Astragalus section Hymenostegis is one of the important characteristic elements of thorn-cushion ... more Astragalus section Hymenostegis is one of the important characteristic elements of thorn-cushion formations in the Irano-Turanian floristic region. In this paper, we examined the chromosome number of 17 species (15 new reports) and provide estimates of genome size for 62 individuals belonging to 38 taxa of A. sect. Hymenostegis, some species outside this section, plus two Oxytropis species. Based on chromosome counts 11 species were found to be diploid (2n = 16), four species tetraploid (2n = 32) and two taxa hexaploid (2n = 48). From genome size measurements on silica-gel dried material, three ploidy levels (2x, 4x and 6x) were inferred, with a majority of species being diploid. The 2C values reach from 2.07 pg in diploid Astragalus zohrabi to 7.16 pg in hexaploid A. rubrostriatus. We found indications that species might occur with different cytotypes. A phylogenetic framework using nrDNA ITS sequences was constructed to understand the evolution of ploidy changes and genome sizes. ...
Astragalus section Hymenostegis is one of the important characteristic elements of thorn-cushion ... more Astragalus section Hymenostegis is one of the important characteristic elements of thorn-cushion formations in the Irano-Turanian floristic region. In this paper, we examined the chromosome number of 17 species (15 new reports) and provide estimates of genome size for 62 individuals belonging to 38 taxa of A. sect. Hymenostegis, some species outside this section, plus two Oxytropis species. Based on chromosome counts 11 species were found to be diploid (2n = 16), four species tetraploid (2n = 32) and two taxa hexaploid (2n = 48). From genome size measurements on silica-gel dried material, three ploidy levels (2x, 4x and 6x) were inferred, with a majority of species being diploid. The 2C values reach from 2.07 pg in diploid Astragalus zohrabi to 7.16 pg in hexaploid A. rubrostriatus. We found indications that species might occur with different cytotypes. A phylogenetic framework using nrDNA ITS sequences was constructed to understand the evolution of ploidy changes and genome sizes. ...
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Papers by zahra nemati