Chromosome numbers and karyotype evolution in holoparasitic Orobanche (Orobanchaceae) and related genera

Abstract

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.

A plastid gene phylogeny of the non-photosynthetic parasitic Orobanche (Orobanchaceae) and related genera

“…(Schneeweiss et al 2004a), for which no amplification could be achieved in several trials, does not allow any final conclusions to be drawn. In agreement with previous studies Young et al 1999;Schneeweiss et al 2004a;Wolfe et al 2005;Young and dePamphilis 2005;Bennett and Mathews 2006), the two American groups (each monophyletic with BS/PP 98-100/100) are reciprocally monophyletic sister-taxa (BS/PP 99/1.00), which is supported by the shared chromosome base number of x = (12) 24 (Schneeweiss et al 2004b). This conclusion is robust despite the low number of accessions included in the present study, because identical results are obtained from analysis of a comprehensive data set of nuclear ITS and ETS sequences from Aphyllon and Myzorrhiza (syn.…”

“…2). Despite being inconclusive concerning the monophyly of Orobanche s. l., the rps2 data agree with the recognition of five major lineages suggested by pronounced morphological, karyological and cytological differences (Beck-Mannagetta 1930;Teryokhin et al 1993;Schneeweiss et al 2004b;WeissSchneeweiss et al 2006), which should best be translated into a narrower generic concept as already suggested by Holub (1977Holub ( , 1990, Teryokhin et al (1993) and Carlón et al (2005).…”

Genetic variability of Orobanche aegyptiaca infesting tobacco in Iran by Bayesian analysis

“…The genus Orobanche, commonly known as broomrape, is the largest among the holoparasitic members of Orobanchaceae, and contains over 200 achlorophyllous species which parasitize the roots of various host plants (Parker & Riches 1993;Schneeweiss et al 2004). This genus is divided into four sections: Gymnocaulis Nutt., Myzorrhiza (Phil.)…”

“…Individual species of the genus Orobanche are difficult to distinguish morphologically, which has led to interest in molecular taxonomic differentiation (Román et al 2001;Benharrat et al 2002;Buschmann et al 2005). Schneeweiss et al (2004) in view of karyological variability recorded three basic sets of chromosomes, x = 19, x = 12 and x = 24, in the genus Orobanche. The first basic set has been found in the members of the section Orobanche, the second in the sections Myzorrhiza and Trionychon, and the third in the section Gymnocaulis.…”

The alien flora of terrestrial and marine ecosystems of Rodos island (Se Aegean), Greece

“…S. Rätzel, P. Hein & E. von Raab-Straube In the last few years, plant scientists, in following Schneeweiss & al. (2004aSchneeweiss & al. ( , 2004b (Schneeweiss & al.…”