Identification and characterization of microRNAs in virus-resistant and susceptible barley cultivars

Barley (Hordeum vulgare L.) is the fourth most productive cereal crop in the world, but barley sown in winter is often infected by the barley yellow mosaic virus (BaYMV) and the barley mild mosaic virus (BaMMV), which cause mosaic, stunting, discoloration and yield reduction. Plant microRNA (miRNA) plays a major part in defense against viral infection. In this study, total sRNAs from the leaves of three barley cultivars infected with a soil-borne virus, BaYMV or BaMMV, were analyzed by RNA sequencing. A total of 35 known miRNAs and 70 novel miRNAs were identified, of which hvu-miR397a and huv-miR156a were most differentially expressed. A total of 18 miRNAs were found to target 259 genes. Enrichment analysis revealed that targeted genes were associated with chloroplast functions. Overall, the results provided a whole landscape of small RNAs and mRNAs in response to BaYMV infection and can be referred to in plant breeding against virus infection.