The Role of Class A1 Heat Shock Factors (HSFA1s) in Response to Heat and Other Stresses in Arabidopsis

In Arabidopsis, there are four homologs of class A1 HEAT SHOCK FACTOR (HSF) genes, which likely encode the master regulators of heat-shock response (HSR). However, previous studies with double knockout mutants were unable to confirm this point probably due to functional redundancy. We generated a quadruple knockout and four triple knockout mutants to dissect their functions. Our data show that members of the HSFA1-group not only play a pivotal role in HSR but also are involved in growth and development. Alterations in morphology and retardation in growth were observed in the quadruple but not in triple knockout mutants. The basal and acquired thermotolerance capacity was dramatically decreased in the quadruple knockout mutant, but varied in triple knockout mutants at different developmental stages. The transcriptomics profiles suggested that more than 65% of the HS-upregulated genes were HSFA1-dependent. HSFA1s were also involved in the expression of several HS genes induced by H2O2, salt, and mannitol, which is consistent with the increased sensitive phenotype of the quadruple knockout mutant to the stress factors. In conclusion, the Arabidopsis HSFA1s function as the master regulators of HSR and participate as important components in other abiotic stress responses as well.


Co-researchers:Hsiang-chin Liu, Hsiu-ting Liao