Evaluation of the expression pattern of miR398 and miR477 and their gene targets on reproductive tissues of almond in response to cold stress

Almond (Prunus dulcis Mill.), as an important nut crop, requires chilling during winter to develop fruiting buds but late winter frost and early spring chilling may make damages to the reproductive tissues of this tree and therefore leads to reduction in the rate of productivity. Abiotic stresses such as cold stress affect plant development and production through alteration of the gene expression pattern. Since MiRNAs are known to play important roles in the regulation of stress responses via interacting with their target mRNAs, in this study, for the first time, two miRNAs with conserved sequence in different plants and associated with cold resistance, pdumiR398b and pdumiR477a-3p, were evaluated in almond. In this research, the expression study carried out on ovary and anther tissues of almond under zero and -2 °C cold stresses and control condition for 10°C in cold sensitive Sh12 variety and cold tolerant H genotype. Expression of pdu-miR398b and pdu-miR477a-3p under -2C in ovary and anther tissues in Sh12 cultivar was up-regulated while they were down-regulated in anther tissue of H genotype. Target genes of miRNAs were predicted by bioinformatics tools. There was a negative correlation between Pdu-miR398b and its predicted target gene PduDUF1639 under both cold stress treatments in Sh12 variety. Also decrease of Pdu-miR477a-3p expression in cold resistant genotype was in concomitant with over-expression of its predicted target genes, PduAAE7 and pduABC transporter. Different expression of Pdu-miR398b and Pdu-miR477a-3p and their predicted target genes in sensitive and cold resistance cultivars can be a reason that they are associated with cold stress in plant.