The SDR1-OsDSK2a-EUI1 module orchestrates plant height and multi-stress resilience in rice

Abstract Optimal plant height is critical for yield performance and lodging resistance in rice (Oryza sativa L.). However, genetic resources available for optimizing yield and lodging resistance in breeding programs are currently limited. Here, we report the identification of SEMI-DWARF RICE 1 (SDR1), a semi-dwarf gene encoding a RING-H2 type E3 ubiquitin ligase preferentially expressed in stem internodes. Mechanistically, SDR1 directly targets the key gibberellin (GA)-deactivating enzyme ELONGATED UPPERMOST INTERNODE 1 (EUI1) for degradation via the ubiquitin-proteasome system (UPS), thereby fine-tuning GA homeostasis. Furthermore, SDR1 collaborates with the ubiquitin-like-ubiquitin-associated (UBL-UBA) protein DOMINANT SUPPRESSOR OF KAR 2 (OsDSK2a) for EUI1 turnover. Genetic disruption of SDR1 consequently decreases endogenous GA levels, resulting in semi-dwarfism with enhanced lodging resistance and improved tolerance to salt and disease. Notably, knockout of SDR1 in rice cultivar Zhonghua 11 simultaneously boosts lodging resistance and grain yield under high-density and high-fertility cultivation conditions. Our study thus reveals an SDR1-OsDSK2a-EUI1 module that fine-tunes rice plant architecture and multi-stress resilience via regulation of GA homeostasis, providing a promising target for modern rice breeding.