Genome-wide identification,characterization, and expression profiles of auxin responsive GH3 gene family in Salvia miltiorrhiza involved in MeJA treatment

GH3 (Gretchen Hagen 3) is a gene family involved in the response to auxin and plays a role in regulation of plant growth, development and stress responses. The GH3 gene family has been well investigated in genome wide in various plants containing Arabidopsis, rice, maize, etc. However, the study on the GH3 family and its roles involved in JA-signal pathway in Salvia miltiorrhiza is lacking. In this study, we performed a systematic identification of the SmGH3 gene family in genome wide and detected 11 members on 8 S. miltiorrhiza scaffolds. Phylogenetic analyses revealed that SmGH3 proteins could be clustered in two major categories with groups 1 and 2 of GH3 family of Arabidopsis. Diversified cis-elements in the promoter of SmGH3 were predicted as essential players in regulating SmGH3 expression patterns by using PlantCARE database. Gene structure and motif analyses indicated that most SmGH3 genes had relatively conserved exon/intron arrangements and motif compositions. RNA-seq analysis and RT-qPCR showed that 3 SmGH3s (SmGH3.2, SmGH3.6, and SmGH3.10) were up-regulated in S. miltiorrhiza treated by MeJA. Moreover, tissue-specific expression patterns of each SmGH3 genes in different tissues suggested that the various members of GH3 genes conducted their role in the different tissues of S. miltiorrhiza. These results would provide a comprehensive understanding of the GH3 gene family in S. miltiorrhiza and lay a foundation for exploration of their functional divergence and genetic manipulation.