Identification and Characterization of Perennial Ryegrass (Lolium perenne) Vernalization Genes

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.

Functional contribution of two perennial grasses to enhance pasture production and drought resistance under a leaf regrowth stage defoliation criterion

“…Stem elongation marks the maximum growth rate in the growing season (Parsons, 1988), and cv. Trojan (classified as late heading time by Herridge et al (2021)) produced a concentrated flowering in mid‐December, whereas Bv started flowering in early November and continued up until early January (data not shown).…”

Late‐heading parental selection in orchardgrass (Dactylis glomerata L.)

“…families for the cool-season forage grass perennial ryegrass (Lolium perenne L.) (Herridge et al, 2021). The status of these candidate genes in breeding populations of orchardgrass is unknown.…”

“…In orchardgrass, tremendous variation in HD has been reported (Zhao et al., 2017), and heritabilities have ranged from h 2 = 0.51 to h 2 = 0.89 (Jafari & Naseri, 2007; Majidi et al., 2015). The genetic mechanisms of HD can be separated into vernalization and photoperiod effectors (Fjellheim et al., 2014), with the vernalization response in particular mediated by VRN1, VRN2, and VRN3/FT1 genes (Faure et al., 2007; Herridge et al., 2021; Jack, 2004; Skøt et al., 2007). Many previous studies identified these three VRN genes as quantitative trait loci (QTL) or otherwise candidates for forage grass HD (Herridge et al., 2021; Jokela et al., 2015; Nuñez & Yamada, 2017; Schwartz et al., 2010; Skøt et al., 2007).…”

“…The genetic mechanisms of HD can be separated into vernalization and photoperiod effectors (Fjellheim et al., 2014), with the vernalization response in particular mediated by VRN1, VRN2, and VRN3/FT1 genes (Faure et al., 2007; Herridge et al., 2021; Jack, 2004; Skøt et al., 2007). Many previous studies identified these three VRN genes as quantitative trait loci (QTL) or otherwise candidates for forage grass HD (Herridge et al., 2021; Jokela et al., 2015; Nuñez & Yamada, 2017; Schwartz et al., 2010; Skøt et al., 2007). The VRN1 gene expression is induced through vernalization and enters a positive feedback loop with FT1 to induce flowering upon long days (Distelfeld et al., 2009; Trevaskis, 2010).…”

Bioaerosols and atmospheric ice nuclei in a Mediterranean dryland: community changes related to rainfall

“…The allergen Lol p 1 was found in all samples, except CY19. Lol p 1 is the major allergen of the perennial ryegrass (Lolium perenne, Poaceae), which is common in Cyprus and flowers in springtime (Gucel et al, 2013;Herridge et al, 2021), which was the period of sampling. The Bet v 1 type allergens can be found in members of various plant families such as Betulaceae, Fabaceae, and Rosaceae, which are all common in Cyprus.…”