miRNA plays a role in the antagonistic effect of selenium on arsenic stress in rice seedlings

MicroRNAs (miRNAs), the small non-coding RNAs, have been implicated in various biological processes including adaptation during environmental stress. The present work explores the involvement of miRNA during arsenic (As) and selenium (Se) treatment in rice seedlings. Arsenic is a heavy metalloid causing severe adverse effects on the growth and development of plants while Se is another metalloid and an essential micro-nutrient when present in appropriate amounts. It was observed that the presence of Se along with As mitigated the adverse effects of As on seedling germination, root-shoot growth, total chlorophyll and protein contents. The measurement of stress indicators such as proline, cysteine and MDA also indicated similar effects. Analysis of the miRNA profile using microarrays under As, Se and As + Se treatments showed differential regulation of at least 46 miRNAs in rice seedlings compared to untreated control. 18 of these miRNAs showed differential regulation among different treatments. Furthermore the microarray data were validated using real time PCR. The target genes of a few of these miRNAs showed inverse transcript accumulation. The possible role of miR395 and miR398 in the antagonistic effect on the adverse response of As in the presence of Se in rice seedlings is discussed.