Genome-wide analysis of BURP domain-containing genes in maize and sorghum

BURP domain-containing genes comprise a large plant-specific family, yet the functions are very poorly understood, especially in maize (Zea mays) and sorghum (Sorghum vulgare). In this study, 26 BURP family genes in maize (ZmBURP01-15) and sorghum (SbBURP01-11) were identified including the gene structure, phylogenetic relationship, conserved protein motifs and chromosome locations. These genes have diverse exon-intron structures and distinct organization of putative motifs. The distributions of the genes vary: 15 ZmBURP genes are located in maize on five chromosomes, and 11 SbBURP genes in sorghum are on six chromosomes. Based on the phylogenetic analysis of BURP protein sequences from maize, sorghum and other plants, the BURP genes in maize and sorghum were categorized into five subfamilies (RD22-like, PG1β-like, BURP VI, BURP VII and BURP VIII). Transcript level analysis of ZmBURP genes revealed the expression patterns of BURP genes in maize under diffferent stress conditions. The results suggested that only eight ZmBURP genes were responsive to at least one of the stress treatments applied. Among these genes, seven genes (ZmBURP04, ZmBURP05, ZmBURP08, ZmBURP09, ZmBURP12, ZmBURP14, ZmBURP15) were responsive to ABA and cold respectively, two genes (ZmBURP06 and ZmBURP14) were responsive to NaCl. The results presented here provide useful information for further functional analysis of the BURP gene family in maize and sorghum.