Overexpression of a rice long-chain base kinase gene OsLCBK1 in tobacco improves oxidative stress tolerance

Sphingolipids and their metabolites including long-chain bases (LCBs) and long-chain base 1-phosphates (LCBPs) have been shown to be involved in regulation of various aspects of biological processes in plants. However, little is known about the biological function of LCB kinases (LCBKs), which catalyze the phosphorylation of LCBs to form LCBPs in plant abiotic stress tolerance. In the present study, we performed a functional analysis in transgenic tobacco to explore the possible involvement of a rice LCBK gene OsLCBK1 in abiotic stress tolerance. Root elongation of the transgenic tobacco seedlings with constitutive overexpression of OsLCBK1 was less sensitive to exogenous abscisic acid as compared with the vector-transformed seedlings. The OsLCBK1-overexpressing transgenic tobacco plants showed increased tolerance against oxidative stress after treatment with methyl viologen or H2O2, and up-regulated expression of oxidative stress-related genes. However, the OsLCBK1-overexpressing transgenic tobacco plants showed similar phenotype as vector-transformed plants in response to salt stress and had no change in expression of salt stress-related genes. Our results suggest that OsLCBK1, an enzyme involved in synthesis of LCBPs, may be involved in ABA response and has functions in regulation of oxidative stress tolerance in plants.