of Positively Regulate Thermotolerance by Transcriptionally Activating and .

Heat shock transcription factors (HSFs) are crucial components in heat stress response. However, the contribution of the HSFs governing the inherent thermotolerance in has barely been investigated. We here compared the roles of , , and in heat stress tolerance. These three genes are the results of gene duplication events, but there exist vast variations in their amino acid sequences. They are all localized to the nucleus. plants with overexpressed and outperformed the wild-type plants, while the over-accumulation of had little impact on plant thermotolerance. By transiently overexpressing , , and in seedlings, the mRNA abundance of heat shock response genes, including , , , , , and , were upregulated. Transactivation assays confirmed that there exist regulatory divergences among these three genes, viz., has the highest transcription activity in regulating , , , and ; can transcriptionally activate , , and ; makes limited contributions to the accumulation of , , and . Our results indicate that the genes make crucial contributions to the thermal adaption of by positively regulating the , , and genes, which provides novel insights into the subfamily.