Salt Stress Induces Complicated miRNA Responses of Sugar Beet (Beta vulgaris L.)

Although sugar beet has a high salt tolerance, the quantity and characteristics of miRNAs and their potential effects on salt stress response remain unclear. The leaves of beet variety "N98122" were used for miRNA sequencing at 0, 2.5, 7.5, and 16h. The results showed that small RNAs of 21 nt had the highest abundance, followed by those of 22 and 23 nt. In total, 654 differential miRNAs, comprising 24 known and 630 novel miRNAs, were determined from seedlings treated with NaCl for 0, 2.5, 7.5, and 16h. Of the 24 known miRNAs, 17 exhibited downregulated expression, including miR159, miR166, miR1873, miR319, miR3626, miR3699, and miR397, and seven miRNAs exhibited upregulated expression, including miR156, miR3630, miR481, miR4995, miR5369, miR536, and miR6173. GRF, HKT, PAGR, SDK, Eps1511, VPS, PAN, 1-Sep, CFDP, DRG, DET, IFRD, PSA, mfsd, and ANTR were determined as the target genes of the differentially expressed miRNAs. The outcomes of this study offer important information about miRNAs that respond to salt conditions, and this knowledge may prove useful for enhancing the tolerance of sugar beet to salt stress.