Unusual chromosome numbers in Paspalum L. (Poaceae: Paniceae) from Brazil

Abstract

ABSTRACT. Somatic chromosome numbers were determined for 20 new germplasm accessions of Paspalum, belonging to 17 species collected in Brazil. Chromosome number is reported for the first time for P. reduncum (2n = 18), P. cinerascens (2n = 20), P. cordatum (2n = 20), P. filgueirasii (2n = 24), P. ammodes (2n = 36), P. bicilium (2n = 40), P. heterotrichon (2n = 40), and P. burmanii (2n = 48). New cytotypes were confirmed for two germplasm accessions of P. carinatum (2n = 30) and P. trachycoleon (2n = 36), one of P. clavuliferum (2n = 40) and one of P. lanciflorum (2n = 40), indicating variability in these species. The remaining chromosome numbers reported here confirm previous counts. The unexpected chromosome numbers 2n = 18, 24, 36, and 48 in Paspalum species, which are usually shown to be multiples of 10, suggest that much more collection and cytogenetic characterization are necessary to assess the whole chromosomal and genomic multiplicity present in the genus, which seems to be much more diverse than currently thought to be.

Chromosome numbers and ploidy levels of Paspalum species from subtropical South America (Poaceae)

“…ex Flüggé (Selva 1976;Reeder 1984). Recently, Peñaloza et al (2008), have reported chromosome numbers of five species with unexpected 2n = 18, 24, 36, and 48, which could be multiple to x = 6 or x = 9.…”

“…Chromosome numbers are known for nearly half the species (Honfi 2003). The basic chromosome number is generally x = 10, with a few exceptions (Honfi et al 1990;Quarin 1992;Norrmann et al 1994a;Pozzobon et al 2000;Peñaloza et al 2008). Polyploidy is a very common feature present in about 80% of the species, with levels varying from 3x to 16x and tetraploidy the most frequent condition.…”

“…Efforts to obtain chromosome counts of new accessions of Paspalum are justified because new chromosome races continue to be discovered (Honfi et al 1990;Norrmann et al 1994a;Pozzobon et al 2000Pozzobon et al , 2008Pozzobon and Valls 2003;Morrone et al 2006;Peñaloza et al 2008), and because they also provide information about (i) ploidy level, (ii) preliminary assumptions about modes of reproduction, and (iii) the geographic distribution of chromosome races. The objective of this work is to provide a first step of cytogenetic characterization of Paspalum accessions from subtropical South America, based on chromosome numbers and ploidy levels.…”

<I>Paspalum minutispiculatum</I> (Poaceae, Panicoideae): a New Annual Species from Central Brazil

“…2D-E, 3D) suggest that P. minutispiculatum is morphologically closer to P. bicilium (Figs. 3C-right, E), according to the circumscription of the latter species as cited by Filgueiras (1991), Oliveira and Valls (2014), and supported by Peñaloza et al (2008), and not as a mere synonym of P. polyphyllum (Silva 2013). On the other hand, P. minutispiculatum differs from P. bicilium and P. polyphyllum by several characters (Fig.…”

“…Killeen (1990), Denham et al (2002), and Zuloaga and Morrone (2005) considered P. bicilium as conspecific with P. polyphyllum. Filgueiras (1991), Peñaloza et al (2008), Silva (2013), and Oliveira and Valls (2014) considered P. bicilium and P. polyphyllum independent species. Rua et al (2010) found evidence with molecular data that these species are distinct.…”