Role of small RNAs in abiotic stress responses in plants

Abiotic stresses in plants are responsible for considerable yield losses globally. Scientific efforts have been made in understanding the complex stress-response mechanisms. Abiotic stress responses in plants have been known to be associated with the regulation of specific gene expression at the transcriptional and translational level. However, various studies over the years have demonstrated the role of endogenous small RNAs (sRNAs) like micro RNAs (miRNAs), short interfering RNAs (siRNAs), trans acting siRNAs (ta-siRNAs), natural antisense transcript derived siRNAs (nat-siRNAs) and piwi interacting RNAs (piRNAs) in plant abiotic stress response. sRNAs are involved in abiotic stresses like drought and salinity stress, oxidative and mineral nutrient deficiency, thermal (cold and heat) stress etc. These sRNAs are differentially expressed during various abiotic stress responses and repression of target gene expression appears to be the major mechanism of action to combat abiotic stresses (Fig. 1). High throughput techniques have been instrumental in identification and characterization of various stress associated sRNAs in plants. Utilization of innovative bioinformatical and computational tools has also contributed immensely towards genome wide identification of sRNAs and their target genes. In the future, RNA interference approach mediated by various sRNAs can be used for development of transgenic plants aimed for combating abiotic stress tolerance in plants. This review focuses on (i) interpretation and understanding of the roles of various sRNAs involved in abiotic stress tolerance (ii) identification of sRNAs involved in abiotic stress tolerance and study of sRNA-target gene interaction and validation.