Heat Shock Factors: Regulators of Early and Late Functions in Plant Stress Response

Abstract

Heat shock factors (HSFs) among others are of great importance regarding the regulation of increased stress tolerance. Based on structural characteristics and phylogenetic comparison plant HSFs are subdivided into 3 classes and several subgroups. Recent studies showed that different HSFs play important roles during early and late stages of stress response. In this review, we focus mainly on the functional characterisation of class A HSFs of Arabidopsis, which are known to function as transcriptional activators of stress target genes. Recent evidence obtained from the identification of HSF-knockout mutants and microarray expression profiling indicates that different early and late HSF regulate large numbers of partially overlapping sets of target genes. Meta-analysis of microarray data generated from different experimental setup may have the potential to verify known and/or to identify novel HSF target genes. In addition, we will summarise recent work on the potential roles of oxidative stress leading to the activation of HSFs and the induction of the heat stress response. _____________________________________________________________________________________________________________