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

Abstract

Somatic chromosome numbers of 131 accessions belonging to 55 Paspalum species from subtropical South America have been determined. All species had x = 10 as a basic chromosome number, except P. almum which had x = 6. Six ploidy levels were found among species with tetraploidy as the most frequent condition. New diploid and octoploid counts were reported. For Paspalum lilloi and P. glabrinode (both 2n = 2x = 20), and for P. ellipticum, P. erianthoides, P. ovale and P. remotum (all 2n = 8x = 80) sporophytic chromosome numbers are presented for the first time. Records that differ from previously reported counts are given for the following species: P. paucifolium (2n = 2x = 20), P. ceresia (2n = 6x = 60), P. conjugatum (2n = 6x = 60), P. alcalinum (2n = 6x = 60) and P. aff. arundinellum (2n ? 1 = 5x ? 1 = 51). These chromosome data are discussed in light of ploidy-level variation and implications for breeding systems within and among species.

Cytological and reproductive aspects in the Caespitosa group of Paspalum

“…The Brazilian accessions of Paspalum chacoense and P. indecorum are diploid, with 2n=2x=20 chromosomes, in agreement with previously published reports (FERNANDES et al, 1974;QUARÍN, 1977;QUARÍN & BURSON, 1983;BURSON, 1985;PAGLIARINI et al, 2001;HOJSGAARD et al, 2009). Both species reproduce sexually (BURSON, 1985;QUARÍN & BURSON, 1983).…”

“…In line with additional papers that cover a broader sampling, both in terms of accessions and geographical sites of origin of available Paspalum germplasm (HONFI et al, 1990;POZZOBON et al, 2000;MORRONE et al, 2006;HOJSGAARD et al, 2009), they document the fi nding of more than a single ploidy level in distinctive accessions of same species.…”

“…Previous information has been published for Paspalum chacoense and P. indecorum only (FERNANDES et al, 1974;QUARÍN, 1977;QUARÍN & BURSON, 1983;BURSON, 1985;PAGLIARINI et al, 2001;HOJSGAARD et al, 2009). Basic chromosome number of these two sexual, diploid, 2n=20 species is x=10.…”

Microsporogenesis in Paspalum conspersum Schrad. (Virgata group) with different ploidy levels

“…Previous tetraploid (2n = 4x = 40) reports for P. conspersum, associated with regular meiosis and sexual reproduction (Fernandes et al, 1974;Burson and Bennett, 1976), do not, in fact, refer to this species. On the contrary, hexaploidy (2n = 6x = 60) has been most commonly reported for true representatives of the species (Quarín, 1977;Quarín and Hanna, 1980;Pozzobon and Valls, 1987;Honfi et al, 1990;Pagliarini et al, 2001;Adamowski et al, 2005;Pozzobon et al, 2000Pozzobon et al, , 2008Hojsgaard et al, 2009). The 60-chromosome race of P. conspersum analyzed by Quarín and Hanna (1980) showed regular meiosis, with primarily bivalent pairing and a low percentage of univalents and quadrivalents.…”

“…(Bonilla and Quarín, 1997), P. alcalinum Mez (Burson, 1997), P. dilatatum Poir. (Mehra and Chaudhary, 1981;Burson et al, 1991;Pozzobon et al, 2000), P. arundinellum Mez (Hojsgaard et al, 2009), and P. notatum Flüggé (Tischler and Burson, 1995).…”