Avaliação da base genética de genótipos de soja resistentes ao nematóide de cisto (raça 3) por marcadores microssatélites

O presente trabalho objetivou a avaliação da divergência genética entre linhagens e cultivares de soja com resistência ao nematóide de cisto (NCS) através de marcadores moleculares do tipo microssatélite, a fim de identificar genótipos similares e grupos heterogêneos. Foram utilizadas 30 cultivares de soja e 10 genótipos em geração F8, todos resistentes ao NCS. As análises foram realizadas com 12 iniciadores, a saber: Satt185, Satt308, Satt187, Satt070, Satt009, Satt129, Satt154, Satt152, Satt175, Satt045, Satt162 e Satt163. As análises de dissimilaridade foram realizadas através do complemento dos coeficientes de Coincidência Simples e de Rogers e Tanimoto. Os agrupamentos foram realizados pelos Métodos de Otimização de Tocher, Vizinho mais Próximo, Vizinho mais Distante, Ward, Ligação Média Dentro de Grupo, UPGMA e WPGMA. Em adição, foram feitas as projeções no plano bi e tridimensional. Os resultados mostraram coeficientes de dissimilaridade de Coincidência Simples e de Rogers e Tanimoto com médias de 0,36 e 0,5, respectivamente. Foram observados genótipos mais semelhantes e grupos mais divergentes, na maioria das vezes concordando com as respectivas fontes de resistência. Os resultados dos diferentes métodos aglomerativos confirmaram a existência de uma estrutura natural de agrupamento em função da similaridade genética entre os genótipos. Entretanto, o emprego de mais de um método de agrupamento pode ser recomendado devido às diferenças entre as metodologias. Alguns métodos mais comumente utilizados como o Vizinho Mais Distante, Ward, WPGMA e UPGMA foram considerados adequados ao agrupamento de genótipos no presente estudo, apresentando coincidência de resultados, inclusive em relação às genealogias dos genótipos analisados. As projeções no plano...The present work aimed the evaluation of the genetic divergence among soybean lines and cultivars, resistant to cyst nematode (NCS). Therefore microsatellite molecular markers were used, with the objective of identify similar genotypes and heterogeneous groups. There were used 30 soybean cultivars and 10 genotypes in F8 generation, all of them resistant to NCS. The analyses were made using 20 primers (Satt185, Satt308, Satt187, Satt070, Satt009, Satt129, Satt154, Satt152, Satt175, Satt045, Satt162 and Satt163). The dissimilarity analyses were made through the complement of Simple Coincidence and Rogers and Tanimoto Coefficients. Clusters were performed by the following methods: Tocher Optimization, Single Linkage, Complete Linkage, Ward, Average Link Within a Group, UPGMA and WPGMA. In addition, the bi and tridimensional plan projections were made. The results showed average values of 0,36 and 0,5 in the Simple Coincidence and Rogers and Tanimoto dissimilarity coefficients, respectively. Most similar genotypes and most divergent groups were found, usually according to the respective resistant sources. Results of the different cluster methods confirmed a group’s structure according to genotypes similarity. However, the use of many clustering methods should be recommended, because of their methodology differences. Some of the most used methods, like Complete Linkage, Ward, WPGMA and UPGMA, were considered adequate for clustering the genotypes in this case. There were observed coincidence of results confirming the genotypes genealogies. The plan projections were not satisfactory for these analyses, showing high distortion and stress. The results combination can be useful in the parental choice for crosses of Soybean Breeding Programs.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Validation of microsatellite markers for assisted selection of soybean genotypes resistant to powdery mildew

Powdery mildew is one of the most serious diseases of soybean and is found in all producing countries. The purpose of this study was to validate microsatellite markers previously identified as associated with resistance to powdery mildew in soybean. The study was conducted in two F, parent populations with contrasting resistance to powdery mildew, In the analysis 10 SSR primers were used for the populations. and tour polymorphic markers were identified for cross I (MGBR95-20937 x IAC-Foscarin 31) and three for cross 2 (MGBR-46 x Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) 48). The Chi-square analysis of the phenotypic evaluation confirmed the expected segregation (3: 1) of a dominant gene related to resistance. The polymorphic markers also segregated as expected (1:2:1). The markers Sat 366 and Sat 393 in the crosses 1 and 2. respectively, located at 9.41 and 12.45 cM from the gene. were considered promising for marker-assisted selection for resistance to powdery mildew in soybean. at a selection efficiency of 92.7% and 60.3% respectively