Abstract
Perennial ryegrass (
Lolium perenne
) 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
VRN
genes (
VRN1
-
3
) 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
Brachypodium distachyon;
however, in several cases, such as
VRN2
, their ryegrass homologs have not been well-characterized. Here, ryegrass homologs of important flowering time genes from
B. distachyon
were identified through available synteny data and sequence similarity. Phylogenetic analysis of
VRN3/FT-like
and
VRN2-like
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
LpVRN1
and
LpFT3
in the promotion of flowering. Furthermore, two orthologs of
VRN2
identified here, as well as an ortholog of
CO9
, 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.