A phylogenetic analysis was performed and 8 Beta lineage-specific miRNAs were identified. Through a differential expression analysis, miRNAs associated with Beet necrotic yellow vein virus (BNYVV) infection were identified and confirmed using microarray analysis and stem-loop RT-qPCR. In total, 103 known miRNAs representing 38 miRNA families, and 45 potential novel miRNAs were differentially regulated, with at least a two-fold change, in BNYVV-infected plants compared with that of the mock-inoculated control. Targets of these differentially expressed miRNAs were also predicted by degradome sequencing. These differentially expressed miRNAs were involved in hormone biosynthesis and signal transduction pathways, and enhanced axillary bud development and plant defenses.
This work is the first to describe miRNAs of the plant genus Beta and may offer a reference for miRNA research in other species in the genus. It provides valuable information on the pathogenicity mechanisms of BNYVV.
The size distribution of total (A) or unique (B) beet-derived small RNAs and total (C) or unique (D) miRNAs in two libraries. L, small RNA library from leaves; VL, from BNYVV-infected leaves; nt, nucleotide.