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 Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious bacterial diseases in rice. Our previous work showed that osa-miR2118b/n was induced by Xoo infection. However, the biological function of miR2118 has not yet been characterized in experiments. Herein, we constructed MIR2118b OE, as well as single and double mutants of MIR2118b/n using CRISPR/Cas9. Further results showed that osa-MIR2118b OE plants exhibited longer lesion lengths than the wild type after Xoo inoculation, while MIR2118 CRISPR plants exhibited shorter lesion lengths than the wild type after Xoo 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 (LOC_Os08g42700.1, LOC_Os01g05600.1, and LOC_Os12g37290.1) 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 MIR2118b OE and MIR2118b CRISPR plants. The above results demonstrate that osa-miR2118b/n negatively regulates the resistance to bacterial blight through negatively regulating several NLR genes.

Overexpression of miR169o, an Overlapping MicroRNA in Response to Both Nitrogen Limitation and Bacterial Infection, Promotes Nitrogen Use Efficiency and Susceptibility to Bacterial Blight in Rice.

Limiting nitrogen (N) supply contributes to improved resistance to bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) in susceptible rice (Oryza sativa). To understand the regulatory roles of microRNAs (miRNAs) in this phenomenon, 63 differentially expressed overlapping miRNAs in response to Xoo infection and N limitation stress in rice were identified through deep RNA sequencing and stem-loop quantitative real-time PCR. Among these, miR169o was further assessed as a typical overlapping miRNA through the overexpression of the miR169o primary gene. Osa-miR169o-OX plants were taller, and had more biomass accumulation with significantly increased nitrate and total amino acid contents in roots than the wild type (WT). Transcript level assays showed that under different N supply conditions, miR169o oppositely regulated NRT2, and this is reduced under normal N supply conditions but remarkably induced under N-limiting stress. On the other hand, osa-miR169o-OX plants also displayed increased disease lesion lengths and reduced transcriptional levels of defense gene (PR1b, PR10a, PR10b and PAL) compared with the WT after inoculation with Xoo. In addition, miR169o impeded Xoo-mediated NRT transcription. Therefore, the overlapping miR169o contributes to increase N use efficiency and negatively regulates the resistance to BB in rice. Consistently, transient expression of NF-YA genes in rice protoplasts promoted the transcripts of PR genes and NRT2 genes, while it reduced the transcripts of NRT1 genes. Our results provide novel and additional insights into the co ordinated regulatory mechanisms of cross-talk between Xoo infection and N deficiency responses in rice.

Unified Treatment for Plasmon-Exciton Co-driven Reduction and Oxidation Reactions.

Revealing the nature of plasmon-exciton co-driven surface catalytic reactions is important and urgent for developing potential applications in energy and environmental science. In this work, we propose a mechanism for plasmon-exciton co-driven surface catalytic reactions based on our experimental results. We provide a method for a unified treatment for reduction and oxidation reactions, which not only strongly supports our proposed mechanism but also promotes a deeper understanding of plasmon-exciton co-driven surface catalytic reactions.