Genome-wide analysis of maize CONSTANS-LIKE gene family and expression profiling under light/dark and abscisic acid treatment

The CONSTANS-LIKE (COL) gene has an important role both in regulation flowering through photoperiodic control and response to abiotic stress. In the present study, we performed a genome-wide analysis of maize COL gene family and identified 19 non-redundant ZmCOL genes, which were unequally distributed on ten maize chromosomes. Analysis of compound phylogenetic tree (maize, sorghum, rice and Arabidopsis) showed high bootstrap, as well as conserved domain and semblable gene structures among members within the same clade, revealing that COL genes in same clade were from the common ancestral and prior to the divergence of monocots and dicots lineages. Calculation of Ka/Ks ratio demonstrated that most duplicated ZmCOLs experienced purifying selection, which suggested limited functional divergence after duplication events. Comparing interspecies gene collinearity between three major grasses species, extensive microsynteny was detected among maize, sorghum and rice COL-containing segments. Additionally, several light-responsive and one ABA-responsive cis-elements could be detected for ZmCOL genes in group A. Therefore, qRT-PCR was performed to explore the expression patterns of ZmCOL genes in group A under light/dark conditions and ABA treatment. Our results laid the foundation for functional characterization of ZmCOL proteins and uncovering the biological roles of COL genes in response to stress in future.