Abstract: MiR396 was a single-stranded noncoding small RNA with 21 nucleotides, and the expression of MiR369 in leaves was strongly induced in water deficit condition in tobacco , which suggested a possible role of miR396 in drought stress response. Under the control of 35S promoter, MIR396 was introduced into tobaccomediated by Agrobacterium tumefaciens. Physiological tests indicated that the elevated levels of miR396 increased drought tolerance in tobacco accompanying with lower water loss rate and higher relative water content. Further more miR396-overexpressing plants exhibited visible reductions both in stomatal density and stomatal index as well as a narrow and small leaf phenotype in comparison with wild- type plants. The present study indicated that miR396 was a positive regulator in response to drought stress in tobacco .

Key words: miR396