Auxin response factor OsARF22 controls rice seed vigor by suppressing ABA signaling

Seed vigor is a critical agronomic trait in rice (Oryza sativa L.) cultivation, determining rapid and uniform germination and seedling establishment. Although numerous auxin response factors (OsARFs) regulate various important traits in rice, their functions regarding seed vigor remain unclear. Here, we demonstrate that OsARF22 functions as a predominant positive regulator of seed vigor. Loss of OsARF22 resulted in reduced seed germination and impaired seedling establishment, whereas overexpression of OsARF22 enhanced seed vigor. OsARF10, a homolog of OsARF22, played a partially redundant but minor role. Transcriptomic analysis revealed that OsABI5 is preferentially associated with OsARF22, and that the OsARF22-OsABI5 module co-regulates a set of ABA-responsive genes. Mechanistically, OsARF22 directly interacts with OsABI5 and promotes its proteasomal degradation, thereby suppressing ABA signaling. In Osarf22 mutants, impaired OsABI5 degradation, together with ABA accumulation and enhanced OsABI5 transcription, leads to OsABI5 hyperaccumulation and suppression of seed vigor. Our findings uncover a regulatory module in which OsARF22 acts as a post-translational repressor of ABA signaling to promote seed vigor, and highlight OsARF22 as a potential target for breeding rice varieties with high seed vigor. This work provides insights into the functional diversification of orthologous transcription factors across species.