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Nielsen, Karen Margrethe; Deroles, Simon C.; Markham, Kenneth R.; Bradley, Marie; Podivinsky, Ellen; Manson, David G.

doi:10.1023/a:1020320809654

Cited by 75 publications

(28 citation statements)

References 28 publications

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“…Mitchell petunia is a commonly used line for plant transformation studies, and the changes in phenotype observed here have not been observed when using a wide range of other transformation vectors (e.g., Deroles and Gardner, 1988; Davies et al, 2003; Lewis et al, 2006). The same applies for lisianthus, as phenotypes similar to those found here have not been observed when transgenics of the same cultivars have been generated with either empty vector controls or transformation vectors for various flavonoid biosynthetic genes (Ledger et al, 1997; Schwinn et al, 1997; Deroles et al, 1998; Nielsen et al, 2002). …”

Section: Discussionsupporting

confidence: 65%

“…Based on the color of the precociously pigmented flowers of ROS1-lisianthus, cyanidin-derived anthocyanins accumulated at this stage, not the delphinidin-derived anthocyanins found in the mature petals. This indicates that the genes encoding the flavonoid 3′5′ hydroxylase (F3′5′H) were not up-regulated by the 35S:ROS1 transgene, and matches the pigment types seen in line 54 transgenics containing an antisense flavonol synthase transgene that redirects flavonoid biosynthesis from flavonols to anthocyanins (Nielsen et al, 2002). Variability in the activation of F3′5′H genes by R2R3-MYB/bHLH transgenes has been found previously, with ROS1/DELILA but not LC/C1 activating the F3′5′H of tomato (Butelli et al, 2008).…”

Section: Discussionsupporting

confidence: 52%

“…The origin of the purple-flowered lisianthus cv. 54 is described in Davies et al (1993), and further characterized in Nielsen et al (2002). Flower development in lisianthus cv.…”

Section: Methodsmentioning

confidence: 99%

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MYB and bHLH transcription factor transgenes increase anthocyanin pigmentation in petunia and lisianthus plants, and the petunia phenotypes are strongly enhanced under field conditions

et al. 2014

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Petunia line Mitchell [MP, Petunia axillaris × (P. axillaris × P. hybrida)] and Eustoma grandiflorum (lisianthus) plants were produced containing a transgene for over-expression of the R2R3-MYB transcription factor [TF; ROSEA1 (ROS1)] that up-regulates flavonoid biosynthesis in Antirrhinum majus. The petunia lines were also crossed with previously produced MP lines containing a Zea mays flavonoid-related basic helix-loop-helix TF transgene (LEAF COLOR, LC), which induces strong vegetative pigmentation when these 35S:LC plants are exposed to high-light levels. 35S:ROS1 lisianthus transgenics had limited changes in anthocyanin pigmentation, specifically, precocious pigmentation of flower petals and increased pigmentation of sepals. RNA transcript levels for two anthocyanin biosynthetic genes, chalcone synthase and anthocyanidin synthase, were increased in the 35S:ROS1 lisianthus petals compared to those of control lines. With MP, the 35S:ROS1 calli showed novel red pigmentation in culture, but this was generally not seen in tissue culture plantlets regenerated from the calli or young plants transferred to soil in the greenhouse. Anthocyanin pigmentation was enhanced in the stems of mature 35S:ROS1 MP plants, but the MP white-flower phenotype was not complemented. Progeny from a 35S:ROS1 × 35S:LC cross had novel pigmentation phenotypes that were not present in either parental line or MP. In particular, there was increased pigment in the petal throat region, and the anthers changed from yellow to purple pigmentation. An outdoor field trial was conducted with the 35S:ROS1, 35S:LC, 35S:ROS1 × 35S:LC and control MP lines. Field conditions rapidly induced intense foliage pigmentation in 35S:LC plants, a phenotype not observed in control MP or equivalent 35S:LC plants maintained in a greenhouse. No difference in plant stature, seed germination, or plant survival was observed between transgenic and control plants.

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Section: Discussionsupporting

confidence: 65%

Section: Discussionsupporting

confidence: 52%

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MYB and bHLH transcription factor transgenes increase anthocyanin pigmentation in petunia and lisianthus plants, and the petunia phenotypes are strongly enhanced under field conditions

et al. 2014

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“…However, it is worth noting that many searches for color loci have focused on candidate genes required for anthocyanin biosynthesis, so FLS has not received much attention. Additionally, FLS has been targeted to induce a switch between two anthocyanin pigments in genetically-engineered systems (Table S1) (Nakatsuka et al 2007;Nielsen et al 2002). Based on our simulated results, FLS can therefore be thought of as a hotspot for missing mutations that we may expect to observe often in nature, but so far have only observed very rarely.…”

Section: Discussionmentioning

confidence: 87%

“…This experimental design is in line with empirical work, where species can shift between pigment types while keeping the total anthocyanin levels relatively constant (Berardi et al 2016;Esfeld et al 2018), resulting in owers of dierent hues but similar color intensity. Natural and engineered systems also evidence trade-os between anthocyanins and avonols, suggesting constraints on total avonoid content (Davies et al 2003;Nakatsuka et al 2007;Nielsen et al 2002;Yuan et al 2016). For mutations falling within the tolerance, a selection coecient is calculated using the tness function:…”

Section: Design Scheme For the Evolutionary Simulationsmentioning

confidence: 99%

Structure and contingency determine mutational hotspots for flower color evolution

Wheeler¹,

Wing²,

Smith³

2020

Preprint

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Evolutionary genetic studies have uncovered abundant evidence for genomic hotspots of phenotypic evolution, as well as biased patterns of mutations at those loci. However, the theoretical basis for this concentration of particular types of mutations at particular loci remains largely unexplored. In addition, historical contingency is known to play a major role in evolutionary trajectories, but has not been reconciled with the existence of such hotspots. For example, do the appearance of hotspots and the fixation of different types of mutations at those loci depend on the starting state and/or on the nature and direction of selection? Here we use a computational approach to examine these questions, focusing the anthocyanin pigmentation pathway, which has been extensively studied in the context of flower color transitions. We investigate two transitions that are common in nature, the transition from blue to purple pigmentation and from purple to red pigmentation. Both sets of simulated transitions occur with a small number of mutations at just four loci and show strikingly similar peaked shapes of evolutionary trajectories, with the mutations of largest effect occurring early but not first. Nevertheless, the types of mutations (biochemical vs. regulatory) as well as their direction and magnitude are contingent on the particular transition. These simulated color transitions largely mirror findings from natural flower color transitions, which are known to occur via repeated changes at a few hotspot loci. Still, some types of mutations observed in our simulated color evolution are rarely observed in nature, suggesting that pleiotropic effects further limit the trajectories between color phenotypes. Overall, our results indicate that the branching structure of the pathway leads to a predictable concentration of evolutionary change at hotspot loci, but the types of mutations at these loci and their order is contingent on the evolutionary context.

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Biochemistry and Genetics of Flower Color

Griesbach¹

2005

Plant Breeding Reviews

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Untitled

Cited by 75 publications

References 28 publications

MYB and bHLH transcription factor transgenes increase anthocyanin pigmentation in petunia and lisianthus plants, and the petunia phenotypes are strongly enhanced under field conditions

MYB and bHLH transcription factor transgenes increase anthocyanin pigmentation in petunia and lisianthus plants, and the petunia phenotypes are strongly enhanced under field conditions

Structure and contingency determine mutational hotspots for flower color evolution

Biochemistry and Genetics of Flower Color

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