Identification of multiple miRNA-encoded peptide reveals OsmiPEP162a putatively stabilizes OsMIR162 in rice

MiPEPs regulate growth, development and stress response. Identification of rice miPEPs plays a crucial role in elucidation of molecular functions of rice miPEPs and rice genetic improvement. MicroRNAs (miRNAs) are derivatives of primary miRNAs (pri-miRNAs) and govern the expression of target genes. Plant pri-miRNAs encode regulatory peptides known as miPEPs, which specifically boost the transcription of their originating pri-miRNA. Although there are hundreds of pri-miRNAs in rice, research on whether they encode functional peptides is limited. In this study, we identified 10 miPEPs using a transient protoplast expression system. Among these, we focused our attention on OsmiPEP162a, which influences growth. OsmiPEP162a-edited plants exhibited reduced plant height, similar to mature OsmiR162-edited plants. Transcriptome-focused molecular analysis unveiled significant alterations in transcription profiles following the depletion of OsmiPEP162a. In addition, knocking out OsmiPEP162a led to decreased expression levels of mature OsMIR162a and OsMIR162b. This study suggests that OsmiPEP162a potentially plays a crucial role in stabilizing mature OsMIR162.