The <i>cycloidea</i> gene can respond to a common dorsoventral prepattern in <i>Antirrhinum</i>

Clark, Jennifer I.; Coen, Enrico

doi:10.1046/j.1365-313x.2002.01310.x

Cited by 45 publications

(39 citation statements)

References 43 publications

(46 reference statements)

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“…To test whether gain of CYC might lead to a corresponding increase of RAD expression, RNA in situ experiments were carried out on the backpetals mutant cyc-705. This allele confers a dorsalized phenotype and carries a transposon insertion in the CYC promoter that results in ectopic expression of CYC in the lateral and ventral petals after about stage six (7,25). RAD was also ectopically expressed in lateral and ventral petals of the backpetals mutant, mirroring the ectopic pattern of CYC expression (Fig.…”

Section: Expression Of Rad In Floral Symmetrymentioning

confidence: 95%

“…Also, both genes were expressed in the staminode; although, within the staminode, the CYC and RAD expression domains seemed almost complementary: CYC was expressed throughout the staminode, except for a small patch on the abaxial side, whereas RAD expression appeared to be strongest on the abaxial side ( Fig. 5 e and f ) (25).…”

Section: Rad Mutant Phenotypes and Interactionsmentioning

confidence: 96%

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Floral asymmetry involves an interplay between TCP and MYB transcription factors in Antirrhinum

Corley

Carpenter

Copsey

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

221

276

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To understand how genes control floral asymmetry, we have isolated and analyzed the role of the RADIALIS (RAD) gene in Antirrhinum. We show that the RAD gene encodes a small MYB-like protein that is specifically expressed in the dorsal region of developing flowers. RAD has a single MYB-like domain that is closely related to one of the two MYB-like domains of DIV, a protein that has an antagonistic effect to RAD on floral development. Interactions between RAD and other genes indicate that floral asymmetry depends on the interplay between two pairs of transcription factors. First, a pair of TCP proteins is expressed in dorsal regions of the floral meristem, leading to the activation of RAD in the dorsal domain. The RAD MYB-like protein then antagonizes the related DIV MYB-like protein, preventing DIV activity in dorsal regions. In addition to its role in dorsal regions, RAD acts nonautonomously on lateral regions either directly, through RAD protein movement, or indirectly, through a signaling molecule.F loral asymmetry is thought to have evolved many times independently as a specialized mechanism for pollinator interaction (1-3). In a few cases, most notably in Antirrhinum majus, the molecular genetic basis of floral asymmetry has begun to be understood. Four key genes have been shown to control dorsoventral asymmetry in Antirrhinum: CYCLOIDEA (CYC), DICHOTOMA (DICH), RADIALIS (RAD), and DIVARICATA (DIV) (4-8). Two of these genes, CYC and DICH, promote dorsal identity and encode proteins belonging to the TCP family of transcription factors. DIV promotes ventral identity and encodes a protein belonging to the MYB family of transcription factors, carrying two MYB-like domains. However, the mechanism by which CYC, DICH, and DIV interact remains unclear. To address this question, we have isolated and characterized RAD, the fourth member of this group of genes, and explored how it acts in combination with the other genes to establish floral asymmetry.Flowers of wild-type Antirrhinum are zygomorphic, having a single plane of symmetry (bilateral symmetry), in contrast to actinomorphic flowers, which have multiple planes of symmetry (radial symmetry) (3). The zygomorphy of Antirrhinum flowers reflects morphological distinctions between the upper (dorsal) and lower (lateral and ventral) organs of whorls two and three. In whorl two, each flower has two dorsal petals, two lateral petals, and one ventral petal, whereas whorl three comprises a single arrested dorsal stamen (staminode), two lateral stamens, and two ventral stamens (Fig. 1 a and b).The CYC and DICH genes are required for dorsoventral asymmetry in Antirrhinum and are expressed from an early stage in the dorsal domain of the floral meristem (5, 7, 9). At later stages, CYC expression persists throughout most of the dorsal domain, whereas DICH becomes restricted to the most dorsal half of the dorsal domain. Inactivation of both CYC and DICH results in peloric (radially symmetrical) flowers, in which all petals have ventral identity (Fig. 1h). In cyc or dich single ...

