PtHSFA4a gene play critical roles in the adaptation of Arabidopsis thaliana plants to high-Zinc stress.

Heat shock transcription factors (HSFs) play pivotal roles in various abiotic stresses. However, only one of the studies on HSFs that participated in excess zinc (Zn) stress in our previous study in Populus ussuriensis. Here, overexpression of P. trichocarpa PtHSFA4a gene in Arabidopsis thaliana significantly improved excess Zn tolerance. It was found that PtHSFA4a-OE lines have higher seed germination rate than wild type (WT) when exposed to excess Zn. Also, PtHSFA4a-OE lines exhibit high viability and stronger root growth than WT in soil. PtHSFA4a reduced the intracellular concentration of free zinc ion of roots when overexpressed in A. thaliana. Our data indicate PtHSFA4a is the candidate gene to act as positive regulators in the resistance to excess Zn, extending our knowledge of excess Zn tolerance transcription factors.