A. E. Pipolo

New genes conferring resistance to Asian soybean rust: allelic testing for the Rpp2 and Rpp4 loci

The objective of this study was to conduct allelic tests including crosses between a group of rust resistant genotypes from Embrapas soybean germplasm collection and PI 230970 and PI 459025, which carry the Rpp2 and Rpp4 genes, respectively. Asian Soybean rust (ASR) caused by the fungus Phakopsora pachyrhizi has resulted in significant yield losses and concern among Brazilian farmers. Until recently, there were four resistance genes (Rpp1 through Rpp4) described in the literature, but only Rpp2 and Rpp4 are still effective in Brazil. Twenty-six sources of resistance to P. pachyrhizi were crossed with PI 230970 and PI 459025 (Rpp2 and Rpp4 gene sources, respectively) and plants of their F2 generations were infected with a suspension containing 2.5x104 spores per milliliter and assessed in a greenhouse after 20 days, for the presence of resistant (RB) or susceptible (TAN) lesions. Chi-square tests were applied to investigate the hypotheses of independent or allelic resistance gene segregations. ASR resistant genes derived from PI 197182, PI 230971 and PI 417125 did not segregate in crosses with PI 230970, which indicates that these genotypes have a single resistance gene in the Rpp2 locus. Crosses with the other 23 genotypes resulted in segregating populations, suggesting that their resistance genes do not belong to Rpp2 or Rpp4 loci.

Identification of QTLs associated with limited leaf hydraulic conductance in soybean

Soybean (Glycine max (L.) Merr.) genotype PI 416937 has been identified as expressing a ‘slow-wilting’ phenotype in the field and this has been traced to a low hydraulic conductance in its leaves. The transpiration rate of de-rooted shoots of this genotype has been found to be insensitive to the aquaporin inhibitor silver nitrate compared to elite cultivars which are silver nitrate sensitive. These results indicated that PI 416937 might have a unique aquaporin population. The objective of this study was to determine if QTLs could be identified that are associated with the lack of sensitivity in PI 416937 to silver. To identify the genomic locations and genetic bases of this trait, a recombinant inbred line population was derived from a mating between PI 416937 and the cultivar ‘Benning’. The RILs were all phenotyped for their response to the silver inhibitor and the results were subjected to a QTL analysis. Four QTL were identified as putatively associated with the silver response (qSV). These QTL explained from 17.7 to 24.7% of the phenotypic variation with qSV_Gm12 explaining the greatest amount of phenotypic variation. The qSV_Gm03 and qSV_Gm10 QTL inherited their positive alleles from PI 416937, while qSV_Gm05 and qSV_Gm12 inherited their favorable alleles from Benning. Co-localized silver nitrate response QTL with other morpho–physiological traits could help to explain soybean plant’s ability to tolerate water-deficit stress.

Interação genótipo-ambiente de soja convencional e transgênica resistente a glifosato, no Estado do Paraná

Os objetivos deste trabalho foram: comparar a produtividade e a adaptacao de genotipos de soja convencional e de soja transgenica resistente ao herbicida glifosato, de diferentes grupos de maturacao, desenvolvidos pelo programa de melhoramento da Embrapa Soja para o Estado do Parana; estudar a importância relativa dos efeitos de local, ano, cultivar e suas respectivas interacoes; e verificar a possibilidade de se estratificar o Estado em regioes mais homogeneas, para reduzir o numero de locais nos ensaios de competicao de linhagens. Foram utilizados dados de produtividade de graos de ensaios regionais, no Estado do Parana, entre 2001 e 2005. O delineamento experimental utilizado foi o de blocos ao acaso. A possibilidade de se realizar a estratificacao do Estado em regioes mais homogeneas e de descarte de locais foi verificada pela significância da interacao genotipo x ambiente entre locais. Nao houve diferenca significativa de produtividade entre a soja convencional e a transgenica, independentemente do grupo de maturacao. O efeito de local foi mais importante que o efeito de ano, na composicao dos ambientes. A estratificacao do Estado do Parana em regioes nao trouxe vantagens, nos anos analisados, para os testes de linhagens; apenas os locais da regiao Sul mostraram algum grau de similaridade entre si.

