miR2118 Negatively Regulates Bacterial Blight Resistance through Targeting Several Disease Resistance Genes in Rice.

Plant miRNAs are a class of noncoding RNA with a length of 21-24 nt that play an important role in plant responses to biotic and abiotic stresses. Bacterial blight (BB) caused by pv. () is one of the most serious bacterial diseases in rice. Our previous work showed that osa-miR2118b/n was induced by infection. However, the biological function of miR2118 has not yet been characterized in experiments. Herein, we constructed OE, as well as single and double mutants of using CRISPR/Cas9. Further results showed that osa- OE plants exhibited longer lesion lengths than the wild type after inoculation, while CRISPR plants exhibited shorter lesion lengths than the wild type after inoculation. Co-transformation experiments in rice protoplasts indicated that osa-miR2118 negatively regulated the transcripts of three nucleotide-binding sites and leucine-rich repeat (NLR) genes (, , and ) which are predicted target genes of miR2118, but not the mutated NLR genes with a 3 bp insertion at the center of the binding sites. The transcriptional level of the three NLR genes was reversed relative to osa-miR2118 in the OE and CRISPR plants. The above results demonstrate that osa-miR2118b/n negatively regulates the resistance to bacterial blight through negatively regulating several NLR genes.