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

Abstract

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.

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