Abstract Advances in genotyping technologies have transformed the way breeding programs manage their genetic resources. The identification of single nucleotide polymorphisms (SNPs) can improve understanding of the genetic diversity of maize (Zea mays) inbred lines and their classification into heterotic groups, which is useful in determining certain crosses to obtain hybrids with higher yield performance. The genetic diversity of 293 inbred lines was investigated with 5252 SNPs with minor allele frequency (MAF)>5%. There was an average of 525 SNPs per chromosome. Polymorphism information content (PIC) averaged 0.297. The unweighted pair group method with arithmetic mean analysis (UPGMA) and principal component analysis (PCA) based on the genetic distance matrix revealed four similar clusters and high cophenetic correlation coefficients (0.953 and 0.863, respectively). The results showed consistency between genetic distance-based grouping and the heterotic groups previously established using pedigree and topcross information for the inbred lines studied.

A enzima ∆¹-pirrolina-5-carboxilato sintetase (P5CS), codificada pelo gene p5cs, é o passo limitante da biossíntese de prolina, que age como um osmoprotetor. O lançamento de variedades comerciais transgênicas depende da caracterização fisiológica e fenotípica de eventos. O objetivo deste estudo foi avaliar cinco eventos (591, 14, 326, 164, 312) contendo o gene p5cs, através de análises fisiológicas e taxas de produção sob estresse hídrico. Plantas de eventos e controles irrigados e estressados (CI e CS) em estádio de florescimento foram submetidos a 16 dias de restrição hídrica. Foram avaliados: teor relativo de água (RWC); concentração de malondialdeído (MDA%); índice de estabilidade da membrana (MSI%); conteúdo de prolina; e taxas de produção. Como resultado, o efeito do estresse hídrico só foi percebido após 12 dias de restrição hídrica com uma diminuição nos valores de RWC. Plantas transgênicas apresentaram maiores níveis de prolina no 16º dia, comparado ao SC (33 a 62%). Os teores de MDA foram menores no 12º e 16º dias para todas as plantas avaliadas, mas os MSI foram semelhantes ao IC para os eventos 591, 326 e 164, demonstrando o efeito osmoprotetor. Porém, níveis altos de prolina não resultaram em maiores taxas de produção de grãos.

The enzyme ∆¹-pyrroline-5-carboxylate synthetase (P5CS), encoded by the p5cs gene, is the rate-limiting step for proline biosynthesis, which acts as an osmoprotectant. The launch of transgenic commercial varieties depends on physiological and phenotypic characterization of events. The objective of this study was to evaluate five p5cs gene events (591, 14, 326, 164, 312), through physiological analyses and production rates during droughts. Plants of events and irrigated (IC) and stressed controls (SC) in flowering stage were submitted to 16 days of complete water restriction. The following elements were evaluated: relative water content (RWC); malondialdehyde concentration (MDA%); membrane stability index (MSI%); proline content; and production rates. As a result, the effect of water stress was only perceived after 12 days of water restriction with a decrease in the RWC values. Transgenic plants showed higher proline levels on the 16th day, compared to the SC (33 to 62%). The levels of MDA were lower on the 12th and 16th days for all the plants evaluated, but the MSI were similar to the IC for the events 591, 326, and 164, demonstrating the osmoprotectant effect. However, higher levels of proline did not result in higher production rates in the transgenic plants.

Abstract This work aimed to develop and validate individual SNP molecular markers previously identified in a genetic association study of resistance to Meloidogyne incognita in soybean using a microarray panel. The markers identified in the array were converted in single TaqMan® markers. The single markers were used to create an SNP genotyping protocol and establish a marker-assisted selection (MAS) routine associated with resistance to M. incognita in soybean. Out of the eight TaqMan® assays tested, three were validated for use in MAS. The MAS protocol developed in this study uses sequential selection. Initially, molecular markers are used to identify susceptible plants; subsequently, the phenotypic evaluation of plants expressing resistance genotype for the markers is carried out, resulting in the accurate identification of resistant plants. The accuracy of this approach for MAS sequential for M. incognita varied from 94 to 96%.

Abstract Phytophthora root and stem rot is one of the most aggressive diseases in soybean crop. The use of resistant cultivars is the main strategy to reduce losses caused by the pathogen. This study aims to identify SNP markers associated with genes or QTLs that provide soybean with partial resistance to Phytophthora sojae. A total of 169 soybean cultivars were inoculated with Phytophthora sojae and genotyped with 3,807 SNP markers. Genome-wide association analysis was carried out via multiple linear models, followed by multiple linear regression and linkage disequilibrium analysis. Four QTLs associated with the characteristic were identified: two on chromosome 3 and two on chromosome 15. The regions containing these QTLs contain genes already annotated as providers of resistance to pathogens, in plants. The use of those markers in the selection of resistant plants can increase the efficiency of breeding programs in the development of soybean varieties resistant to P. sojae.

