Overexpression of OsLea14-A improves the tolerance of rice and increases Hg accumulation under diverse stresses

The group 5 LEA (late embryogenesis abundant) proteins are an atypical LEA protein group, which is associated with resistance to multiple stresses. In this study, OsLea14-A gene was isolated from Oryza sativa L., which encodes a 5C LEA protein with 151 amino acids. The qPCR analysis showed that OsLea14-A expressed in all tissues and organs at all times. The expression of OsLea14-A in the panicles of plumping stage were dramatically increased. The heterologous expression of OsLea14-A in Escherichia coli improved its growth performance under salinity, desiccation, high temperature, and freeze-thaw stresses. The purified OsLea14-A protein can protect LDH activity from freeze-thaw-, heat-, and desiccation-induced inactivation. The overexpression of OsLea14-A in rice improved tolerance to dehydration, high salinity, CuSO4, and HgCl2, but excluding K2Cr2O7. The analysis of metal contents showed that the accumulation of OsLea14-A protein in transgenic rice could increase the accumulation of Hg, but could not increase the accumulation of Na, Cr, and Cu after HgCl2, NaCl, K2Cr2O7, and CuSO4 treatment, respectively. These results suggested that OsLea14-A conferred multiple stress tolerance and Hg accumulation, which made it a possible gene in genetic improvement for plants to acclimatize itself to multiple stresses and remediate Hg-contaminated soil.