Figure 1. Hsf gene family and their phylogenetic relationships in P. euphratica (Peu), P. trichocarpa (Pt), S. suchowensis (Ssu), and A. thaliana (At).

(a) The members of Hsf from four species were classified into three mainly subfamilies (class A, B, and C). (b) The phylogenetic tree was constructed using full-length of amino acid sequences of Hsf proteins in the four species by the neighbor-joining (NJ) method with 1,000 bootstrap replicates. Bootstrap support values are indicated on each node.