Chromosome Numbers of Some Southernmost Species of Mimosa L. (Leguminosae).

Abstract

Summary Chromosome numbers of 9 species of Mimosa which grow in the southern limit of the South American centre of diversification were determined, all of them are new reports except the one of M. oligophylla. M. vellosiella, M. oligophylla and M. flagellaris were diploids with 2n=2x=26; M. velloziana and M. adpressa were tetraploids with 2n =4x= 52; M. sprengelii, M rarnulosa and M. rocae were octoploids with 2n -8x=104; and one accession of M. balansae was diploid while the other was tetraploid. All of them were multiples of the basic chromosome number x=13. The polyploid species were more frequent at higher latitudes, this increment was also accompanied with a higher ploidy level of the polyploids southernward. All the polyploids found belong to the sections with most advanced characters of the genus, which supports the phylogeny proposed for Mimosa by Barneby. Data suggest that the extension of the genus toward the temperate zones might have be done mainly by polyploid species, which may have had advantages over the diploids in colonising habitats restricted to the latter.

Chromosome number variation and evolution in Neotropical Leguminoseae (Mimosoideae) from northeastern Brazil

“…These authors observed that 26% of the species analyzed were polyploids and that at least 3 of them exhibited intraspecific polyploidy. A similar evolutionary pattern of polyploidy was also observed in other South America species of Mimosa (Seijo and Fernández, 2001) and Leucaena (Boff and Schifino-Wittmann, 2003). A total of 13 species of the genus Inga from northeastern Brazil were analyzed, and 4 were found to be polyploids (2 of them showing intraspecific polyploidy; Mata, 2009, unpublished data).…”

Cytogenetics of Mimosa bimucronata (DC.) O. Kuntze (Mimosoideae, Leguminosae): chromosome number, polysomaty and meiosis

“…Most of Mimosa species studied (around 10 % of the genus) are diploid, with 2n = 2x =26, others are tetraploid (2n = 4x = 52) and a few are octaploid (2n = 8x = 104) (Federov 1969, Alvez and Custódio 1989, Seijo 1993, 1999, 2000, Seijo and Fernández 2001, Goldblatt and Johnson 2009 (Morales et al 2010). It should be stressed that most chromosome counts are restricted to one or fewer populations, therefore intraspecific variability may be more common than reported.…”

Polyploidy, B chromosomes, and heterochromatin characterization of Mimosa caesalpiniifolia Benth. (Fabaceae-Mimosoideae)

“…In the genus Mimosa, cytogenetic studies have been done mainly using conventional staining (Isely 1971;Lewis and Elias 1981;Goldblatt 1981;Seijo 1993Seijo , 1999Seijo , 2000Seijo and Fernández 2001;Morales et al 2007Morales et al , 2010Morales et al , 2011Dahmer et al 2011). In spite of the great number of papers published about the genus, the small size of the chromosomes within Fabaceae family (Biondo et al 2005) has hindered elucidation of the morphological features of the chromosomes (Morales et al 2010).…”