The lncRNA-encoded micropeptide ANCHOR promotes lateral root growth and drought tolerance in rice

Lateral roots (LRs) are important components of plant root systems, determining the robustness of root system architecture and influencing water uptake efficiency. Enhancing the phenotypic plasticity of LRs is key to improving crop production under fluctuating environmental conditions. In this study, we identified ANCHOR, a micropeptide encoded by a long noncoding RNA that is predominantly expressed in LR primordia and plumules. Overexpression of ANCHOR resulted in significantly longer and wider LRs, thereby altering root system architecture and enhancing drought tolerance; knockouts of ANCHOR produced the opposite phenotypes. Mechanistically, ANCHOR localized to plastids and directly interacted with the lysine biosynthetic enzyme LL-diaminopimelate aminotransferase 1 (LL-DAPAT). Our results indicate that ANCHOR functions as a "molecular glue" that enhances DAPAT dimerization. Through its influence on lysine metabolism, ANCHOR raises the levels of the auxin biosynthetic precursor tryptophan, thereby affecting auxin homeostasis. These findings show that lncRNA-derived micropeptides, like their precursor RNAs, can function as fine-tuning regulators. This function of micropeptides, together with their small molecular size, may make them suitable for application as bioeffectors to stimulate root growth and improve plant tolerance to abiotic stress without side effects for plants.