Abstract
Plant peptide hormones have various important roles in plant development, defense against pathogens, and tolerance to abiotic stress. However, only a limited number of hormone-like peptides have been proven to contribute to salt and drought stress tolerance in plants other than Arabidopsis. In this study, we present the isolation and characterization of MsPROPEP1, a propeptide precursor gene obtained from the legume pasture Medicago sativa. The transcription of the MsPROPEP1 was found to be inducible by NaCl, polyethylene glycol (PEG), and abscisic acid (ABA). The constitutive expression of MsPROPEP1 in alfalfa seedlings mitigated the restriction on plant growth imposed by either salinity or osmotic stress and raised their sensitivity to ABA in promoting stomatal closure. In addition, we synthesized MsPep1 peptide and found that the application of MsPep1 enhanced tolerance to stress induced by NaCl and PEG. In transgenic plants, many ABA-dependent stress-responsive genes are activated; this is known to promote the expression of peroxidase which plays a role in reactive oxygen scavenging. Our findings suggest that MsPROPEP1 is a candidate for the genetic manipulation of salinity and drought tolerance in legume species.