Modulation of miRNA expression in natural populations of A . thaliana along a wide altitudinal gradient of Indian Himalayas

Plant populations growing along an altitudinal gradient are exposed to different environmental conditions. They are excellent resources to study regulatory mechanisms adopted by plants to respond to different environmental stresses. Regulation by miRNA is one of such strategies. Here, we report how different miRNAs are preferentially expressed in the three natural populations of A . thaliana originating from a wide altitudinal range. The expression level of miRNAs was mostly governed by temperature and radiation. Majority of the identified miRNAs expressed commonly in the three populations. However, 30 miRNAs expressed significantly at different level between the low and the high altitude populations. Most of these miRNAs regulate the genes associated with different developmental processes, abiotic stresses including UV, cold, secondary metabolites, etc. Further, the expression of miR397 and miR858 involved in lignin biosynthesis and regulation of secondary metabolites respectively, may be regulated by light intensity. A few miRNAs expressed at increasing level with the increase in the altitude of the site indicating environment driven tight regulation of these miRNAs. Further, several novel miRNAs and isomiR diversity specific to the Himalayas are reported which might have an adaptive advantage. To the best of our knowledge, this is the first report on miRNA expression from natural plant populations.