Abstract The objective of this work was to study the inheritance of soybean resistance to Soybean Steam Necrosis (SSN) and to map the resistance gene(s), using an F2 population from the cross between the soybean cultivars BRS 133 (resistant) and CD 206 (susceptible). A phenotypic evaluation was performed under controlled conditions, in a greenhouse. In a population of 114 F2 plants, 92 were resistant, and 22 were susceptible. The result is compatible with the inheritance of one dominant gene (χ2=1.98, P = 15.97%). Analysis of F1 and backcross populations confirmed the inheritance of one dominant gene. Bulk segregant analysis (BSA) was used as the mapping strategy. The resistance gene was mapped on chromosome 18 of the soybean genome, between markers Sat_308 and Satt303. This dominant gene is located on the same chromosome where the recessive SSN resistance gene rbc1 was mapped, at 8cM distance, and was named Rbc2.

RESUMO. O tipo de crescimento da haste da soja é característica diferenciadora de cultivares. Os genes Dt1 e Dt2 afetam a terminação da haste, haja vista que os tipos de crescimento são classificados em determinado, semideterminado e indeterminado. A caracterização fenotípica do tipo de crescimento é complexa e, ocasionalmente, é descrito erroneamente. O objetivo deste trabalho foi mapear e validar marcadores moleculares microssatélites para classificar a soja quanto ao tipo de crescimento, buscando facilitar a descrição de cultivares e a seleção genotípica. Para mapeamento e validação dos marcadores moleculares, foram utilizadas 2 populações F2:3: T 117 (tipo de crescimento semideterminado) x Igra RA 518 RR (tipo de crescimento indeterminado) e CD 235RR (tipo de crescimento determinado) x Igra RA 518 RR. Este estudo evidenciou a associação do marcador molecular ao gene GmTFL1b sendo eficiente na classificação dos tipos de crescimento em soja. O marcador sat_064 está ligado ao gene Dt2, localizado no Grupo de Ligação G do mapa consenso da soja, com frequência de recombinação de 19,4%. Os marcadores moleculares, para os genes Dt1 e Dt2, são eficientes na descrição de genótipos quanto ao tipo de crescimento da haste da soja, bem como para serem utilizados na seleção.

ABSTRACT. The type of stem growth in soybean is a distinguishing feature of cultivars. The genes Dt1 and Dt2 affect the termination of the stem, and the types of growth are classified as determinate, semi-determinate and indeterminate. Phenotypic characterization of the type of growth is complex and is occasionally erroneously described. The objective of this study was to map and validate molecular markers to classify the type of soybean growth to facilitate the description of cultivars and genotypic selection. Two populations were used for mapping and validation of molecular markers F2:3: T 117 (semi-determinate growth type) x Igra RA 518 RR (indeterminate growth type) and CD 235RR (determinate growth type) x Igra RA 518 RR. The study demonstrates that the association of the molecular marker with the gene GmTFL1b was efficient in the classification of soybean growth types. The marker sat_064 is connected to the Dt2 gene, which is located in the Liaison Group G of the consensus map of soybeans with a recombination frequency of 19.4%. Molecular markers for Dt1 and Dt2 genes efficiently described the genotypes of soybean stem growth and selection.

Este trabalho teve o objetivo de avaliar o fluxo gênico em soja, na Região Oeste do Paraná. Foram semeados cinco círculos concêntricos, com a cultivar CD 219RR, que contém o gene CP4 EPSPS. Os círculos foram espaçados em 50 cm, com círculo interno de diâmetro de 50 cm. Externamente a estes, foi semeada a cultivar CD 211 (convencional), também em cinco círculos concêntricos, espaçados em 1 m. As plantas da cultivar CD 211 foram colhidas e trilhadas individualmente, e as sementes semeadas novamente no campo. Após a emergência, foram obtidas 151.772 plântulas, as quais, com 15 dias, foram pulverizadas com 900 g ha-1 de i.a. de glifosato. Após uma semana, plantas sobreviventes foram submetidas à análise de PCR, para verificar a presença do gene CP4 EPSPS. A taxa de fecundação cruzada foi de 0,61, 0,29, 0,23, 0,22 e 0,23% respectivamente a 1, 2, 3, 4 e 5 m de distância das plantas geneticamente modificadas.

The objective of this work was to evaluate soybean gene flow in the Western Region of Paraná. Five concentric circles were sowed with the CD 219RR cultivar, which contains the CP4 EPSPS gene. The circles were spaced in 50 cm and the central circle had 50 cm in diameter. Externally to the CD 219RR circles, five concentric circles were sowed with CD 211 cultivar, a no genetically modified soybean, spaced of 1 m. The CD 211 plants were harvested and threshed separately and the seeds were sowed again. After the emergency, 151,772 seedlings were obtained, which with 15 days were sprayed with 900 g ha-1 a.i. of glyphosate. After one week, the surviving plants were analysed by PCR to verify the CP4 EPSPS gene presence. The cross-pollinating rate was 0.61, 0.29, 0.23, 0.22 and 0.23% in 1, 2, 3, 4 and 5 m distance of the genetically modified plants, respectively.