Genome-wide analysis of maize MBD gene family and expression profiling under abiotic stress treatment at the seedling stage

Abstract

Methyl-CpG-binding domain (MBD) proteins in plants are important trans-acting factors specifically recognizing methylated DNA. The MBD proteins can compact chromatins to repress transcription by recruiting chromatin-modifying complexes that contain histone deacetylase activities and chromatin remodeling factors, and play a crucial biological role in the growth and development in plants. Currently, very little is known regarding the structure and function of MBD genes in plants. In this study, we performed a genome-wide identification and expression profile analysis of maize MBD genes (ZmMBDs) from the latest version of the maize (B73) genome. By analyzing phylogenetic relationship of MBD gene families from Arabidopsis, rice, wheat, and maize, all 14 MBD proteins in maize were categorized into four subclasses. Furthermore, chromosome location and schematic structure revealed an unevenly distribution on chromosomes and structure features of MBD genes in maize, respectively. Eventually, EST expression data mining, microarray data clustering analysis, and semi-quantitative and quantitative expression profile analyses detected in seedling leaves and stems by heat, drought, and salt-stress treatments have demonstrated that these genes had temporal and spatial expression pattern and exhibited different expression levels under heat, drought, and salt-stress conditions, suggesting that functional diversification of the MBD gene family in maize. In addition, through electrophoretic mobility shift assay (EMSA) a representative MBD protein, ZmMBD11, exhibited in vitro DNA-binding activity, indicating that that the MBD proteins in maize might play a role in reading cytosine methylation. Taken together, these results would provide an important theoretical basis for future functional verification of ZmMBD genes and also facilitate future experimental research to further unravel the mechanisms of epigenetic regulation in plants.