Molecular Evolution and Genetic Variation of G2-Like Transcription Factor Genes in Maize

The productivity of maize (Zea mays L.) depends on the development of chloroplasts, and G2-like transcription factors play a central role in regulating chloroplast development. In this study, we identified 59 G2-like genes in the B73 maize genome and systematically analyzed these genes at the molecular and evolutionary levels. Based on gene structure character, motif compositions and phylogenetic analysis, maize G2-like genes (ZmG1-ZmG59) were divided into seven groups (I-VII). By synteny analysis, 18 collinear gene pairs and strongly conserved microsyntny among regions hosting G2-like genes across maize and sorghum were found. Here, we showed that the vast majority of ZmG gene duplications resulted from whole genome duplication events rather than tandem duplications. After gene duplication events, some ZmG genes were silenced. The functions of G2-like genes were multifarious and most genes that are expressed in green tissues may relate to maize photosynthesis. The qRT-PCR showed that the expression of these genes was sensitive to low temperature and drought. Furthermore, we analyzed differences of ZmGs specific to cultivars in temperate and tropical regions at the population level. Interestingly, the single nucleotide polymorphism (SNP) analysis revealed that nucleotide polymorphism associated with different temperature zones. Above all, G2-like genes were highly conserved during evolution, but polymorphism could be caused due to a different geographical location. Moreover, G2-like genes might be related to cold and drought stresses.