Dehydrin in the past four decades: From chaperones to transcription co-regulators in regulating abiotic stress response

Dehydrins are a multifunctional and diverse class of proteins that are crucial in combating abiotic stresses imposed on the plant kingdom. Plants use dehydrin to stabilize biomolecules and membranes; therefore, dehydrins are key during dehydration stress. For almost 30 years, dehydrins have been known to be chaperones that enable ion-binding functions, act as a cryo-protectants and aid in free radical scavenging. Other functions of dehydrin have been explored more recently, and the results suggest that dehydrin might have roles beyond its chaperone functions. First, dehydrin has recently been found to regulate stress-responsive genes, and evolution has enabled dehydrins to participate in the cell's transcription regulatory machinery during the stress response. Second, dehydrins have been reported to play an indirect role in histone modification. In this epigenetic process, H3K4me3 modification is positively associated with the expression of dehydrin and other drought-responsive genes. This review describes the details of studies on dehydrin from its discovery until 2021, thus providing a progressive, complex, interlinked and comprehensive understanding of the dehydrin gene family. In addition, biotechnologies and integrative approaches that have aided in exploring the varying dynamics of dehydrin spatially and temporally are discussed.