PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-5 (5)
 

Clipboard (0)
None

Select a Filter Below

Journals
Authors
more »
Year of Publication
Document Types
1.  Specific Duplication and Dorsoventrally Asymmetric Expression Patterns of Cycloidea-Like Genes in Zygomorphic Species of Ranunculaceae 
PLoS ONE  2014;9(4):e95727.
Floral bilateral symmetry (zygomorphy) has evolved several times independently in angiosperms from radially symmetrical (actinomorphic) ancestral states. Homologs of the Antirrhinum majus Cycloidea gene (Cyc) have been shown to control floral symmetry in diverse groups in core eudicots. In the basal eudicot family Ranunculaceae, there is a single evolutionary transition from actinomorphy to zygomorphy in the stem lineage of the tribe Delphinieae. We characterized Cyc homologs in 18 genera of Ranunculaceae, including the four genera of Delphinieae, in a sampling that represents the floral morphological diversity of this tribe, and reconstructed the evolutionary history of this gene family in Ranunculaceae. Within each of the two RanaCyL (Ranunculaceae Cycloidea-like) lineages previously identified, an additional duplication possibly predating the emergence of the Delphinieae was found, resulting in up to four gene copies in zygomorphic species. Expression analyses indicate that the RanaCyL paralogs are expressed early in floral buds and that the duration of their expression varies between species and paralog class. At most one RanaCyL paralog was expressed during the late stages of floral development in the actinomorphic species studied whereas all paralogs from the zygomorphic species were expressed, composing a species-specific identity code for perianth organs. The contrasted asymmetric patterns of expression observed in the two zygomorphic species is discussed in relation to their distinct perianth architecture.
doi:10.1371/journal.pone.0095727
PMCID: PMC3994137  PMID: 24752428
2.  Resurrection of the genus Staphisagria J. Hill, sister to all the other Delphinieae (Ranunculaceae)  
PhytoKeys  2011;21-26.
Molecular sequence data show that the three species oDelphinium subg. Staphisagria (J. Hill) Peterm. form the sister clade to Aconitum L., Aconitella SpachConsolida (DC.) S.F. Gray, and all remaining species of Delphinium L. To account for this finding we resurrect Staphisagria J. Hill (1756). Names in Staphisagria are available for two of the species. We here make the required new combination for the third species, Staphisagria picta (Willd.) F. Jabbour, provide a key to the species, and illustrate one of them.
doi:10.3897/phytokeys.7.2010
PMCID: PMC3261041  PMID: 22287922
Aconitum; Delphinium; Mediterranean region; molecular phylogeny; nomenclature; Staphisagria
3.  Establishment of zygomorphy on an ontogenic spiral and evolution of perianth in the tribe Delphinieae (Ranunculaceae) 
Annals of Botany  2009;104(5):809-822.
Background and Aims
Ranunculaceae presents both ancestral and derived floral traits for eudicots, and as such is of potential interest to understand key steps involved in the evolution of zygomorphy in eudicots. Zygomorphy evolved once in Ranunculaceae, in the speciose and derived tribe Delphinieae. This tribe consists of two genera (Aconitum and Delphinium s.l.) comprising more than one-quarter of the species of the family. In this paper, the establishment of zygomorphy during development was investigated to cast light on the origin and evolution of this morphological novelty.
Methods
The floral developmental sequence of six species of Ranunculaceae, three actinomorphic (Nigella damascena, Aquilegia alpina and Clematis recta) and three zygomorphic (Aconitum napellus, Delphinium staphisagria and D. grandiflorum), was compared. A developmental model was elaborated to break down the successive acquisitions of floral organ identities on the ontogenic spiral (all the species studied except Aquilegia have a spiral phyllotaxis), giving clues to understanding this complex morphogenesis from an evo-devo point of view. In addition, the evolution of symmetry in Ranunculaceae was examined in conjunction with other traits of flowers and with ecological factors.
Key Results
In the species studied, zygomorphy is established after organogenesis is completed, and is late, compared with other zygomorphic eudicot species. Zygomorphy occurs in flowers characterized by a fixed merism and a partially reduced and transformed corolla.
Conclusions
It is suggested that shifts in expression of genes controlling the merism, as well as floral symmetry and organ identity, have played a critical role in the evolution of zygomorphy in Delphinieae, while the presence of pollinators able to exploit the peculiar morphology of the flower has been a key factor for the maintenance and diversification of this trait.
doi:10.1093/aob/mcp162
PMCID: PMC2749547  PMID: 19608573
Delphinieae; development; evolution; evo-devo; nectar spurs; ontogenic spiral; Ranunculaceae; zygomorphy
4.  Evolutionary Trends in the Flowers of Asteridae: Is Polyandry an Alternative to Zygomorphy? 
Annals of Botany  2008;102(2):153-165.
Background and Aims
Floral symmetry presents two main states in angiosperms, actinomorphy (polysymmetry or radial symmetry) and zygomorphy (monosymmetry or bilateral symmetry). Transitions from actinomorphy to zygomorphy have occurred repeatedly among flowering plants, possibly in coadaptation with specialized pollinators. In this paper, the rules controlling the evolution of floral symmetry were investigated to determine in which architectural context zygomorphy can evolve.
Methods
Floral traits potentially associated with perianth symmetry shifts in Asteridae, one of the major clades of the core eudicots, were selected: namely the perianth merism, the presence and number of spurs, and the androecium organ number. The evolution of these characters was optimized on a composite tree. Correlations between symmetry and the other morphological traits were then examined using a phylogenetic comparative method.
Key Results
The analyses reveal that the evolution of floral symmetry in Asteridae is conditioned by both androecium organ number and perianth merism and that zygomorphy is a prerequisite to the emergence of spurs.
Conclusions
The statistically significant correlation between perianth zygomorphy and oligandry suggests that the evolution of floral symmetry could be canalized by developmental or spatial constraint. Interestingly, the evolution of polyandry in an actinomorphic context appears as an alternative evolutionary pathway to zygomorphy in Asteridae. These results may be interpreted either in terms of plant–pollinator adaptation or in terms of developmental or physical constraints. The results are discussed in relation to current knowledge about the molecular bases underlying floral symmetry.
doi:10.1093/aob/mcn082
PMCID: PMC2712368  PMID: 18511411
Floral symmetry; architectural constraints; Asteridae; comparative analysis; composite tree; correlated evolution; evolutionary scenario
5.  Cophylogeny of the anther smut fungi and their caryophyllaceous hosts: Prevalence of host shifts and importance of delimiting parasite species for inferring cospeciation 
Background
Using phylogenetic approaches, the expectation that parallel cladogenesis should occur between parasites and hosts has been validated in some studies, but most others provided evidence for frequent host shifts. Here we examine the evolutionary history of the association between Microbotryum fungi that cause anther smut disease and their Caryophyllaceous hosts. We investigated the congruence between host and parasite phylogenies, inferred cospeciation events and host shifts, and assessed whether geography or plant ecology could have facilitated the putative host shifts identified.
For cophylogeny analyses on microorganisms, parasite strains isolated from different host species are generally considered to represent independent evolutionary lineages, often without checking whether some strains actually belong to the same generalist species. Such an approach may mistake intraspecific nodes for speciation events and thus bias the results of cophylogeny analyses if generalist species are found on closely related hosts. A second aim of this study was therefore to evaluate the impact of species delimitation on the inferences of cospeciation.
Results
We inferred a multiple gene phylogeny of anther smut strains from 21 host plants from several geographic origins, complementing a previous study on the delimitation of fungal species and their host specificities. We also inferred a multi-gene phylogeny of their host plants, and the two phylogenies were compared. A significant level of cospeciation was found when each host species was considered to harbour a specific parasite strain, i.e. when generalist parasite species were not recognized as such. This approach overestimated the frequency of cocladogenesis because individual parasite species capable of infecting multiple host species (i.e. generalists) were found on closely related hosts. When generalist parasite species were appropriately delimited and only a single representative of each species was retained, cospeciation events were not more frequent than expected under a random distribution, and many host shifts were inferred.
Current geographic distributions of host species seemed to be of little relevance for understanding the putative historical host shifts, because most fungal species had overlapping geographic ranges. We did detect some ecological similarities, including shared pollinators and habitat types, between host species that were diseased by closely related anther smut species. Overall, genetic similarity underlying the host-parasite interactions appeared to have the most important influence on specialization and host-shifts: generalist multi-host parasite species were found on closely related plant species, and related species in the Microbotryum phylogeny were associated with members of the same host clade.
Conclusion
We showed here that Microbotryum species have evolved through frequent host shifts to moderately distant hosts, and we show further that accurate delimitation of parasite species is essential for interpreting cophylogeny studies.
doi:10.1186/1471-2148-8-100
PMCID: PMC2324105  PMID: 18371215

Results 1-5 (5)