Global dissection of the BAHD acyltransferase gene family in soybean: Expression profiling, metabolic functions, and evolution
Abstract Background: Members of the BAHD acyltransferase (ACT) family play important roles in plant defence against biotic and abiotic stresses. A better understanding of the functions that specific members of this family play in stress defence can lead to better breeding strategies for stress tolerance. Previous genome-wide studies explored other acyltransferase families, but so far not a single study has been published on genome-wide or positive selection analyses of the BAHD genes in Glycine max . Results: A total of 103 genes of the BAHD family (GmACT genes) were identified from the soybean genome, which could be grouped into four phylogenetic clades (I-IV). Clade III was further divided into two sub-clades (IIIA and IIIB). In each clade, the gene structure and functional motifs were relatively well conserved. These ACT genes were unequally distributed on all 20 chromosomes, and 16 paralogous pairs were found within the family. Positive selection analysis revealed amino acids under strong positive selection, which suggests that the evolution of this gene family modulated soybean domestication. Some GmACT genes showed expression specific under specific conditions, while others showed constitutive expression in all soybean tissues or conditions analysed. Most of the expression of ACT genes in soybean was repressed with Al 3+ and fungal elicitor exposure, except for GmACT84 , which expression increased in these conditions 2- and 3-fold, respectively. The promoter of GmACT84 contains the maximum number of stress-responsive elements among all GmACT genes and it is especially enriched in MYB-related elements. Conclusions: This study provides a genome-wide analysis of the BAHD gene family and assessed their expression profiles in soybean. We found evidence of a strong positive selection of GmACT genes. Our findings will help efforts of functional characterisation of ACT genes in soybean in order to discover their involvement in growth, development, and defence mechanisms.