The role of seasonal flowering responses in adaptation of grasses to temperate climates

Fjellheim, Siri; Boden, Scott A.; Trevaskis, Ben

doi:10.3389/fpls.2014.00431

Cited by 89 publications

(82 citation statements)

References 149 publications

(203 reference statements)

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“…It decreases when several environments and/or years are taken into account and also, as expected, when reproductive and vegetative growing stages are included: 0.3-0.6 [38,[40][41][42][43]. Differences in vernalization requirements between genotypes exist in perennial grasses [44][45][46] and could lead to differences in the date of flower induction, which in turn could lead to differences in leaf length. These differences in leaf length between genotypes do not reflect true differences in leaf length potential but rather differences in earliness of flower induction.…”

Section: Heritabilitymentioning

confidence: 64%

Leaf Length Variation in Perennial Forage Grasses

2015

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Leaf length is a key factor in the economic value of different grass species and cultivars in forage production. It is also important for the survival of individual plants within a sward. The objective of this paper is to discuss the basis of within-species variation in leaf length. Selection for leaf length has been highly efficient, with moderate to high narrow sense heritability. Nevertheless, the genetic regulation of leaf length is complex because it involves many genes with small individual effects. This could explain the low stability of QTL found in different studies. Leaf length has a strong response to environmental conditions. However, when significant genotype × environment interactions have been identified, their effects have been smaller than the main effects. Recent modelling-based research suggests that many of the reported environmental effects on leaf length and genotype × environment interactions could be biased. Indeed, it has been shown that leaf length is an emergent property strongly affected by the architectural state of the plant during significant periods prior to leaf emergence. This approach could lead to improved understanding of the factors affecting leaf length, as well as better estimates of the main genetic effects.

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Section: Heritabilitymentioning

confidence: 64%

Leaf Length Variation in Perennial Forage Grasses

2015

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“…It is hypothesized that vernalization responsiveness evolved early during the diversification of Pooideae, as a key adaptation allowing for their transition into the temperate zone (Preston and Sandve, 2013;Fjellheim et al, 2014). Within core Pooideae, many species have been characterized as vernalization responsive (Heide, 1994;Grass Phylogeny Working Group, 2001;Grass Phylogeny Working Group II, 2012).…”

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confidence: 99%

Evolution of VRN2/Ghd7-Like Genes in Vernalization-Mediated Repression of Grass Flowering

et al. 2016

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Flowering of many plant species is coordinated with seasonal environmental cues such as temperature and photoperiod. Vernalization provides competence to flower after prolonged cold exposure, and a vernalization requirement prevents flowering from occurring prior to winter. In winter wheat (Triticum aestivum) and barley (Hordeum vulgare), three genes VRN1, VRN2, and FT form a regulatory loop that regulates the initiation of flowering. Prior to cold exposure, VRN2 represses FT. During cold, VRN1 expression increases, resulting in the repression of VRN2, which in turn allows activation of FT during long days to induce flowering. Here, we test whether the circuitry of this regulatory loop is conserved across Pooideae, consistent with their niche transition from the tropics to the temperate zone. Our phylogenetic analyses of VRN2-like genes reveal a duplication event occurred before the diversification of the grasses that gave rise to a CO9 and VRN2/Ghd7 clade and support orthology between wheat/barley VRN2 and rice (Oryza sativa) Ghd7. Our Brachypodium distachyon VRN1 and VRN2 knockdown and overexpression experiments demonstrate functional conservation of grass VRN1 and VRN2 in the promotion and repression of flowering, respectively. However, expression analyses in a range of pooids demonstrate that the cold repression of VRN2 is unique to core Pooideae such as wheat and barley. Furthermore, VRN1 knockdown in B. distachyon demonstrates that the VRN1-mediated suppression of VRN2 is not conserved. Thus, the VRN1-VRN2 feature of the regulatory loop appears to have evolved late in the diversification of temperate grasses.The initiation of flowering is a major developmental transition in the plant life cycle. When flowering initiates, shoot apical meristems shift from forming vegetative organs such as leaves to forming flowers. In many plant species, flowering occurs at a particular time of year in response to the sensing of seasonal cues such as changes in day length and temperature. In some plants adapted to temperate climates, exposure to the prolonged cold of winter (vernalization) results in the ability to flower in the next growing season (Chouard, 1960;Amasino, 2010). Although vernalization ultimately enables flowering, vernalization responsiveness is typically an adaptation to ensure that flowering does not occur prematurely in the fall season. This has obvious adaptive value; for example, many vernalization-responsive plants become established in the fall season (during which flowering would not lead to successful reproduction) and then rapidly flower in the spring when conditions for reproduction and seed maturation are optimal.The grass family (Poaceae) originated approximately 70 million years ago as part of the tropical forest understory. However, grasses have since diversified across the globe occupying a variety of ecological niches (Kellogg, 2001). Exemplifying this, the ;3,800 species of grass subfamily Pooideae, including the economically important cereals wheat (Triticum aestivum, Triticeae), barley (...

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“…In "winter" annuals and perennials, the flowering transition is induced by an extended period of cold that results in a physiological switch allowing plants to flower when secondarily induced by specific day lengths and/or warm temperatures. Rapid flowering following exposure to cold temperatures is termed vernalization responsiveness (Chouard, 1960) and is postulated to be an evolutionary strategy to ready temperate plants for spring flowering (Wollenberg and Amasino, 2012;Preston and Sandve, 2013;Fjellheim et al, 2014). However, in regions experiencing little cold or temperature seasonality, a response to vernalization can substantially delay flowering, resulting in reduced fitness.…”

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confidence: 99%

Evidence for an Early Origin of Vernalization Responsiveness in Temperate Pooideae Grasses

et al. 2016

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The ability of plants to match their reproductive output with favorable environmental conditions has major consequences both for lifetime fitness and geographic patterns of diversity. In temperate ecosystems, some plant species have evolved the ability to use winter nonfreezing cold (vernalization) as a cue to ready them for spring flowering. However, it is unknown how important the evolution of vernalization responsiveness has been for the colonization and subsequent diversification of taxa within the northern and southern temperate zones. Grasses of subfamily Pooideae, including several important crops, such as wheat (Triticum aestivum), barley (Hordeum vulgare), and oats (Avena sativa), predominate in the northern temperate zone, and it is hypothesized that their radiation was facilitated by the early evolution of vernalization responsiveness. Predictions of this early origin hypothesis are that a response to vernalization is widespread within the subfamily and that the genetic basis of this trait is conserved. To test these predictions, we determined and reconstructed vernalization responsiveness across Pooideae and compared expression of wheat vernalization gene orthologs VERNALIZATION1 (VRN1) and VRN3 in phylogenetically representative taxa under cold and control conditions. Our results demonstrate that vernalization responsive Pooideae species are widespread, suggesting that this trait evolved early in the lineage and that at least part of the vernalization gene network is conserved throughout the subfamily. These results are consistent with the hypothesis that the evolution of vernalization responsiveness was important for the initial transition of Pooideae out of the tropics and into the temperate zone.

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The role of seasonal flowering responses in adaptation of grasses to temperate climates

Cited by 89 publications

References 149 publications

Leaf Length Variation in Perennial Forage Grasses

Leaf Length Variation in Perennial Forage Grasses

Evolution of VRN2/Ghd7-Like Genes in Vernalization-Mediated Repression of Grass Flowering

Evidence for an Early Origin of Vernalization Responsiveness in Temperate Pooideae Grasses

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