A tRNA-Arg-Derived Fragment Mediates Gene Silencing of the Development-Related OsIIP5 in Rice Under Oxidative Stress

Stress leads to reactive oxygen species (ROS) generation in plants, which causes oxidative stress and DNA damage. Studies have demonstrated that oxidative stress leads to rapid increases in tRNA degradation. However, the function of tRNA-derived small RNAs (tsRNA) in plants under oxidative stress has seldom been evaluated. This study investigated the short tsRNAs called tRNA fragments (tRFs) in rice roots treated with hydrogen peroxide (H₂O₂). Small RNA sequencing and RT-qPCR revealed the rapid increases in the expression levels of tRF-ArgTCG-5, comprising 19 nt, in rice seedling under H₂O₂ treatment. Degradome sequencing data indicated that tRF-ArgTCG-5 bound to the 3' untranslated region of the OsIIP5 transcript and cleaved it at the noncanonical sites. Agrobacterium transient assay in tobacco leaves demonstrated that tRF-ArgTCG-5 inhibited the expression of GFP fused to the tRF-ArgTCG-5 binding site of OsIIP5, revealing a post-transcriptional regulatory relationship between tRF-ArgTCG-5 and OsIIP5. ABA treatment and nitrogen deficiency played roles in the regulation of OsIIP5 expression. In addition, rice seedlings with a mutation in OsIIP5 exhibited low spikelet fertility. Conclusively, H₂O₂ treatment led to the rapid accumulation of tRF-ArgTCG-5 in rice plants, and the accumulated tRF-ArgTCG-5 inhibited the expression of its target OsIIP5. OsIIP5 may contribute to rice grain yield.