Molecular characterization of the allelic variation at the VRN-H2 vernalization locus in barley

Dubcovsky, Jorge; Chen, Chialing; Yan, Liuling

doi:10.1007/s11032-005-0084-6

Cited by 107 publications

(90 citation statements)

References 18 publications

(44 reference statements)

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“…In winter wheat and barley, loss-of-function mutations in VRN2 are associated with early flowering, and silencing of VRN2 reduces heading time (Yan et al, 2004a;Dubcovsky et al, 2005). Similarly, we found that B. distachyon Bd21-3 amiVRN2 knockdown and BdVRN2-overexpressing lines flower significantly earlier and later than the wild type, respectively.…”

Section: Conservation Of Vrn2 As a Flowering Repressorsupporting

confidence: 65%

“…A second piece of evidence supporting the absence of cold and VRN1-mediated regulation of VRN2 outside core Pooideae comes from gene expression analyses. Rather than decreasing in response to cold, as in winter wheat, barley, and oat (Yan et al, 2004a;Dubcovsky et al, 2005;von Zitzewitz et al, 2005;Distelfeld et al, 2009b) (Fig. 2), VRN2 expression actually increases transiently in B. distachyon Bd21-3 or is unaffected by cold in vernalization-responsive M. nutans and N. pulchra.…”

Section: Co-option Of Vrn2 In Core Pooid Vernalization Responsivenessmentioning

confidence: 87%

“…Although vernalization alleviates FT repression, FT also requires long days to become activated; thus, flowering only occurs during the lengthening days of spring and summer (Yan et al, 2006;Hemming et al, 2008;Sasani et al, 2009). In wheat and barley, VRN2 is necessary for the vernalization requirement because deletions of the entire locus or point mutations in the CCT domain result in spring varieties, which do not require vernalization (Yan et al, 2004;Dubcovsky et al, 2005;Karsai et al, 2005;von Zitzewitz et al, 2005;Distelfeld et al, 2009b).…”

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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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Section: Conservation Of Vrn2 As a Flowering Repressorsupporting

confidence: 65%

Section: Co-option Of Vrn2 In Core Pooid Vernalization Responsivenessmentioning

confidence: 87%

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confidence: 99%

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

et al. 2016

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“…Epistatic relationships between VRN1, VRN2, and FT in leaves have been revealed through the study of existing allelic variants (Trevaskis et al, 2003;Yan et al, 2003Yan et al, , 2004bYan et al, , 2006Dubcovsky et al, 2005;Karsai et al, 2005;Hemming et al, 2008;Shimada et al, 2009). Particular varieties of spring barley and spring wheat, which do not require vernalization, carry either deletions of the VRN2 locus or point mutations in the CCT domain of VRN2 (Yan et al, 2004b;Dubcovsky et al, 2005;Karsai et al, 2005;von Zitzewitz et al, 2005;Distelfeld et al, 2009b).…”

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confidence: 99%

Interaction of Photoperiod and Vernalization Determines Flowering Time of Brachypodium distachyon

et al. 2013

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Timing of flowering is key to the reproductive success of many plants. In temperate climates, flowering is often coordinated with seasonal environmental cues such as temperature and photoperiod. Vernalization is an example of temperature influencing the timing of flowering and is defined as the process by which a prolonged exposure to the cold of winter results in competence to flower during the following spring. In cereals, three genes (VERNALIZATION1 [VRN1], VRN2, and FLOWERING LOCUS T [FT]) have been identified that influence the vernalization requirement and are thought to form a regulatory loop to control the timing of flowering. Here, we characterize natural variation in the vernalization and photoperiod responses in Brachypodium distachyon, a small temperate grass related to wheat (Triticum aestivum) and barley (Hordeum vulgare). Brachypodium spp. accessions display a wide range of flowering responses to different photoperiods and lengths of vernalization. In addition, we characterize the expression patterns of the closest homologs of VRN1, VRN2 (VRN2-like [BdVRN2L]), and FT before, during, and after cold exposure as well as in different photoperiods. FT messenger RNA levels generally correlate with flowering time among accessions grown in different photoperiods, and FT is more highly expressed in vernalized plants after cold. VRN1 is induced by cold in leaves and remains high following vernalization. Plants overexpressing VRN1 or FT flower rapidly in the absence of vernalization, and plants overexpressing VRN1 exhibit lower BdVRN2L levels. Interestingly, BdVRN2L is induced during cold, which is a difference in the behavior of BdVRN2L compared with wheat VRN2 during cold.

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“…However, for simplicity, we will refer to these genes as VRN1 hereafter. VRN2 is encoded by a zinc-finger-CCT domain transcription factor (ZCCT1; Yan et al, 2004b;Dubcovsky et al, 2005;Karsai et al, 2005;Szü cs et al, 2006b).…”

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confidence: 99%

Discrete Developmental Roles for Temperate Cereal GrassVERNALIZATION1/FRUITFULL-Like Genes in Flowering Competency and the Transition to Flowering

Preston

Kellogg

2007

Plant Physiology

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Members of the grass subfamily Pooideae are characterized by their adaptation to cool temperate climates. Vernalization is the process whereby flowering is accelerated in response to a prolonged period of cold. Winter cereals are tolerant of low temperatures and flower earlier with vernalization, whereas spring cultivars are intolerant of low temperatures and flower later with vernalization. In the pooid grasses wheat (Triticum monococcum, Triticum aestivum) and barley (Hordeum vulgare), vernalization responsiveness is determined by allelic variation at the VERNALIZATION1 (VRN1) and/or VRN2 loci. To determine whether VRN1, and its paralog FRUITFULL2 (FUL2), are involved in vernalization requirement across Pooideae, we determined expression profiles for multiple cultivars of oat (Avena sativa) and wheat with and without cold treatment. Our results demonstrate significant up-regulation of VRN1 expression in leaves of winter oat and wheat in response to vernalization; no treatment effect was found for spring or facultative growth habit oat and wheat. Similar cold-dependent patterns of leaf expression were found for FUL2 in winter oat, but not winter wheat, suggesting a redundant qualitative role for these genes in the quantitative induction of flowering competency of oat. These and other data support the hypothesis that VRN1 is a common regulator of vernalization responsiveness within the crown pooids. Finally, we found that up-regulation of VRN1 in vegetative meristems of oat was significantly later than in leaves. This suggests distinct and conserved roles for temperate cereal grass VRN1/FUL-like genes, first, in systemic signaling to induce flowering competency, and second, in meristems to activate genes involved in the floral transition.

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Molecular characterization of the allelic variation at the VRN-H2 vernalization locus in barley

Cited by 107 publications

References 18 publications

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

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

Interaction of Photoperiod and Vernalization Determines Flowering Time of Brachypodium distachyon

Discrete Developmental Roles for Temperate Cereal GrassVERNALIZATION1/FRUITFULL-Like Genes in Flowering Competency and the Transition to Flowering

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