Genetic diversity in red clover (Trifolium pratense L.) revealed by morphological and microsatellite (SSR) markers |
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Authors: | Paula Menna Barreto Dias Bernadette Julier Jean-Paul Sampoux Philippe Barre Miguel Dall’Agnol |
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Institution: | (1) Departamento de Plantas Forrageiras e Agrometeorologia, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Caixa Postal 15100, 91501-970 Porto Alegre, RS, Brazil;(2) INRA, Unité de Génétique et d’Amélioration des Plantes Fourragères, BP6, 86600 Lusignan, France |
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Abstract: | The NPGS-USDA core collection with 85 accessions of red clover, an important forage species, is little described. The goal
of the present study was to evaluate the diversity of a set of accessions from the core collection at the morphological and
molecular level in order to extract some valuable accessions for Brazilian red clover breeding programs. Twenty-one morphological
traits, collected in field and greenhouse in South Brazil, and seven SSR markers were used to describe 57 accessions from
the U.S. core collection and one population cultivated in Southern Brazil. Variation between accessions was large for most
of the 21 morphological traits. A cluster analysis based on the morphological traits revealed five distinct clusters that
separated the populations according to flowering earliness, as already described, but also according to persistency, growth
habit and dry matter productivity. Over seven SSR loci, the number of alleles averaged 11.1 alleles per locus. Genetic diversity
measured with SSR markers was high, with a mean expected heterozygosity of 0.86. An analysis of molecular variance revealed
that the largest proportion of variation (83.6%) resided at the within population level. Although the molecular markers also
separated accessions into five clusters, there was no coincidence between the composition of groups found with morphological
and molecular data. Use of genetic diversity in breeding programs requires to use the most promising populations, to combine
positive traits such as persistency and forage yield, and probably to use within population variation to detect valuable genotypes
that could be used as parents of synthetic varieties. |
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Keywords: | Cluster analysis Genetic diversity Microsatellite Morphological traits Red clover Trifolium pratense |
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