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Chromosome numbers and karyotype evolution in holoparasitic Orobanche (Orobanchaceae) and related genera
Author(s) -
Schneeweiss Gerald M.,
Palomeque Teresa,
Colwell Alison E.,
WeissSchneeweiss Hanna
Publication year - 2004
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.91.3.439
Subject(s) - orobanche , orobanchaceae , biology , botany , phylogenetic tree , zoology , genetics , gene , germination
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.