Meristic changes in flowering plants: How flowers play with numbers

Craene, Louis Ronse De

doi:10.1016/j.flora.2015.08.005

Cited by 81 publications

(43 citation statements)

References 92 publications

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“…The number of organs of a specific type in a whorl – merism (Ronse De Craene & Smets, ; Ronse De Craene, ) (Fig. b) – is relatively fixed for each whorl, and usually occurs as two, three, four or five organs per whorl, with trimery and pentamery the most frequent patterns.…”

Section: What Is the Floral Ground Plan?mentioning

confidence: 99%

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Evolution and genetic control of the floral ground plan

Smyth

2018

New Phytologist

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Contents Summary70I.Introduction70II.What is the floral ground plan?71III.Diversity and evolution of the floral ground plan72IV.Genetic mechanisms77V.What's next?82Acknowledgements83References83 Summary The floral ground plan is a map of where and when floral organ primordia arise. New results combining the defined phylogeny of flowering plants with extensive character mapping have predicted that the angiosperm ancestor had whorls rather than spirals of floral organs in large numbers, and was bisexual. More confidently, the monocot ancestor likely had three organs in each whorl, whereas the rosid and asterid ancestor (Pentapetalae) had five, with the perianth now divided into sepals and petals. Genetic mechanisms underlying the establishment of the floral ground plan are being deduced using model species, the rosid Arabidopsis, the asterid Antirrhinum, and in grasses such as rice. In this review, evolutionary and genetic conclusions are drawn together, especially considering how known genes may control individual processes in the development and evolution of ground plans. These components include organ phyllotaxis, boundary formation, organ identity, merism (the number or organs per whorl), variation in the form of primordia, organ fusion, intercalary growth, floral symmetry, determinacy and, finally, cases where the distinction between flowers and inflorescences is blurred. It seems likely that new pathways of ground plan evolution, and new signalling mechanisms, will soon be uncovered by integrating morphological and genetic approaches.

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Section: What Is the Floral Ground Plan?mentioning

confidence: 99%

“…In general, how might the number of organs per whorl increase or decrease during evolution (Ronse De Craene & Smets, ; Ronse De Craene, , )? At least three general scenarios can be proposed.…”

Section: Genetic Mechanismsmentioning

confidence: 99%

Evolution and genetic control of the floral ground plan

Smyth

2018

New Phytologist

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“…Anemone flowers frequently have intraspecific variation in tepal numbers within populations, as seen in many angiosperm clades [7,8]. For example, variation in A. flaccida indicated that the basic (i.e., most stable) number of tepals is five, whereas .…”

Section: Introductionmentioning

confidence: 99%

Stochastic occurrence of trimery from pentamery in floral phyllotaxis of Anemone (Ranunculaceae)

Kitazawa

Fujimoto

2016

Acta Soc Bot Pol

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Merosity, indicating the basic number of floral organs such as sepals and petals, has been constrained to specific and stable numbers during the evolution of angiosperms. The ancestral flower is considered to have a spiral arrangement of perianth organs, as in phyllotaxis, the arrangement of leaves. How has the ancestral spiral evolved into flowers with specific merosities? To address this question, we studied perianth organ arrangement in the Anemone genus of the basal eudicot family Ranunculaceae, because various merosities are found in this genus. In three species, A. flaccida, A. scabiosa, and A. nikoensis that are normally pentamerous, we found positional arrangement of the excessive sixth perianth organ indicating the possibility of a transition from pentamerous to trimerous arrangement. Arrangement was intraspecifically stochastic, but constrained to three of five types, where trimerous arrangement was the most frequent in all species except for a form of A. scabiosa. The rank of frequency of the other two types was species-dependent. We connect these observations with classical theories of spiral phyllotaxis. The phyllotaxis model for initiation of the sixth organ showed that the three arrangements occur at a divergence angle <144°, indicating the spiral nature of floral phyllotaxis rather than a perfect penta-radial symmetry of 144°. The model further showed that selective occurrence of trimerous arrangement is mainly regulated by the organ growth rate. Differential organ growth as well as divergence angle may regulate transitions between pentamerous and trimerous flowers in intraspecific variation as well as in species evolution.

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“…The Anthonotha clade also displays high levels of intraspecific variation in petal and stamen number with four and three independent transitions, respectively (Table S2). A high level of intraspecific variation has been observed in early diverging angiosperms, including lineages of eudicots sister to core asterid and rosid clades (Ronse De Craene, 2015). However, intraspecific variation is not a common feature of the more derived core eudicot clades.…”

Section: Discussionmentioning

confidence: 99%

Phylogenomics within the Anthonotha clade (Detarioideae, Leguminosae) reveals a high diversity in floral trait shifts and a general trend towards organ number reduction

Ojeda¹,

Koenen²,

Cervantes³

et al. 2019

Preprint

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0Detarioideae is well known for its high diversity of floral traits, including flower symmetry, number 3 1 of organs, and petal size and morphology. This diversity has been characterized and studied at higher 3 2 taxonomic levels, but limited analyses have been performed among closely related genera with 3 3 contrasting floral traits due to the lack of fully resolved phylogenetic relationships. Here, we used 3 4 four representative transcriptomes to develop an exome capture bait for the entire subfamily and 3 5 applied it to the Anthonotha clade using a complete data set (61 specimens) representing all extant 3 6 floral diversity. Our phylogenetic analyses recovered congruent topologies using ML and Bayesian 3 7 methods. The genus Anthonotha was recovered as monophyletic contrary to the remaining three 3 8 genera (Englerodendron, Isomacrolobium and Pseudomacrolobium), which form a monophyletic 3 9 group sister to Anthonotha. We inferred a total of 35 transitions for the seven floral traits (pertaining 4 0to flower symmetry, petals, stamens and staminodes) that we analyzed, suggesting that at least 30% 4 1 of the species in this group display transitions from the ancestral condition reconstructed for the 4 2 Anthonotha clade. The main transitions were towards a reduction in the number of organs (petals, 4 3 stamens and staminodes). Despite the high number of transitions, our analyses indicate that the seven 4 4 characters are evolving independently in these lineages. Petal morphology is the most labile floral 4 5 trait with a total of seven independent transitions in number and seven independent transitions to 4 6 modification in petal types. The diverse petal morphology along the dorsoventral axis of symmetry 4 7 within the flower is not associated with differences at the micromorphology of petal surface, 4 8suggesting that in this group all petals within the flower might possess the same petal identity at the 4 9 molecular level. Our results provide a solid evolutionary framework for further detailed analyses of 5 0

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Meristic changes in flowering plants: How flowers play with numbers

Cited by 81 publications

References 92 publications

Evolution and genetic control of the floral ground plan

Evolution and genetic control of the floral ground plan

Stochastic occurrence of trimery from pentamery in floral phyllotaxis of Anemone (Ranunculaceae)

Phylogenomics within the Anthonotha clade (Detarioideae, Leguminosae) reveals a high diversity in floral trait shifts and a general trend towards organ number reduction

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