Small RNA-Mediated Defensive and Adaptive Responses in Plants

Abstract

Agriculture is the backbone of economy for most countries, especially the developing countries with high population density. However, the change in climate and its influence on the environment has led to low productivity of several staple crops that can be attributable to prevailing biotic and abiotic factors. In the long run, these factors are likely to have more adverse effects on the crop yield than what is currently being encountered. Therefore, scientists across the world develop strategies to tackle future problems leading to food insecurity. Plants are exposed to a variety of stresses under natural conditions. To encounter these challenges plants have efficiently evolved with several endogenous mechanisms to defend themselves against such harmful situations. Small ribonucleic acids (sRNA) have recently been identified as critical molecules that regulate wide variety of biological phenomenon, both in plants and animals. Several lines of evidence demonstrates that small RNAs profiles changes rapidly in response to adverse stimuli. In certain cases, specific small RNAs were found to be associated with a particular stress, thus, indicating the direct involvement of small RNA-mediated pathways in plethora of stresses. We review here the advancements of small RNA biology, including microRNA and short-interfering RNA, and aspects related to their possible role in counter defense of biotic and abiotic stress responses. The review has been broadly classified into two sections describing role of small RNAs assigned in response to various biotic and abiotic stresses. The possible evidence of cross-talk among diverse range of stresses is also discussed. Future investigations may explore putative novel pathways downstream to this small RNA misexpression and consequently open avenues to design strategies to raise transgenic crops resistant to multiple stresses.