Karyomorphology of Maianthemum sensu lato (Polygonatae, Ruscaceae)

Abstract

We report results of karyotype analyses using nine species of Maianthemum from China. The species, except M. atropurpureum (with 2n=72), had 2n=36, and the results support the earlier suggestion that Maianthemum has x=18 with 2n=36 in most species. The species examined, however, showed marked differences in karyotype, particularly in the numbers of metacentric, submetacentric, and acrocentric chromosomes as well as in the number of satellites. In addition, we distinguished three different modes based on the number of clear gaps in chromosome length variation: unimodal, bimodal, and trimodal. The unimodal variation (with no gap) was found in M. dahuricum and M. atropurpureum, the bimodal variation (with one gap) in M. tatsienense, and the trimodal variation (with two gaps) in M. bifolium, M. forrestii, M. japonicum, M. henryi, M. purpureum, and M. lichiangense. In the trimodal variation, the positions of the two gaps may differ from species to species. In addition, the frequency of acrocentric chromosomes per complement was generally higher in the trimodal variation than in the unimodal and bimodal variations. Results of our analyses, which had not been clearly presented prior to this, may provide a better understanding of species evolution in the tribe Polygonatae.

Phylogeny and biogeographic diversification of Maianthemum (Ruscaceae: Polygonatae)

“…The characters of terminal paniculate to racemose inflorescences and spotted immature berries are synapomorphic for Maianthemum (LaFrankie, 1986a, b;Judd, 2003). They also share a constant haploid chromosome number of 18 (Therman, 1956;Kawano et al 1967;Sen 1974;Meng et al, 2005). The unique trimodal karyotype (one long, nine medium-length, and eight small chromosomes) is common in most species in the genus (Kawano and Iltis, 1966;Judd, 2003;Meng et al, 2005), though a few of them are not typical (e.g., a bimodal karyotype in M. tatsienense and unimodal in M. dahuricum and M. atropurpurem; Meng et al, 2005).…”

Chromosomal evolution in Mediterranean species ofOphryssect.Pseudophrys(Orchidaceae): An analysis of karyotypes and polyploidy

“…Chromosome counts provide indispensable information on genetic discontinuities within and among of species, and they contribute to our understanding of phylogenetic relationships at all taxonomic levels (e.g., Semple & al., 1989). Realizing the value of chromosome data for evolutionary studies, systematists have pursued the long-term goal of determining chromosome numbers for as many species and populations as possible (e.g., Greilhuber & Ehrendorfer, 1975;Bianco & al., 1989;Bernardos & Amich, 2002;Bernardos & al., 2003b;Acosta & al., 2005;Meng & al., 2005;Bačič & al., 2007;Amich & al., 2009). However, despite its taxonomic importance, the chromosome numbers of some 75% of all flowering plants remain unknown (Bennett, 1998).…”

Molecular systematics and historical biogeography of Maianthemum s.s.

“…immature berries with purple dots, turning red at maturity, and a nonvariable haploid chromosome number of 18 ( Th erman, 1956 ;LaFrankie, 1986a , b ;Meng et al, 2005 ). Th e members of Maianthemum have oft en been divided into two groups based on fl ower morphology.…”