Identification and Characterization of Perennial Ryegrass () Vernalization Genes.

Perennial ryegrass () is a temperate grass species commonly used as pasture for livestock. Flowering (heading) of ryegrass impacts metabolizable energy content and seed yield, therefore this trait is important for both farmers and seed producers. In related grass species, the genes (-) have been largely implicated in the determination of vernalization response and are responsible for much of the intra-species variation in this trait. Many other important flowering-time regulators have been cataloged in the model grass however, in several cases, such as , their ryegrass homologs have not been well-characterized. Here, ryegrass homologs of important flowering time genes from were identified through available synteny data and sequence similarity. Phylogenetic analysis of and genes was performed to elucidate these families further. The expression patterns of these genes were assessed during vernalization. This confirmed the key roles played by and in the promotion of flowering. Furthermore, two orthologs of identified here, as well as an ortholog of , were expressed prior to vernalization, and were repressed in flowering plants, suggesting a role in floral repression. Significant variability in expression of these flowering pathway genes in diverse genotypes was detected and may underlie variation in flowering time and vernalization response.