Abstract The aim of this study was to evaluate the genetic diversity of the wheat germplasm using high-density genotyping with SNP markers. A set of 211 wheat varieties genotyped with 35,142 SNP markers were used in the experiment. Genetic distances ranged from 0.013 to 0.471, with the highest frequency of distances varying between 0.31 and 0.40. In the cluster analysis by the UPGMA method, 81% of the varieties were clustered in three groups. Genetic variability in the Brazilian wheat germplasm has remained constant for over 70 years. Mean genetic distances among the varieties developed in each decade ranged from 0.33 to 0.34. A trend of genetic distance between genotypes from different eras has been observed over time as a result of breeding. Results described in this study can help Brazilian wheat breeders to manage more adequately genetic variability in the Brazilian wheat germplasm.

Abstract CD 1705 is a cultivar indicated for the wheat-producing regions 1, 2 and 3 of the states of Rio Grande do Sul, Santa Catarina and Paraná. It is appropriate for biscuit manufacturing, has good plant health and high production potential (mean yield of 4308 kg ha-1).

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.

Abstract The aim of this study was to develop a methodology that uses water deficit induction to increase the frequency of hybrids in Citrus varieties that have a high and an intermediate level of polyembryony, respectively. The experiment examined the ‘Sunki Tropical’ mandarin and ‘Rangpur Santa Cruz’ lime genotypes at three water stress intensities: 20, 40 and 100% of the pot capacity (PC). The generated fruits were harvested, and the seeds were counted. After germination, the number of nucellar and hybrid seedlings was determined. For ‘Rangpur Santa Cruz’ lime genotype, the highest hybrid frequency generated was 64.2%, which occurred at a PC of 40% and exceeded by 12% that occurring at a PC of 100%. For ‘Sunki Tropical’ mandarin, the highest observed hybrid frequency was 21.75%, which occurred at a PC of 20% and was more than double the hybrid frequency of 8.57% observed at 100% of the PC.

Abstract CD 1303 is a cultivar indicated for the wheat-producing regions 1, 2 and 3 of the states of Rio Grande do Sul, Santa Catarina and Paraná. It has an early cycle, a short stature and high productive potential (mean of 4311 kg ha-1).

RESUMO. O presente estudo objetivou piramidar genes de resistência à FAS por meio da seleção assistida por marcadores (SAM) microsatélites (SSR), demonstrando os passos para a piramidação. Para obter a primeira geração de piramidação de genes, realizaram-se cruzamentos entre as plantas introduzidas (PI’s), que possuem os genes Rpp1, Rpp2, Rpp3, Rpp4 e Rpp5. As plantas F1 dos cruzamentos iniciais foram cruzadas para obter plantas com os quatro genes de resistência (segunda geração de piramidação). As plantas selecionadas desta segunda geração foram novamente cruzadas (terceira geração de piramidação) para aumentar o número de genes piramidados. Para a SAM, foram utilizados marcadores SSR informativos em cada cruzamento. Marcadores SSR foram considerados informativos quando o alelo de resistência da fonte contendo o gene alvo poderia ser seguido na progênie, mesmo em cruzamentos entre híbridos, ambos contendo o mesmo alelo. Foram utilizados marcadores publicados em estudos de mapeamento genético para a FAS e o mapa consenso da soja. Foram obtidas plantas contendo genes piramidados, de 2 a 4 genes por planta. Essas plantas podem ser usadas como fonte de resistência múltipla em programas de melhoramento para obter variedades de soja com resistência mais durável à FAS.

ABSTRACT. The present study aimed at pyramiding ASR-resistance genes through microsatellite (SSR) marker-assisted selection (MAS) and demonstrating the pyramiding steps. To obtain the first generation of gene pyramiding, crosses were made between introduced plants (PI’s), which have the genes Rpp1, Rpp2, Rpp3, Rpp4, and Rpp5. F1 plants from the initial crosses were intercrossed to obtain plants with the four resistance genes (second pyramiding generation). Plants selected from this second generation were again intercrossed (third pyramiding generation) to increase the number of pyramided genes. For MAS, we used informative SSR markers in each cross. SSR markers were considered informative when the source resistance allele containing the target gene could be followed in the progeny, even in crosses between hybrids that both contained the same allele. Markers published in the ASR genetic mapping studies and in the consensus map of the soybean were used. We obtained plants containing from 2 to 4 genes pyramided per plant. These plants can be used as a source of multiple resistance in breeding programmes for obtaining soybean varieties with more durable resistance to ASR.

