The in vivo performance of a heat shock transcription factor from Populus euphratica, PeHSFA2, promises a prospective strategy to alleviate heat stress damage in poplar

Heat stress driven by global warming has affected forest yields and survival at a larger scale in recent decades, hence breeding heat-tolerant tree species has become imperative. We here investigated the role of PeHSFA2, a crucial gene in plant heat shock response from Populus euphratica, in regulating plant heat stress protection. PeHSFA2 is localized to the cytoplasm and nucleus and can be transported from the cytoplasm into the nucleus under detrimental high-temperature conditions. Poplar plants with overexpressed PeHSFA2 outperformed the control group when subjected to severe heat stress, for they had higher leaf water content, lower leaf relative electrolyte leakage, and better photosynthetic activity after heat treatment. The results of qRT-PCR analyses revealed that PeHSFA2 regulates the transcription of a group of heat-protective genes including small heat shock protein, GALACTINOL SYNTHASE 2.2, and ASCORBATE PEROXIDASE 2 in white poplar. Transactivation assays confirmed that PeHSFA2 activated the expression of PtoHSP19.9, PtoHSP21.3, PtoHSP21.8, PtoHSP22.0, PtoGOLS2.2, and PtoAPX2 via binding to the promoter regions of these genes. These results emphasize the point that PeHSFA2 can vehemently reinforce plant thermotolerance via regulating the transcription of a set of heat shock response genes, and PeHSFA2 possesses enormous potential in breeding poplar plants with substantially enhanced thermotolerance.