Plant RNA Binding Proteins as Critical Modulators in Drought, High Salinity, Heat, and Cold Stress Responses: An Updated Overview

Abstract

Plant abiotic stress responses are tightly regulated by different players at multiple levels. At transcriptional or post-transcriptional levels, several RNA binding proteins (RBPs) regulate stress response genes through RNA metabolism. They are increasingly recognized as critical modulators of a myriad of biological processes, including stress responses. Plant RBPs are heterogeneous with one or more conservative RNA motifs that constitute canonical/novel RNA binding domains (RBDs), which can bind to target RNAs to determine their regulation as per the plant requirements at given environmental conditions. Given its biological significance and possible consideration as a potential tool in genetic manipulation programs to improve key agronomic traits amidst frequent episodes of climate anomalies, studies concerning the identification and functional characterization of RBP candidate genes are steadily mounting. This paper presents a comprehensive overview of canonical and novel RBPs and their functions in major abiotic stresses including drought, heat, salt, and cold stress conditions. To some extent, we also briefly describe the basic motif structure of RBPs that would be useful in forthcoming studies. Additionally, we also collected RBP genes that were modulated by stress, but that lacked functional characterization, providing an impetus to conduct further research.

Keywords: RNA metabolism; abiotic stress; plant RNA binding proteins; post transcriptional gene regulation.

Figure 1

A simplified diagrammatic representation of activation of RBP and other genes by abiotic stress signals (drought, salt, heat, and cold) and RBP interactions with RNAs of nuclear, chloroplast, and the mitochondrion at various levels to regulate stress responses in a plant cell. The stress signals perceived by the sensors were transduced to the nucleus, where activation of several genes, including RBP genes, was happening to adjust the cellular conditions to stress. The RBPs interact with various stress response transcripts and modulate their expression by altering their stability, splicing, cellular localization, availability/degradation, and translational repressions.