Variability of plant heat shock factors: regulation, interactions and
In plants Heat Shock Factors (HSFs) are encoded by large gene families
and are primary regulators of responses not only to high temperatures
but also to a number of other abiotic stresses and pathogen threats.
Here we provide an overview of the diverse world of the plant HSFs
through analysis of their functional versatility, regulation and
interactions. HSFs can regulate tolerance to a number of extreme
conditions including high or low temperatures, drought, hypoxic
conditions, soil salinity, toxic minerals, strong irradiation or
pathogen defenses. Variability is reflected in expression control with
considerable differences in transcript profiles of individual HSF genes.
Moreover, alternative splicing and posttranslational modifications
provides further variability. HSFs are involved in complex web of
protein-protein interactions which include formation of homomeric and
heteromeric HSF trimers, and complexes with a number of other regulatory
proteins including transcription regulators, chromatin-associated
proteins or heat shock proteins (HSPs). Interactions of the Arabidopsis
HSFA4A with proteins which control transcription, cellular homeostasis,
responses to different stresses and programmed cell death, illustrate
the complexity of the regulatory networks related to a plant HSF.
Diversity in plant HSFs facilitates the adaptation to multiple adverse
environmental conditions, an important feature in response to climate