Genome-Wide microRNA Profiling Using Oligonucleotide Microarray Reveals Regulatory Networks of microRNAs in Nicotiana benthamiana During Beet Necrotic Yellow Vein Virus Infection

(BNYVV) infections induce stunting and leaf curling, as well as root and floral developmental defects and leaf senescence in . A microarray analysis with probes capable of detecting 1596 candidate microRNAs (miRNAs) was conducted to investigate differentially expressed miRNAs and their targets upon BNYVV infection of plants. Eight species-specific miRNAs of were identified. Comprehensive characterization of the microRNA profile in response to the BNYVV infection revealed that 129 miRNAs were altered, including four species-specific miRNAs. The targets of the differentially expressed miRNAs were predicted accordingly. The expressions of miR164, 160, and 393 were up-regulated by BNYVV infection, and those of their target genes, , , and , were down-regulated. , which is a target of miR396, was also down-regulated. Further genetic analysis of by -induced gene silencing, assay confirmed the involvement of in the symptom development during BNYVV infection. BNYVV infection also induced the up-regulation of miR168 and miR398. The miR398 was predicted to target , and silencing of could enhance plant resistance against viruses, suggesting the activation of primary defense response to BNYVV infection in . These results provide a global profile of miRNA changes induced by BNYVV infection and enhance our understanding of the mechanisms underlying BNYVV pathogenesis.