Functional identification of a rice trehalase gene involved in salt stress tolerance

Trehalose is a disaccharide with a pivotal role in plant growth and development. In contrast to the recent advances in understanding trehalose biosynthesis in plants, their catabolism of trehalose is poorly understood. Here, we isolated and characterized a trehalase gene, OsTRE1, in rice (Oryza sativa L.). An expression analysis in young seedlings revealed that OsTRE1 is induced by stresses such as salt, drought, and chilling. ABA treatment also transiently upregulated OsTRE1 expression. The accumulation of OsTRE1 mRNA in response to 150 mM NaCl was consistent with an increased trehalase activity in the roots. Transgenic rice plants overexpressing OsTRE1 showed remarkable increases in trehalase activity and dramatic decreases in trehalose abundance compared with the wild type, with little change in the levels of other soluble sugars, such as glucose, fructose, and sucrose. Callus cells generated from the transgenic lines overexpressing OsTRE1 were able to grow using trehalose as their sole carbon source. These data indicated that OsTRE1 is a functional trehalase gene in rice. The OsTRE1 overexpressors did not have notable morphological alterations or growth defects but exhibited enhanced salt tolerance, suggesting the involvement of OsTRE1 in salt stress tolerance in rice.