Genome-Wide Identification and Expression Analysis of Hsf and Hsp Gene Families in Cucumber (Cucumis Sativus L.)

Abstract Heat shock proteins (Hsps) are molecular chaperones that participate in plants' response to environmental stresses, including heat stress, and also play an essential role in plant growth and development. Hsps expression is monitored and regulated by specific types of transcription factors known as heat shock factors (Hsfs). Although the role of Hsfs and Hsps in stress response has been investigated in some plants, their role is still poorly understood in cucumber (Cucumis sativus L.). To reveal the mechanisms of cucumber Hsf and Hsp coping with various stresses, the analyses of cucumber Hsf and Hsp gene families were conducted using bioinformatics-based methods. A total of 23 Hsfs and 72 Hsps were identified in the cucumber genome (v3.0), and the gene structure and motif composition are relatively conserved in each subfamily. At least 23 pairs of heat shock genes underwent gene duplication in cucumber. A cis-element analysis is implicit that CsHsfs and CsHsps possessed at least one hormone or stress response cis-element, suggesting that CsHsf and CsHsp genes could respond to different stress conditions. Heatmaps of the CsHsf and CsHsp gene families indicated that most heat shock genes were expressed in different tissues and organs. RNA-seq showed that most of the cucumber Hsf and Hsp genes are differentially expressed upon exposure to biotic and abiotic stresses. These results provide valuable information to clarify the evolutionary relationship between the CsHsf and CsHsp family and to facilitate the functional characterization of the CsHsf and CsHsp genes in future studies.