Genome-wide identification of HSF gene family and their expression analysis in vegetative tissue of young seedlings of hemp under different light treatments

Heat shock transcription factors (HSFs), play a crucial role in plant growth, development and defense processes. The functions of some HSFs have been well studied in response some stresses in model plants. At present, the genome of the medicinal plant Cannabis sativa L. has been fully sequenced. Nevertheless, there is little known about the HSF genes family in Cannabis sativa L, as well as a lack of understanding of its evolutionary history. Herein, 18 HSFs were identified in the cannabis genome and phylogenetically classified into three groups based on the structural characteristics and phylogenetic analysis, including classes A (9 genes), classes B (8 genes), and classes C (1 gene). They were distributed over 9 of 10 chromosomes without chromosome 8. Then, the motif composition and evolutionary relationship of CsHSF proteins are discussed in detail, along with gene structures, cis-acting elements in the promoter, and synchronization analysis. Furthermore, our results also revealed that CsHSF transcription levels varied significantly among tissues, suggesting that the functions of CsHSF may be different. Finally, we found that red and blue light treatments had a significant effect on HSF genes expression and cannabinoids accumulation in vegetative organs of hemp young seedlings, implying the expression of HSF genes may regulate the content of cannabinoids under different light conditions. Although cannabinoid biosynthesis and response to light in vegetative organs of hemp young seedlings may not represent the mature stage of hemp, these results provided an essential theoretical basis to elucidate the regulatory mechanism of HSF in cannabinoid biosynthesis in the future.