Genome-Wide Identification of Flowering-Time Genes in Species and Reveals a Correlation between Selective Pressure and Expression Patterns of Vernalization-Pathway Genes in .

Flowering time is a key agronomic trait, directly influencing crop yield and quality. Many flowering-time genes have been identified and characterized in the model plant ; however, these genes remain uncharacterized in many agronomically important crops. In this study, we identified 1064, 510, and 524 putative orthologs of flowering-time genes from , and , respectively, and found that genes involved in the aging and ambient temperature pathways were fewer than those in other flowering pathways. Flowering-time genes were distributed mostly on chromosome C03 in and , and on chromosome A09 in . Calculation of non-synonymous ()/synonymous substitution () ratios suggested that flowering-time genes in vernalization pathways experienced higher selection pressure than those in other pathways. Expression analysis showed that most vernalization-pathway genes were expressed in flowering organs. Approximately 40% of these genes were highly expressed in the anther, whereas flowering-time integrator genes were expressed in a highly organ-specific manner. Evolutionary selection pressures were negatively correlated with the breadth and expression levels of vernalization-pathway genes. These findings provide an integrated framework of flowering-time genes in these three crops and provide a foundation for deciphering the relationship between gene expression patterns and their evolutionary selection pressures in .