Soybean parent selection based on genetic diversity.

Thirty-four soybean lines were assessed for twelve traits. The genetic distances were estimates using multivariate techniques, to identify parents to be included in breeding programs for hybridization. Grouping by the Tocher method, from generalized Mahalanobis distances, divided the 34 lines into four groups. The most important agronomic traits, weight of seeds per plot, plant height, height of first pod and days to maturity were considered when recommending for crossing. The following crosses were recommended based on the genetic divergence and the key agronomic traits: lines 23, 10, 2, 27 and 25 (group I) with genotype 6 (group II) and genotype 16 (group III). Thus only ten crosses would be made, representing only 2% of the total crosses which could be made in the partial diallel among the 34 lines assessed, which would allow up to 561 combinations.

Influence of genotype on protein and oil concentration of soybean seeds

Com o objetivo de avaliar a influencia do genotipo sobre as concentracoes de proteina e oleo, sementes imaturas das cultivares de soja CD 202 e CD 206 foram retiradas da planta mae no estadio R5, cultivadas in vitro em meio de cultura liquido por oito dias, contendo 20, 40 e 60 mM de glutamina. Depois disso, as concentracoes de oleo e proteina foram comparadas com as das sementes que continuaram seu desenvolvimento in vivo. Com a maior disponibilidade de glutamina para a semente, houve um aumento do conteudo proteico nas sementes. Quanto as concentracoes de proteina, os genotipos foram estatisticamente diferentes, levando a afirmar a sua influencia na concentracao de proteina na semente. As concentracoes de proteina e oleo foram inversamente relacionadas quando variou a concentracao de glutamina.

TRANSFERÊNCIA DE TECNOLOGIA PARA CULTIVARES DE SOJA DESENVOLVIDAS PELA EMBRAPA SOJA PARA O PARANÁ 1

During the 1990/1991 growing season, Embrapa Soybean and Embrapa Technology Transfer started a joint program of technology transfer for soybean cultivars with seed producers. The methodology used consisted of planning the activities of technology transfer, establishment and management for demonstration units, field follow-ups, implementation of field days, and evaluation of the activities therein developed, with the participation and feedback provided during all the steps by the seed producers engaged in the program. This work carried out with the Embrapa soybean-breeding program and in synchrony with the seed production sector resulted in Embrapas cultivars sharing an average of 50% of the total soybean seeds produced in the State of Parana, starting with 3% in 1990 and reaching 64% in 2003. The results achieved clearly show the importance of incorporating technology transfer into plant breeding research projects.

Metodologias para obtenção de resistência e/ou tolerância da soja à ferrugem-asiática

ABSTRACT A soja ( Glycine max (L.) Merrill) e a cultura com a maior areacultivada no Brasil. Na safra de 2010/2011 a area cultivada foi de24,17 milhoes de hectares, seguida pelo milho com 13,29 milhoes dehectares e pela cana-de-acucar com 8,03 milhoes de hectares (6). OBrasil e o segundo produtor mundial de soja, sendo responsavel poraproximadamente 27,7% da producao mundial (22).A ferrugem-asiatica ( Phakopsora pachyrhizi Syd. e P. Syd.) foidetectada pela primeira vez no Brasil no final da safra 2000/01. Nasafra 2001/02 foi relatada nas principais regioes produtoras, desde oRio Grande do Sul ate o Mato Grosso, onde nos casos mais severos,as perdas atingiram ate 70% (25). Na safra seguinte espalhou-se empraticamente todas as regioes produtoras, representando uma ameacapara a cultura em funcao dos prejuizos causados e do aumento docusto de producao para seu controle (8).O uso de cultivares resistentes e/ou tolerantes e o metodo decontrole mais eficiente e barato para os produtores, alem de ser o maisadequado as praticas de conservacao do ambiente. Devido ao fungo