from high light stress. In this work, an open reading frame sequence of MfELIP was cloned from falcata. The MfELIP gene exists in a single copy in the genome of falcata. Its expression at the transcript and protein levels was induced by treatments with cold, dehydration, and abscisic acid (ABA); the MfELIP transcript was induced more by cold than by dehydration or ABA. To assess the role of elevated ELIP gene expression in abiotic stress tolerance, transgenic tobacco (Nicotiana tabacum L.) plants overexpressing MfELIP were generated. Compared with the wild type, transgenic plants exhibited a significantly higher survival rate and lower ion leakage after freezing, lower ion leakage and a higher net photosynthetic rate (A) after chilling, a higher plant fresh weight after osmotic stress, and lower ion leakage and higher maximum photochemical efficiency after high light treatment. The results indicated that transgenic plants had increased tolerance to freezing, chilling, osmotic stress, and high light. We suggest that MfELIP confers tolerance to multiple abiotic stresses.