Genome-wide identification of HSP90gene family in Rosa chinensisand its response to salt and drought stresses

Heat shock protein 90 (HSP90) is important for many organisms, including plants. Based on the whole genome information, the gene number, gene structure, evolutionary relationship, protein structure, and active site of the HSP90 gene family in Rosa chinensisand Rubus idaeuswere determined, and the expression of the HSP90gene under salt, and drought stresses in two rose varieties Wangxifeng and Sweet Avalanche were analyzed. Six and eight HSP90genes were identified from R. chinensisand Ru. idaeus, respectively. Phylogenetic analysis revealed that the analyzed genes were divided into two Groups and four subgroups (Classes 1a, 1b, 2a, and 2b). Although members within the same classes displayed highly similar gene structures, while the gene structures and conserved domains of Group 1 (Class 1a and 1b) and the Group 2 (Class 2a and 2b) are different. Tandem and segmental duplication genes were found in Ru. idaeus, but not in R. chinensis, perhaps explaining the difference in HSP90gene quantity in the two analyzed species. Analysis of cis-acting elements revealed abundant abiotic stress, photolight-response, and hormone-response elements in R. chinensisHSP90s. qRT-PCR analysis suggested that RcHSP90-1–1, RcHSP90-5–1and RcHSP90-6–1in Sweet Avalanche and Wangxifeng varieties played important regulatory roles under salt and drought stress. The analysis of protein structure and active sites indicate that the potential different roles of RcHSP90-1–1, RcHSP90-5–1, and RcHSP90-6–1in salt and drought stresses may come from the differences of corresponding protein structures and activation sites. These data will provide information for the breeding of rose varieties with high stress resistance.