Abstract

Flowering is an important phase in the angiosperms life cycle, as it signifies the transition from vegetative to reproductive phase. Recently, increasing number of flowering genes are being cloned and analyzed. However, few studies have focused on the comparative analysis of key candidate genes involved in the regulation of flowering time across species. We explore the common characteristics of key flowering genes across species and compare their diversity and evolutionary divergence. We analyze key flowering candidate genes in three species, Arabidopsis thaliana, Oryza sativa and Zea mays. The homology of flowering genes across the three species was more than 60%. Nucleotide polymorphism analysis for these genes revealed high sequence conservation during evolution, although some small insertion/deletions (InDels) were also detected. Furthermore, these candidate genes harbored simple repeat sequence repeats that perhaps drove genetic variation and divergence of these genes. The flowering genes were expressed preferentially in the organelle and cellular components and participated mainly in metabolic processes with binding and catalytic functionality. These results suggested that key flowering genes have more common characteristics that may allow the identification and analysis of other flowering genes, especially in species where genome sequencing has not yet been performed.

Key words: Evolution, flowering gene, simple repeat sequences, homologous genes.

Abbreviation

FCA, Flowering locus CA; DTH8, days to heading on chromosome 8;CO, constans; FLC, flowering locus C; SOC1, suppressor of overexpression of CO 1; FT, flowering locus T; Ehd1, early heading date 1; GI, gigantea; Hd3a, heading date 3a; FKF1, flavin-binding kelch repeat; DnaSP, DNA sequence polymorphism analysis; InDel, insertion/deletion; GO DAG, go directed acyclic graph.