RNAi Mediated Drought and Salinity Stress Tolerance in Plants

Abstract

RNAi mediated gene silencing demonstrated to serve as a defence mechanism against abiotic stress. Some endogenous small RNAs (microRNA and siRNA) have emerged as important players in plant abiotic stress response. Drought and salinity are the major environmental stresses that limit the agricultural food production. miRNA involved in drought and salinity stress response, including ABA response, auxin signalling, osmoprotection and antioxidant defence by downregulating the response target gene. It is observed that some of the microRNAs are upregulated or downregulated in response to drought and salt stress. We reviewed that miR167, miR393, mir474, miR169g are upregulated whereas miR168, miR396, miR397 are downregulated in rice plant during drought stress. Moreover, our detail categorical analysis on the basis of mechanism of action found that miRNA involved in drought stress was 28% in ABA signalling and response, 14.2% in auxin signalling, 9.52% in miRNA processing, 14.2% in cell growth, 9.52% in antioxidant defence, 4.76% in CO2 fixation and 9.52% in osmotic adjustment. Similarly, miRNA involved in salinity stress was 5.8% in auxin signalling, 23.5% in vegetative phase change and root, shoot, leaf and vascular development, 11.76% in gynoecium and stamens development, 8.82% in metabolic adaptation, 2.74% in early embryogenesis and 41.17% not known. Importantly, some common miRNAs such as miR159, miR167, miR169, miR393 and miR397 play an important role in both drought and salinity stress conditions. Here, in this review, we mainly focused on the current status of miRNAs, mechanism of action and their regulatory network during drought and salinity stress in plants.

Non-Coding RNAs in Response to Drought Stress

“…Similarly, the downregulation of miR159 in drought triggered the expression of HD-ZIP, ARF and GA-MYB transcription factors, which contributed to greater adventitious and lateral root formation. Moreover, miR474 was upregulated in drought to inhibit proline dehydrogenase (PDH) [306], while miR827 was upregulated during drought stress to act on NADP-binding and SPX (SYG1/Pho81/XPR) transcripts to activate stress signal transduction pathways [305].…”

Gene regulation at transcriptional and post‐transcriptional levels to combat salt stress in plants

“…This regulates the formation of protective metabolites which ultimately enhance the tolerance level of the plants. The entire process is further amplified by the activity of RNA‐dependent RNA‐polymerase (RDRP; Pradhan et al, 2015)…”

“…This regulates the formation of protective metabolites which ultimately enhance the tolerance level of the plants. The entire process is further amplified by the activity of RNA-dependent RNA-polymerase (RDRP;Pradhan et al, 2015) level in A. thaliana. The plants having mutant skip-1 showed premature termination of translation, thus generating non-functional proteins due to retention of introns, mostly containing termination codons in the premature mRNA, thereby reducing the tolerance level of the mutant plants Wang et al (2012).…”

A Comparative Study of ESTs Induced under Drought and Salinity Stress in Hyacinth Bean (<i>Lablab purpureus</i>)

“…Transcription factor families like NAC [13], WRKY [14], DERB [15] [16], are reported to be differentially regulated under stress. Specific protein like defensins, SpPKE1 [17], cysteine proteases [18], RING finger protein [19] an E3 ubiquitin ligase [20] and genes modified using RNAi mediated gene silencing [21] are known to increase tolerance towards abiotic stress.…”