Comprehensive identification and analyses of the Hsf gene family in the whole-genome of three Apiaceae species

Apiaceae is a major family from Apiales and includes many important vegetable and medicinal crops. Heat shock transcription factors (Hsf) play important roles in heat tolerance during plant development. Here, we conducted systematic analyses of the Hsf gene family in three Apiaceae species, including 17 Apium graveolens (celery), 32 Coriandrum sativum (coriander), and 14 Daucus carota (carrot). A total of 73 Hsf genes were identified in three representative species, including Arabidopsis thaliana, Vitis vinifera, and Lactuca sativa. Whole-genome duplication played important roles in the Hsf gene family's expansion within Apiaceae. Interestingly, we found that coriander had more Hsf genes than celery and carrot due to greater expansion and fewer losses. Twenty-seven branches of the phylogenetic tree underwent considerable positive selection in these Apiaceae species. We also explored the expression patterns of Hsf genes in three plant organs. Collectively, this study will serve as a rich gene resource for exploring the molecular mechanisms of heat tolerance. Additionally, this is the first study to report on the Hsf gene family in Apiaceae; thus, our research will provide guidance for future comparative and functional genomic studies on the Hsf gene family and others in Apiaceae.