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Section: Expression Of Rad In Floral Symmetrymentioning

confidence: 95%

Section: Rad Mutant Phenotypes and Interactionsmentioning

confidence: 96%

Floral asymmetry involves an interplay between TCP and MYB transcription factors in Antirrhinum

Corley

Carpenter

Copsey

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

221

276

View full text Add to dashboard Cite

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“…CYC-like genes have been co-opted into at least two separate genetic programs promoting floral asymmetry in angiosperms, once within the asterids (Antirrhinum and relatives), and once within the rosids (Lotus and other legumes) (Cubas 2004). CYC-like genes are expressed in a generalized dorsoventral pre-pattern in meristems involved in both flower and shoot formation, even in species with actinomorphic flowers, suggesting that the origin of the genes predates their role in zygomorphy (Cubas et al 2001;Clark and Coen 2002). However, it is only in zygomorphic species that CYC-like gene expression is maintained during flower development in dorsal floral organs (Luo et al 1996;Luo et al 1999;Cubas et al 1999b;Feng et al 2006;Citerne et al 2006;Wang et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…However, it is only in zygomorphic species that CYC-like gene expression is maintained during flower development in dorsal floral organs (Luo et al 1996;Luo et al 1999;Cubas et al 1999b;Feng et al 2006;Citerne et al 2006;Wang et al 2008). This acquisition and maintenance of CYC expression in dorsal floral organs may have been the driving force behind the evolution of dorsoventral floral asymmetry (Clark and Coen 2002). Changes in the regulation of CYC-like genes have also played a causal role in the evolution of derived zygomorphic variants within the Antirrhineae.…”

Section: Introductionmentioning

confidence: 99%

Evolution of flower shape in Plantago lanceolata

et al. 2009

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Plantago lanceolata produces small actinomorphic (radially symmetric), wind-pollinated flowers that have evolved from a zygomorphic, biotically pollinated ancestral state. To understand the developmental mechanisms that might underlie this change in flower shape, and associated change in pollination syndrome, we analyzed the role of CYC-like genes in P. lanceolata. Related zygomorphic species have two CYC-like genes that are expressed asymmetrically in the dorsal region of young floral meristems and in developing flowers, where they affect the rate of development of dorsal petals and stamens. Plantago has a single CYC-like gene (PlCYC) that is not expressed in early floral meristems and there is no apparent asymmetry in the pattern of PlCYC expression during later flower development. Thus, the evolution of actinomorphy in Plantago correlates with loss of dorsal-specific CYC-like gene function. PlCYC is expressed in the inflorescence stem, in pedicels, and relatively late in stamen development, suggesting a novel role for PlCYC in compacting the inflorescence and retarding stamen elongation in this wind pollinated species.

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“…These secondary inflorescence meristems do themselves produce bracts that will in turn subtend tertiary inflorescence meristems. Despite their inflorescence identities, these secondary and tertiary meristems express CYC in domains that are always located dorsally relative to the meristems from which they originated (Clark and Coen, 2002). Thus, dorsal-specific expression of CYC can be established independently of floral identity.…”

Section: Cyc /Dich In Species Other Than Antirrhinummentioning

confidence: 99%

Flower symmetry and shape in Antirrhinum

Almeida¹,

Galego²

2005

Int. J. Dev. Biol.

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According to their symmetry, flowers are classified as radially symmetrical or bilaterally symmetrical. Bilateral symmetry, which is thought to have evolved from radial symmetry, results from establishment of asymmetry relative to a dorsoventral axis of flowers. Here we consider developmental genetic mechanisms underlying the generation of this asymmetry and how they relate to controls of petal shape and growth in Antirrhinum. Two genes, CYC and DICH, are expressed in dorsal domains of the Antirrhinum flower and determine its overall dorsoventral asymmetry and the asymmetries and shapes of individual floral organs, by influencing regional growth. Another gene, DIV, influences regional asymmetries and shapes in ventral regions of the flower through a quantitative effect on growth. However, DIV is not involved in determining the overall dorsoventral asymmetry of the flower and its effects on regional asymmetries depend on interactions with CYC/DICH. These interactions illustrate how gene activity, symmetry, shape and growth may be related.

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The cycloidea gene can respond to a common dorsoventral prepattern in Antirrhinum

Cited by 45 publications

References 43 publications

Floral asymmetry involves an interplay between TCP and MYB transcription factors in Antirrhinum

Floral asymmetry involves an interplay between TCP and MYB transcription factors in Antirrhinum

Evolution of flower shape in Plantago lanceolata

Flower symmetry and shape in Antirrhinum

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