Generic Delimitation and Phylogeny of the Subtribe Centaureinae (Asteraceae): A Combined Nuclear and Chloroplast DNA Analysis

Centaurea Revisited: A Molecular Survey of the Jacea Group

Taxonomic complexity has hindered partitioning the genusCentaurea into natural subdivisions, even though it has long been recognized as an unwieldy, artificial assemblage. Most of the remaining difficulties center in theCentaurea jacea group, whose taxa share a common advanced type of pollen. Because it comprises half the species of the genusCentaurea, as well as five other disputed genera previously segregated fromCentaurea (Chartolepis, Cheirolepis, Cnicus, Grossheimia andTomanthea), theCentaurea jacea group is a significant taxonomic challenge. Newer molecular approaches are useful for resolving complex relationships because they provide more precise inferences of evolutionary relationships than traditional morphological characters. Sequences of the Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA were analyzed for a comprehensive sample of this group. Results indicated that theCentaurea jacea group is monophyletic and includes the segregated genera, but not two other genera (Oligochaeta andZoegea), whose inclusion in theCentaurea jacea group was doubtful. In addition to pollen morphology, the ITS phylogeny is also supported by karyological evidence and by good correlation with biogeographic distribution of the species. The monophyly of theCentaurea jacea group suggests that a natural delimitation ofCentaurea that minimizes nomenclatural changes is possible, but only if a new type of the genus is designated.

The natural delimitation ofCentaurea (Asteraceae: Cardueae): ITS sequence analysis of theCentaurea jacea group

Wagenitz, G. & Hellwig, F. H.: The genus Psephellus Cass. (Compositae, Cardueae) revisited with a broadened concept. - Willdenowia 30: 29-44. 2000. - ISSN 0511-9618. A new concept of the genus Psephellus is presented on the basis of morphological, anatomical, palynological and caryological evidence. The few molecular data seem to confirm the monophyly of the genus. The following former sections of Centaurea are included: C. sect. Psephelloideae, Psephellus, Hyalinella, Aetheopappus, Amblyopogon, Heterolophus, Czerniakovskya, Odontolophoideae, Odontolophus, Xanthopsis, Uralepis and Sosnovskya. New combinations under Psephellus are provided for these sections and for 35 species, especially from Turkey and Iran. Psephellus in this broadened sense has 75-80 species and a distribution with a centre in E Anatolia, Caucasia and NW Iran; only few species occur outside this area. Close relationships exist between different sections despite considerable differences especially in the characters of the pappus.

The genus Psephellus Cass. (Compositae, Cardueae) revisited with a

Wagenitz, G. & Hellwig, F. H.: The genus Psephellus Cass. (Compositae, Cardueae) revisited with a broadened concept. – Willdenowia 30: 29-44. 2000. – ISSN 0511-9618. A new concept of the genus Psephellus is presented on the basis of morphological, anatomical, palynological and caryological evidence. The few molecular data seem to confirm the monophyly of the genus. The following former sections of Centaurea are included: C. sect. Psephelloideae, Psephellus, Hyalinella, Aetheopappus, Amblyopogon, Heterolophus, Czerniakovskya, Odontolophoideae, Odontolophus, Xanthopsis, Uralepis and Sosnovskya. New combinations under Psephellus are provided for these sections and for 35 species, especially from Turkey and Iran. Psephellus in this broadened sense has 75-80 species and a distribution with a centre in E Anatolia, Caucasia and NW Iran; only few species occur outside this area. Close relationships exist between different sections despite considerable differences especially in the characters of the pappus.

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The genus Psephellus Cass. (Compositae, Cardueae) revisited with a broadened concept

New chromosome counts in the subtribe Centaureinae (Asteraceae, Cardueae) from West Asia☆

Megagametogenesis of soybean, Glycine max (L.) Merr., cultivars Clark and Clark k2, and F1 hybrid of Clark (female parent) crossed with Clark k2 (male parent) were studied using stereo light microscopy and confocal scanning laser microscopy. Reproductive development in Clark and Clark k2 plants was compared to F1 hybrid plants. In mature pods, 6.4% of the ovules of Clark, 8.1% of the ovules of Clark k2, and 41.4% of the ovules of F1 hybrid plants were aborted. This female partial sterility was due to incomplete megagametophyte development: undeveloped polar nuclei—or developed but not in a position for fertilization; increased megagametophyte wall thickness; abnormal shape and/or premature degeneration of synergids and intact synergids throughout the life of the ovule; egg cell not well-developed or absent; and megagametophyte remaining uninucleate. Each of these abnormalities contributed to either lack of double fertilization or early megagametophyte abortion.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1077&context=bot_pubs

Hilal Ilarslan

Papers

New chromosome counts in the subtribe Centaureinae (Asteraceae, Cardueae) from West Asia☆

Megagametophyte abnormalities of near-isogenic female partial-sterile soybean mutants ( Glycine max; Leguminosae).