シキミ酸経路におけるDAHPS2の発現を改善するためのプライム編集により、タイプBサイトカイニン応答調節因子RR26がイネの湛水耐性を向上させる

Early postgermination growth is critical for uniform seedling emergence in direct-seeded rice, yet its regulatory mechanism remains unclear. Here, we identified DS1, encoding the shikimate pathway initial enzyme DAHPS2, from a dwarf and sterile mutant (ds1) in Huazhan (HZ). Loss of DS1 disrupted the shikimate pathway, thereby reducing indole-3-acetic acid (IAA) levels via the downstream tryptophan-dependent IAA biosynthesis pathway and inducing excessive jasmonic acid (JA) production, resulting in severely inhibited postgermination growth. Exogenous auxin analog NAA or the JA biosynthesis inhibitor DIECA partially rescued the mutant phenotype. Conversely, DS1 overexpression elevated IAA levels, reduced JA accumulation, and enhanced postgermination growth, thereby facilitating rapid seedling emergence in rice under submergence. This result was subsequently confirmed in the Zhongjia3 (ZJ3) cultivar. We further demonstrated that DS1 is transcriptionally activated by RR26, a type-B cytokinin response regulator, through binding to the DS1-7 cis-element. Using prime editing, we precisely modified DS1-7 in HZ, generating transgene-free germplasm with improved DS1 expression and enhanced submergence tolerance. Our findings establish an RR26-DS1 module that regulates IAA-JA homeostasis through the shikimate pathway, providing mechanistic insights into postgermination growth and valuable germplasm for breeding direct-seeded rice.