Grass and Forage Plant Improvement in the Tropics and Sub-Tropics

The majority of tropical and subtropical forage grass genera and/or species have not yet been collected, or need further collection to be representative of their natural distribution. New biotechnological techniques will only result in the release of superior forage cultivars if supported by strong breeding programs. More funding and investment in the formation of strong public research teams in forage conservation and improvement are needed to guarantee the sustainability of tropical and subtropical pasture-based livestock systems in the future. The creation of a permanent international working group on tropical and subtropical forages is essential to assist the International Plant Genetic Resources Institute (IPGRI) in prioritising collection, conservation, evaluation and adoption in the tropical/subtropical world for the benefit of mankind

Grass and Forage Plant Improvement in the Tropics and Sub-Tropics

Key points 1. The majority of tropical and subtropical forage grass genera and/or species have not yet been collected, or need further collection to be representative of their natural distribution. 2. New biotechnological techniques will only result in the release of superior forage cultivars if supported by strong breeding programs. 3. More funding and investment in the formation of strong public research teams in forage conservation and improvement are needed to guarantee the sustainability of tropical and subtropical pasture-based livestock systems in the future. 4. The creation of a permanent international working group on tropical and subtropical forages is essential to assist the International Plant Genetic Resources Institute (IPGRI) in prioritising collection, conservation, evaluation and adoption in the tropical/subtropical world for the benefit of mankind

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