Genome-wide identification and expression profile analysis of the HOG gene family in Aspergillus oryzae

The High osmolarity glycerol (HOG) gene family plays crucial roles in various developmental and physiological processes in fungi, such as the permeability of cell membrane, chlamydospore formation and stress signaling. Although the function of HOG genes has been investigated in Saccharomyces cerevisiae and some filamentous fungi, a comprehensive analysis of HOG gene family has not been performed in Aspergillus oryzae, a fungi mainly used for the production of soy sauce. In this study, we identified and corrected a total of 90 HOG genes from the A. oryzae genome. According to the phylogenetic relationship, they were divided into four discrete groups (Group A–D) comprising of 16, 24, 30 and 20 proteins, respectively. Six conserved motifs and exon–intron structures were examined among all HOG proteins to reveal the diversity of AoHOG genes. Based on transcriptome technology, the expression patterns of AoHOG genes across all developmental stages was identified, suggesting that the AoHOG gene family mainly functions in the logarithmic phase of development. The expression profiles of AoHOG genes under different concentrations of salt stress indicated that AoHOG genes are extensively involved in salt stress response, with possibly different mechanisms. The genome-wide identification, evolutionary, gene structures and expression analyses of AoHOG genes provide a comprehensive overview of this gene family as well as their potential involvements in development and stress responses. Our results will facilitate further research on HOG gene family regarding their physiological and biochemical functions.