miRNA regulation and stress adaptation in plants

Plant microRNAs (miRNAs) are small non-coding RNAs regulating of genes involved in major physiological processes including growth, development, and responses to biotic and abiotic stressors. Abiotic environmental stressors including drought, high or low temperature, salinity, and heavy metals may potentially cause extensive damage to plants, including to nuclear and organelle DNA. In this complex scenario miRNAs play a fundamental regulatory role. Although considerable evidence has accumulated about regulation by miRNAs at cellular and tissue levels, wide differences in experimental design make interpretation difficult. This review attempts to provide a picture of the major response pathways where miRNAs are involved, making use of system biology to highlight the level of preservation of the response to environmental abiotic stress, with particular regards to adaptive and sequence variation of nuclear and organelle genomes. Elucidation of miRNA responses to abiotic stress implicated in genome stress response may lead to the generation of tools for early monitoring of plant environmental stressors.