Phylogenetic relationships, gene structure, and protein structures of the sHsp genes in Salix suchowensis. (a) Multiple alignment of Hsp20 domain was executed using Clustal X2.1 and a phylogenetic tree was constructed using MEGA 6.06 by the neighbor-joining (NJ) method with 1000 bootstrap replicates. (b) The exon/intron structures of the Ssu-sHsps genes. Boxes represent exons and lines represent introns. The numbers indicate the splicing phases of the Ssu-sHsps: 0, phase 0; 1, phase 1; and 2, phase 2. (c) The protein structures of the Ssu-sHsp proteins. Red boxes represent the Hsp20 domain.