Role of microRNAs in mediating biotic and abiotic stress in plants

Plants being sessile, are exposed to several biotic and abiotic stresses in their natural habitat. The abiotic stress involves stress due to low temperature or high temperature, high salinity, deficiency or excessive water, heavy metals, and ultraviolet radiation, among others. The biotic stress is caused by several biotic agents like that of bacteria, virus, nematode, insects, and fungi. Every year, the biotic and abiotic stress results in severe losses to the production of agricultural and commercial plants. It has been seen that there was differential expression of several miRNAs (micro RNAs), in response to a variety of biotic and abiotic stress. Since miRNAs are important contributors to plant stress response, identifying the miRNA and characterizing their target gene is important. The miRNAs are small noncoding RNAs, comprising of 20-24 nucleotides in length, that are capable of regulating gene expression. The review will summarize the findings, regarding several specific miRNAs whose differential expression plays a role in plant stress tolerance, and thus mediating the expression of those miRNAs, may contribute to plant stress tolerance.