Overexpressing osa-miR171c decreases salt stress tolerance in rice

The miRNA171 family is one of the well-conserved miRNA families, and its role under stresses is not known except its expression on genome-wide expression analyses. osa-miR171c was induced by high concentration of salt (150 mM NaCl). A rice dh mutant with osa-miR171c overexpression triggered by a T-DNA insertion, significantly decreased salt tolerance at the stages of germination and seedling. This phenotype was confirmed by osa-miR171c overexpression transgenic rice. Compared with wild-type (WT), dh mutant reduced amounts of free proline and increased the water loss rate after salt treatment. Stomatal density in the leaf epidermis of dh mutant also increased. Moreover, dh mutant increased sensitivity to ABA treatment. Several stressresponsive genes were down-regulated in dh mutant than in WT under salty stress. These results indicate that osamiR171c is involved in modulating physiological changes, stomatal development, ABA-dependent pathways and expression of stress-related genes; thereby, it possibly contributes to salty tolerance.