1 research outputs found
Chromosome Numbers in the Genera Cousinia, Olgaea and Syreitschikovia (Compositae)
14 p. Il.[EN] The scarce karyological data available for both the Arctium-Cousinia
complex and the Onopordum group has led us to provide more data essential to
understand the karyological evolution of these taxa. Chromosome counts were made
on somatic metaphases using the squash technique. We report 20 chromosome
number records for the genus Cousinia s. lat. from the area of Near East and Central
Asia. Thirteen of them are first chromosome counts for the studied species, and the
remaining seven records provide confirmation of scarce or uncertain previous data.
We also present the first chromosome counts for three of the 13 sections of this
genus. Our records for Arctioid species show karyological uniformity with 2n=36.
In the Cousinioid group, 13 records agree with the three major numbers of its
characteristic dysploidy series 2n=22, 24 and 26. We report first chromosome counts
for the genera Olgaea and Syreitschikovia from Kazakhstan, being 2n=26 and 24,
respectively. Our results confirm a hypothesis that the Arctioid and Cousinioid
clades, although forming a monophyletic group, have followed different evolutionary
paths. In the Onopordum group, our results confirm the existence of two lineages; the
colonizing biennial taxa are characterized by n=17, while the perennial genera
have n=12, 13. The evidence for recent polyploidization is absent in both the
Arctium-Cousinia complex and the Onopordum group.Peer reviewe