Branched chain amino acids accumulation contributes to drought tolerance in rice

The accumulation of metabolites such as proline as compatible osmolytes is a protective mechanism against drought stress in plants. Similarly, under drought conditions, there is an observable increase in the accumulation of branched-chain amino acids (BCAAs), including the essential amino acids isoleucine, leucine, and valine. Shim et al. investigated rice OsDIAT (DROUGHT-INDUCED BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE), a pivotal enzyme involved in BCAA biosynthesis and the final transamination of BCAAs. RNA-sequencing and gene expression analysis showed that OsDIAT was significantly upregulated under drought conditions. Through CRISPR gene editing, the researchers engineered osdiat mutants, which showed heightened susceptibility to drought and reduced accumulation of BCAAs. Conversely, overexpressing OsDIAT conferred higher plant survival rates and yield under drought conditions. BCAA content in leaves due to the overexpression of OsDIAT was significantly higher under normal condition and further increased upon the exposure to drought when compared with non-transgenic plants. The results suggest that OsDIAT regulates the accumulation of BCAAs in response to drought, which confers drought tolerance in plants. (Summary by Kumanan N Govaichelvan, @NGKumanan) Plant Physiol. 10.1093/plphys/kiac560