Arginine-rich motif-tandem CCCH zinc finger proteins in plant stress responses and post-transcriptional regulation of gene expression.

Tandem CCCH zinc finger (TZF) proteins are evolutionarily conserved regulators of gene expression at the post-transcriptional level. TZFs target AU-rich RNA elements at 3' un-translated region and recruit catabolic machineries to trigger mRNA degradation. The plant TZF families are over-represented by a class of proteins with a unique TZF domain preceded by an arginine-rich motif (RR-TZF). RR-TZF proteins are mainly involved in hormone- and environmental cues-mediated plant growth and stress responses. Numerous reports have suggested that RR-TZF proteins control seed germination, plant size, flowering time, and biotic and abiotic stress responses via regulation of gene expression. Despite growing genetic evidence, the underlying molecular mechanisms are elusive. This review outlines the highly conserved roles of plant RR-TZFs in various stress responses and the potential involvements of RR-TZF proteins in transcriptional and post-transcriptional regulation of gene expression. The dynamic subcellular localization of RR-TZF proteins, implication of predominant protein-protein interactions between RR-TZF proteins and stress response mediators and future directions of this research field are also discussed.