Genome-wide identification of GRAS transcription factor and expression analysis in response to cadmium stresses in hemp (Cannabis sativa L.)

Abstract

GRAS transcription factors play important roles in plant growth, development and stress responses. In order to systematically analyze the GRAS transcription factor family in hemp, we performed a genome-wide identification of hemp GRAS genes, analyzed their physical and chemical properties, phylogenetic development, gene structure, and GRAS gene expression under cadmium stress in two hemp varieties (Yunma 1 and Inner Mongolia Xiaolidama). The results showed that there were 54 GRAS transcription factors in hemp genome, with the protein length from 415 to 757, encoding 96.30% of acidic proteins, the molecular weight from 46,405.05 to 85,748.52 kD and the isoelectric point from 4.77 to 8.54. These transcription factors were divided into nine subfamilies, among which, PAT1, LS, SHR, and HAM were more conserved, PAT1, LISCL, and CsGRASA had a large number of tandem repeats of genes, and CSGRAS12 genes were all present in collinearity analysis of five plants. Yunma 1 and Inner Mongolia Xiaolidama were treated with cadmium stress. Plant height and the fresh weight decreased in Yunma 1 and Inner Mongolia Xiaolidama, by 10.48%, 6.33% and 66.07%, 42.67%, respectively, indicating that Yunma 1 was more tolerant than Inner Mongolia Xiaolidama under cadmium stress. Among 54 GRAS genes in Yunma 1, 42 genes (77.78%) were up-regulated by 1.05-18.10, and 11 genes (20.37%) were down-regulated by 0.13-0.91. Among 54 GRAS genes in small-grain cannabis in Inner Mongolia, 27 genes (50.00%) were up-regulated by 1.01-6.46, and 27 genes (50.00%) were down-regulated by 0.30-0.96. This study showed that the 40 homologous GRAS gene in Yunma 1 were significanlty up- or down-regulated than those in Inner Mongolia Xiaolidama under cadmium stress, indicating that these GRAS genes were significantly related to cadmium stress. This study can provide a reference for subsequent mining and verification of GRAS genes in hemp.