RESUMO Objetivou-se desenvolver e validar a metodologia da concentração de dióxido de carbono na avaliação do vigor de sementes de Triticum aestivum L. com base na espectroscopia no infravermelho. O método proposto quantifica o conteúdo de CO2 através de um sistema de arraste e exaustão do gás liberado pelas sementes. Amostras de 50 sementes, de seis lotes da cultivar CD 123 foram incubadas sob temperaturas de 15, 25 e 40 oC. Quantificou-se o conteúdo de CO2 liberado após 1, 3, 6, 9, 12 e 24 h de incubação. Paralelamente, avaliou-se a porcentagem de plântulas normais emergidas em campo. Foram calculados os coeficientes de correlação simples entre os testes. Após a determinação das condições de leitura, avaliou-se a precisão e exatidão utilizando 15 lotes de sementes. Para a avaliação da atividade respiratória em sementes de Triticum aestivum recomenda-se que amostras sejam incubadas a 25 oC por um período mínimo de 12 h, o que possibilita classificar lotes em diferentes níveis de vigor e predizer o estabelecimento de plântulas em campo, sendo o método adequado para a mensuração de CO2, pois externa precisão entre medidas sucessivas e concordância ao método de referência.

ABSTRACT The objective of this study was to develop and validate the methodology of carbon dioxide concentration in the evaluation of vigor of Triticum aestivum L. seeds based on infrared spectroscopy. The proposed method quantifies CO2 content using a drag system and exhaustion to the gas released by the seeds. Samples of 50 seeds of six lots of cultivar CD 123 were incubated at temperatures of 15, 25 and 40 °C. The CO2 content released after 1, 3, 6, 9, 12 and 24 h of incubation were quantified. Additionally, the percentage of normal seedlings emerged in the field were evaluated. The simple correlation coefficients were evaluated among tests. After determining the reading conditions, the precision and accuracy of the proposed method were evaluated, using 15 lots of seeds. For the evaluation of the respiratory activity in Triticum aestivum seeds, a sample of 25 seeds, incubated at 25 °C for a minimum of 12 h is recommended since it allows to classify lots with different levels of vigor and predict the establishment of seedlings in the field, being the appropriate method for measuring CO2 as it externalizes precision between successive measurements and agreement with the reference method.

Resumo: O objetivo deste trabalho foi identificar marcadores de polimorfismos de nucleotídeo único (SNPs) ligados a locos controladores de características quantitativas (QTLs) associados a maiores conteúdos de proteína e óleo em soja. Foram avaliadas 169 cultivares brasileiras de soja, genotipadas com 6 mil marcadores SNPs. Os conteúdos de proteína e óleo foram obtidos pelo método de refletância no infravermelho próximo. As análises de correlação e regressão linear múltipla foram utilizadas para a identificação de desequilíbrio de ligação entre os marcadores SNPs e os QTLs associados às duas características. Foram identificados sete QTLs associados ao conteúdo de proteína, em seis cromossomos (2, 6, 11, 12, 13 e 16), o que explicou 60,9% da variação nesta característica. Para o conteúdo de óleo, foram identificados oito QTLs em seis cromossomos (1, 4, 5, 6, 17 e 19), o que explicou 78,3% da variação na característica. A correlação entre o número de locos com alelos favoráveis e as características avaliadas foi de 0,49 para o conteúdo de proteína e de 0,60 para o conteúdo de óleo. Os marcadores moleculares identificados estão mapeados em regiões genômicas que contêm QTLs previamente mapeados para as duas características, o que reforça a associação dessas regiões com o controle genético dos conteúdos de óleo e proteína em soja.

Abstract: The objective of this work was to identify single-nucleotide polymorphism (SNP) markers linked with quantitative trait loci (QTLs) associated with increased contents of protein and oil in soybean. A total of 169 Brazilian soybean varieties, genotyped with 6,000 SNP markers, were evaluated. Protein and oil contents were obtained with the near-infrared reflectance method. Correlation and multiple linear regression analyses were used to identify linkage disequilibrium between SNP markers and the QTLs associated with the two characteristics. Seven QTLs were found to be associated with protein content, on six chromosomes (2, 6, 11, 12, 13, and 16), explaining 60.9% of the variation in this trait. For oil content, eight QTLs were identified on six chromosomes (1, 4, 5, 6, 17, and 19), explaining 78.3% of the variation in the trait. The correlation between the number of loci containing favorable alleles and the evaluated characteristics was 0.49 for protein content and 0.60 for oil content. The molecular markers identified are mapped in genomic regions containing QTLs previously mapped for both characteristics, which reinforces the association between these regions and the genetic control of oil and protein contents in soybean.

Abstract CD 1104 is a cultivar indicated for the wheat-producing regions 1, 2, 3, 4 (irrigated) and 4 (rainfed) of the states of RS, SC, PR, SP, MS, MG, DF, GO, and MT. Its suitability for the industrial segment of strong flours and yield potential (mean of 4.427 kg ha-1) are high.

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.

Abstract CD 1805, indicated for the wheat growing in Regions 1, 2 and 3 in the states of Rio Grande do Sul, Santa Catarina and Paraná. The cultivar has quality standards for cookie production and high yield performance with a mean of 3899 kg ha-1, exceeding the controls by 4%.