Effect of salt treatment on theanine biosynthesis in Camellia sinensis seedlings.

Theanine synthetase (TS) is an enzyme involved in theanine biosynthesis in tea plants. Recent studies have revealed that theanine biosynthesis, derived from nitrogen metabolism in tea (Camellia sinensis L.) plants, could be influenced by salt treatment. We have characterized CsTS at the molecular and biochemical level. The expression pattern of CsTS protein was examined by western blot using a self-prepared polyclonal antibody with high specificity and sensitivity. The effect of salt treatment on the levels of theanine synthesis was investigated in this study. Levels of theanine and the total free amino acids were gradually increased in shoots, and reached the maximum on the 8th day after treatment (DAT). The immunoblotting analysis suggested the accumulation of CsTS protein had increased gently up to 8 DAT, and subsequently declined, both in roots and shoots, which is one of the main evidences that resulted in the variation of theanine concentration under salt treatment. Together, these data revealed that theanine synthesis takes place both in root and shoot and CsTS accumulation is positively affected by salt treatment.