title: High degree of genetic diversity among genotypes of  the forage grass Brachiaria ruziziensis (Poaceae) detected with ISSR  markers.
abstract: The grasses of the genus Brachiaria account for  80% of the cultivated pastures in Brazil. Despite its importance for livestock  production, little information is available for breeding purposes. Embrapa has  a population of B. ruziziensis from different regions of Brazil,  representing most of existing variability. This population was used to initiate  an improvement program based on recurrent selection. In order to assist the  genetic improvement program, we estimated the molecular variability among 93  genotypes of Embrapa's collection using ISSR (inter-simple sequence repeat)  markers. DNA was extracted from the leaves. Twelve ISSR primers generated 89  polymorphic bands in the 93 genotypes. The number of bands identified by each  primer ranged from two to 13, with a mean of 7.41. Cluster analysis revealed a  clearly distinct group, containing most of the B. ruziziensis genotypes  apart from the outgroup genotypes. Genetic similarity coefficients ranged from  0.0 to 0.95, with a mean of 0.50 and analysis of molecular variance indicated  higher variation within (73.43%) than among species (26.57%). We conclude that  there is a high genetic diversity among these B. ruziziensis genotypes,  which could be explored by breeding programs.
authors.affiliation: Embrapa Gado de Leite, Juiz de Fora, MG, Brasil. azevedo@cnpgl.embrapa.br
authors.forename: A L S
authors.initials: AL
authors.lastname: Azevedo
authors.forename: P P
authors.initials: PP
authors.lastname: Costa
authors.forename: M A
authors.initials: MA
authors.lastname: Machado
authors.forename: C M P
authors.initials: CM
authors.lastname: de Paula
authors.forename: F S
authors.initials: FS
authors.lastname: Sobrinho
mesh_terms: D035201:Brachiaria / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D018895:Microsatellite Repeats / Q000235:genetics*; D010802:Phylogeny
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers