RNAi Mediated Hypoxia Stress Tolerance in Plants

Abstract

Small RNAs regulate various biological process involved in genome stability, development, and adaptive responses to biotic or abiotic stresses. Small RNAs include microRNAs (miRNAs) and small interfering RNAs (siRNAs). MicroRNAs (miRNAs) are regulators of gene expression that affect the transcriptional and post-transcriptional regulation in plants and animals through RNA interference (RNAi). miRNAs are endogenous small RNAs that originate from the processing of non-coding primary miRNA transcripts folding into hairpin-like structures. The mature miRNAs are incorporated into the RNA-induced silencing complex (RISC) and drive the Argonaute (AGO) proteins towards their mRNA targets. siRNAs are generated from a double-stranded RNA (dsRNA) of cellular or exogenous origin. siRNAs are also involved in the adaptive response to biotic or abiotic stresses. The response of plants to hypoxia includes a genome-wide transcription reprogramming. However, little is known about the involvement of RNA signaling in gene regulation under low oxygen availability. Interestingly, miRNAs have been shown to play a role in the responses to hypoxia in animals, and recent evidence suggests that hypoxia modulates the expression of various miRNAs in plant systems. In this review, we describe recent discoveries on the impact of RNAi on plant responses to hypoxic stress in plants.

Keywords: RNAi; argonaute; hypoxia; miRNAs.

Figure 1

Influence of hypoxia on the RNAi machinery in plants. Under hypoxia mitochondrial activity is largely prevented due to the lack of oxygen. This is likely to be one of the factors triggering the production of some hypoxia-related miRNAs which, by relying on the activity of AGO1, contribute to hypoxia tolerance. Hypoxia tolerance is also influenced by AGO4, which controls RNA-dependent DNA-methylation pathways. The stabilization of the transcription factor RAP2.12 activates the transcription of AGO3, whose role in RNAi is still largely unknown.