Journal
AMERICAN JOURNAL OF BOTANY
Volume 91, Issue 3, Pages 439-448Publisher
WILEY
DOI: 10.3732/ajb.91.3.439
Keywords
chromosome number evolution; Cistanche; Diphelypaea; karyotype evolution; Orobanche; Phelipanche
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Chromosome numbers and karyotypes of species of Orobanche, Cistanche, and Diphelypaea (Orobanchaceae) were investigated, and 108 chromosome counts of 53 taxa, 19 counted for the first time, are presented with a thorough compilation of previously published data. Additionally, karyotypes of representatives of these genera, including Orobanche sects. Orobanche and Trionychon, are reported. Cistanche (x=20) has large meta- to submetacentric chromosomes, while those of Diphelypaea (x=19) are medium-sized submeta- to acrocentrics. Within three analyzed sections of Orobanche, sects. Myzorrhiza (x=24) and Trionychon (x=12) possess medium-sized submeta- to acrocentrics, while sect. Orobanche (x=19) has small, mostly meta- to submetacentric, chromosomes. Polyploidy is unevenly distributed in Orobanche and restricted to a few lineages, e.g., O. sect. Myzorrhiza or Orobanche gracilis and its relatives (sect. Orobanche). The distribution of basic chromosome numbers supports the groups found by molecular phylogenetic analyses: Cistanche has x=20, the Orobanche-group (Orobanche sect. Orobanche, Diphelypaea) has x=19, and the Phelipanche-group (Orobanche sects. Gymnocaulis, Myzorrhiza, Trionychon) has x=12, 24. A model of chromosome number evolution in Orobanche and related genera is presented: from two ancestral base numbers, x(h)=5 and x(h)=6, independent polyploidizations led to x=20 (Cistanche) and (after dysploidization) x=19 (Orobanche-group) and to x=12 and x=24 (Phelipanche-group), respectively.
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