OsR126 IncRNA integrates AtWRKY46 and AtEM1 into ABA signaling in Arabidopsis.

Key message: Pol III-dependent rice OsR126 lncRNA affects the salt tolerance of Arabidopsis by regulating OsR126/AtWRKY46/AtEM1 module, this discovery further elucidates the ncRNA-mediated molecular regulatory network of plant salt stress. Rice is an important food crop that is frequently affected by various abiotic stresses during growth. In particular, salt stress leads to ion toxicity and oxidation, severely restricting rice yield and quality. Abscisic acid (ABA) is an important anti-stress hormone in plants. Stress can lead to ABA accumulation and signaling that mediates plant stress adaptation in various ways. However, there are many unsolved mysteries regarding the mechanism of ABA action related to stress. Stress-related long non-coding RNAs (lncRNAs) transcribed by RNA polymerase II (Pol II) play crucial roles in stress response by influencing flanking gene expression, epigenetic regulation, endogenous antisense mechanisms, and other aspects in plants. This study discovered that OsR126 lncRNA responded to salt and ABA in rice, and the OsR126 lncRNA overexpression significantly reduced the tolerance of germinating seeds and root growth to saline stress in an ABA-dependent manner in Arabidopsis. In OsR126-AtOXs, AtEM1 expression significantly increased, while AtWRKY46 expression was inhibited under ABA. Seed germination and root growth of AtEM1-OXs and wrky46 showed strong ABA sensitivity. Meanwhile, AtWRKY46 directly bound to the W-box in the AtEM1 promoter and inhibited its expression. This suggests that OsR126 lncRNA affects the salt tolerance of Arabidopsis by integrating AtWRKY46 into ABA signaling to mediate AtEM1 transcription. Discovery of the OsR126/AtWRKY46/AtEM1 regulatory module helps to further elucidate the non-coding RNA (ncRNA)-mediated molecular regulatory network of plant salt stress, provides a new gene resource to breed stress-resistant varieties, and has important agricultural application value.