The OsPUB33-OsNAC120 module acts as a molecular switch between the drought stress response and growth recovery in rice

Recurrent drought stress seriously threatens plant growth and crop production, but plant drought adaptation often comes at a yield penalty, known as the growth-defense trade-off. Therefore, deciphering the mechanisms of trade-off between plant growth and drought tolerance is of great importance for plant survival and crop yield in fluctuating environments. Our recent studies have shown that U-box E3 ubiquitin ligase OsPUB33 reduces rice (Oryza sativa L.) grain yield via ubiquitination and degradation of the transcription factor OsNAC120, a positive regulator of grain size, whereas OsNAC120 compromises rice drought tolerance through transcriptionally repressing drought-responsive genes. In the present study, we found that the OsPUB33-OsNAC120 module acts as a molecular switch between drought response and growth recovery in rice. OsPUB33 enhanced ABA-induced drought tolerance, and its protein abundance rapidly increased at the early stage of drought stress and returned to normal at the rehydration stage, whereas OsNAC120 acted oppositely. Genetic evidence showed that OsPUB33 and OsNAC120 regulate rice drought response through a common pathway. Notably, OsNAC120 phosphorylation mediated by OsSAPK9, a key SnRK2 kinase in ABA signaling, enhanced its interaction with OsPUB33, thus promoting OsNAC120 ubiquitination for degradation under drought stress and increasing rice drought tolerance. When drought stress was relieved, OsPUB33 abundance declined, while OsNAC120 levels increased, consequently achieving growth recovery. These findings indicate that the OsPUB33-OsNAC120 module, which is controlled by OsSAPK9, is a molecular switch between the drought response and growth recovery, revealing a key mechanism of plant growth regulation under drought stress in rice.