Genetic relationship among paspalum species of the subgenus anachyris : taxonomic and evolutionary implications
Fecha
2014-10Autor
Zilli, Alex Leonel
Hojsgaard, Diego Hernán
Brugnoli, Elsa Andrea
Acuña, Carlos Alberto
Honfi, Ana Isabel
Urbani, Mario Hugo
Quarin, Camilo Luis
Martínez, Eric Javier
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Paspalum is one of the most important genera of the Poaceae family due to its large number of species and
diversity. The subgenus Anachyris comprises six species mainly from South America grouped together by
sharing rare spikelet characteristics. A genetic analysis using ISSR markers, compared with the morpho logical and phenotypic variation observed in each one species, was used to establish genetic relationships
among 40 accessions with several ploidy levels, belonging to 5 species ofthe subgenus Anachyris. Fourteen
accessions of Paspalum malacophyllum (2x and 4x), 12 of P. simplex (2x, 3x, 4x and 6x), 4 of P. procurrens
(2x and 4x), 4 of P. usterii (4x) and 6 of P. volcanensis (4x) were analysed. A total of 227 ISSR loci (98.7%
polymorphic) were detected among all accessions, with variable loci number and percentages of poly morphism according to species delimitations. Six main groups were identified by cluster analysis based
on Jaccard’s genetic distance and UPGMA, four of which matched all the respective accessions of P. sim plex, P. procurrens, P. usterii and P. volcanensis, while the other two were consistent with two different
groups of accessions of P. malacophyllum, one involving most tetraploid accessions, and the other one
grouping together a tetraploid and two diploid accessions. The distinctive morphological characteristics
and the separate clustering ofthese tetraploid and diploid cytotypes suggestto consider a new multiploid
species complex inside the subgenus Anachyris. Both cytotypes of P. procurrens, and the four co-specific
cytotypes of P. simplex consistently clustered together forming two specific groups for the two multi ploid taxons. This is in agreement with the existence of high phenotypic similarities between diploid and
tetraploid cytotypes of P. procurrens, and among diploid, triploid, tetraploid and hexaploid cytotypes of
P. simplex. Since the polyploid cytotypes of these species are reproduced by apomixis, the specific genetic
clustering by ISSR markers and morphological and cytological results support the hypothesis that the
two multiploid species were originated by autopolyploidy. Our results confirm previous studies suggest ing a monophyletic origin for the subgenus Anachyris and are concordant with previous data regarding
genomic homologies and phylogenetic analyses in the genus.
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