Preliminary Performance of \u3cem\u3ePanicum Maximum\u3c/em\u3e Accessions and Hybrids in Brazil

Due to the lack of high quality forages adapted to the distinct ecosystems in Brazil, a national network to evaluate 14 accessions, 4 hybrids and 5 commercial standards of Panicum maximum was established in 2002, in 5 regions of Brazil (states of Mato Grosso do Sul, Acre, Rondônia, Minas Gerais and in the Federal District). Staff of the Embrapa Beef Cattle group co-ordinated the network and pre-selected the accessions and hybrids (Jank, 1995; Jank et al., 2001; Resende et al., 2004). We present their performance as to leaf dry matter yield (LDMY) and leaf percentage (LP) obtained from 7 harvests in 2003-2004 in Mato Grosso do Sul

Construction of Microsatellite-Enriched Libraries for Tropical Forage Species and Characterization of the Repetitive Sequences Found in \u3cem\u3eBrachiaria Brizantha\u3c/em\u3e

The Brazilian cattle herd comprises 185 million animals fed with about 177 million hectares of native and cultivated pastures (IBGE, 2002). Of the grass species used for forage in Brazil, the African genus Brachiaria is the most widely planted, followed by Panicum, which also has an African origin. Legumes of the Stylosanthes genus, native to the South America, have emerged in the last few years as potential forage species for use with the grasses. These forage species have been bred at Embrapa Beef Cattle and the breeding programs have shown the need for more genetic information including the use of molecular markers. The objectives of this work were to construct microsatellite-enriched genomic libraries for 5 species of Brachiaria (B. brizantha, B. decumbens, B. dictioneura, B. humidicola and B. ruziziensis), for P. maximum and for S. capitata, and to characterize the microsatellites found in B. brizantha

Molecular Genetic Variability, Population Structure and Mating System in Tropical Forages

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyse population structure and genetic diversity, evolution and origin of the genetic variability in the centre of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work

Avaliação genética em erva-mate pelo procedimento BLUP individual multivariado sob interação genótipo x ambiente Genetic evaluation in Ilex paraguariensis by the multivariate individual BLUP procedure with genotype-environment interaction

Os objetivos deste trabalho foram estimar parâmetros genéticos e fenotípicos e realizar a predição de valores genéticos de matrizes e procedências de erva-mate (Ilex paraguariensis). Foram avaliadas 164 progênies de oito procedências, em três locais (Ivaí, PR, Guarapuava, PR e Rio Azul, PR), em relação ao caráter produção de massa foliar (PMF). Os componentes de variância, parâmetros genéticos e valores genéticos foram estimados pelo procedimento REML/BLUP individual (máxima verossimilhança restrita/melhor predição linear não viciada), realizando a análise multivariada para os três locais. Os coeficientes de herdabilidade individual, no sentido restrito, para o caráter PMF foram 0,15 em Ivaí, 0,62 em Guarapuava e 0,23 em Rio Azul. A baixa magnitude desses coeficientes em Ivaí e Rio Azul demanda a utilização de métodos de seleção que utilizem todos os efeitos aleatórios do modelo estatístico. O efeito de procedências foi significativo em Ivaí e Rio Azul, com correlação fenotípica intraclasse de 0,13 em Ivaí e de 0,09 em Rio Azul. As procedências apresentaram correlação genética de 0,95 entre os locais Ivaí e Rio Azul. Nesses locais, as procedências foram mais estáveis nos diferentes ambientes do que as progênies. Foram preditos os valores genéticos em relação a todas as procedências e matrizes em todos os locais quanto ao caráter avaliado. As melhores procedências são Barão de Cotegipe, Quedas do Iguaçu, Cascavel e Ivaí.<br>The objectives of this paper were to estimate genetic and phenotypic parameters and to predict breeding values for parents and provenances of Ilex paraguariensis. Eight provenances with 164 progenies were evaluated on three sites (Ivaí, PR, Guarapuava, PR and Rio Azul, PR) for the trait leaf weight (LW). All the variance components, parameters and breeding values were obtained by REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) procedure at the individual level, through multivariate analysis involving the three sites. The individual strict sense heritabilities for the trait LW were 0.15 in Ivaí, 0.62 in Guarapuava and 0.23 in Rio Azul, demanding more sophisticated selection methods in Ivaí and Rio Azul. The provenance effect was significant in Ivaí and Rio Azul, with intraclass phenotypic correlation of 0.13 in Ivaí and 0.09 in Rio Azul. The provenances were more stable across sites than progenies with genetic correlation of 0.95 between the sites Ivaí and Rio Azul. Genetic values for all provenances and parents in all sites were predicted for the trait LW. The best provenances are Barão de Cotegipe, Quedas do Iguaçu, Cascavel and Ivaí

Molecular genetic variability, population structure and mating system in tropical forages

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyze population structure and genetic diversity, evolution and origin of the genetic variability in the center of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work