Molecular phylogeny and evolution of floral characters of Artemisia and allies (Anthemideae, Asteraceae): Evidence from nrDNA ETS and ITS sequences

Taxon (Impact Factor: 3.3). 01/2008; 57(1):66-78. DOI: 10.2307/25065949


To better understand the evolutionary history of the genus Artemisia (Anthemideae, Asteraceae) and its relationships to other genera of the subtribes Artemisiinae, Leucantheminae and Tanacetinae, 63 sequences of the external and 10 of the internal transcribed spacer of nuclear ribosomal DNA (ETS and ITS) were newly generated. Analyses were performed on the combined dataset using maximum parsimony, maximum likelihood and Bayesian inference. The combined analysis supports that all Artemisiinae genera included plus Hippolytia (subtribe Tanacetinae) and Nipponanthemum (subtribe Leucantheminae) constitute a monophyletic group. Within this group, a successive branching shows three monophyletic groups: (1) Nipponanthemum/Hippolytia/Brachanthemum; (2) the Dendranthema group; and (3) the Artemisia/Kaschgaria group. Within the latter, a new sister-group relationship is found between the monophyletic genus Kaschgaria and the Artemisia group, which comprises two main evolutionary lineages: (i) the Dracunculus clade including various Artemisia species and four Asian genera: Filifolium, Mausolea, Neopallasia and Turaniphytum; and (ii) the remaining subgenera of Artemisia plus the two North American genera: Picrothamnus and Sphaeromeria. Within this phylogenetic framework the evolution of two important characters (capitula and pollen type) in the group was inferred. Character reconstruction reveals that discoid capitula and Anthemis pollen type are the ancestral condition in the subtribe. The Artemisia/Kaschgaria lineage probably originated from an ancestor with disciform capitula, central hermaphrodite florets and Artemisia pollen type. Molecular evidence of several biogeographical migration routes of the genus Artemisia is presented.

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    • "Artemisia species are mostly perennial and particularly diverse in mountains, grasslands and semidesertic areas (Ling et al. 2006). The traditional classification of the genus, which relies on capitulum characters, is partially incongruent to lineages identified in molecular studies (Sanz et al. 2008). Nevertheless, the classical subgenera [Artemisia, Absinthium (Mill.) "
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    ABSTRACT: Molecular cytogenetics and the study of genome size have been used to understand evolutionary and systematic relationships in many species. However, this approach has seldom been applied to alpine plants. A group of dysploid–polyploid high mountain Artemisia species, distributed from the European Sierra Nevada to Central Asian mountains, through the Pyrenees, the Alps and the Caucasus, is a good model to consider changes at the genome and chromosome levels. These small perennial Artemisia, found frequently in isolated populations, present highly disjunct distributions. Some are considered rare or even endangered. Here, we show results for nine species and 31 populations, including genome size (2C-values), fluorochrome banding and fluorescent in situ hybridisation of ribosomal RNA genes (rDNA). Significant intraspecific genome size variation is found in certain populations of A. eriantha and A. umbelliformis, but without taxonomic significance due to the absence of morphological or ecological differentiation. The number and position of GC-rich DNA bands is mostly coincidental with rDNA although there is an expansion of GC-rich heterochromatin in centromeres in some taxa. Ancestral character states have been reconstructed and x = 9 is inferred as the likely ancestral base number, while the dysploid x = 8 has appeared repeatedly during the evolution of Artemisia. On the basis of cytological observations, Robertsonian translocations are proposed for the appearance of dysploidy in the genus. A remarkable presence of x = 8-based species has been detected in the clade including high mountain species, which highlights the important role of dysploidy in the diversification of high mountain Artemisia. Conversely, polyploidy, though present in the alpine species, is more common in the rest of the genus, particularly in arctic species. Hypotheses on the mechanisms underpinning the relative abundance of dysploids and scarcity of polyploids in high mountain Artemisia are discussed.
    Full-text · Article · Nov 2015 · Alpine Botany
    • "The nuclear nrDNA ITS and ETS regions were amplified by PCR and sequenced using the same conditions as described in Sanz et al. (2008).Nucleotide sequences were assembled and edited using BioEdit v. 7.0.9 (Hall, 1999). "
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    ABSTRACT: Cheirolophus uliginosus is a rare species, endemic to the south-western Iberian Peninsula, and listed as a characteristic taxon from the temperate Atlantic wet heaths, a priority habitat for conservation by the European Union. The conservation status of this species in most of its distribution area is poorly known, but, in recent times, some populations have disappeared and there has been a reduction in the number of individuals in others. In this context, we analysed the effects of population size on genetic diversity, revealing that genetic erosion and inbreeding depression could be having a significant impact on smaller populations. Furthermore, we studied the patterns of genetic structure and variability at the species level, finding a strikingly low within-population diversity and high among-population genetic differentiation. Finally, the genetic structure analyses suggested a long and complex phylogeographical history of C. uliginosus in the region, in agreement with the climate relict status proposed for this species. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, ●●, ●●–●●.
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    • "Chrysanthemum L. has radiate flower heads, whereas Artemisia, Elachanthemum, and Stilpnolepis have discoid capitula, and Ajania is characterized by disciform capitula. Although Chrysanthemum and Ajania are clear-cut in terms of capitulum architecture, they belong to a monophyletic group where their species are completely intermingled (Watson et al., 2002; Sanz et al., 2008; Masuda et al., 2009; Zhao et al., 2010; Liu et al., 2012). Obviously, the two genera share a most recent common ancestor and should be similar in genomic components including genes regulating capitulum morphoogy . "
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    ABSTRACT: Asteraceae are distinguishable by their head-like inflorescence called capitulum. There are a variety of capitulum types due to different combinations of different composing florets. Morphological evolution of capitula must involve homoplasy under selective constrains. Therefore, a comparative examination of ontogenies of divergent capitula among phylogenetically close taxa is important to investigate the genetic and molecular bases of this trait. In the subtribe Artemisiinae, tribe Anthemideae, three closely related genera have different flower heads: Chrysanthemum with the radiate, Ajania with the disciform and Stilpnolepis with the discoid capitula. Through observations using scanning electron microscopy (SEM), we examined morphogenetic processes of flower heads of representative species of these genera. The morphological differentiation of the discoid from the radiate/disciform capitula happened early since the floral initiation stage. The development of the ray/marginal florets of the radiate/disciform capitula lagged behind throughout the phases of floral initiation and floral organogenesis. Primordia of their 1–2 dorsal corolla lobes and all stamens ceased to grow soon after initiation. In contrast, all florets on a discoid capitulum developed equally in rates and modes into bisexual actinomorphic flowers. Differentiation between the radiate and the disciform capitula occurred late during the floral maturation stage. Our data provided evidence to the interpretation that uniformly acropetal development only occurs in species with homogamous flower heads, and to the idea that the timing of ontogenetic divergence between taxa is positively correlated with the phylogenetic distance of the taxa.
    No preview · Article · Apr 2015 · Journal of Systematics and Evolution
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