RESUMEN La selección de poblaciones segregantes con potencial para derivar líneas es esencial para los programas de mejoramiento. El presente trabajo presenta el potencial de las poblaciones tropicales de trigo F2 (Triticum aestivum L.) generadas a partir de combinaciones de cruces dialélicos completos. Para ello, se combinaron ocho cultivares de trigo tropical en un diseño dialélico completo en 2019 después de multiplicar semillas Fj en invernadero y se evaluaron en campo las semillas de 56 poblaciones F2, más los ocho progenitores, en la cosecha de invierno de 2020 en un diseño reticular simple (8x8) en Vicosa, MG, Brasil. Se evaluaron las variables: severidad de la mancha amarilla (Pyrenophora triticirepentis), severidad del tizón (WHB) (Magnaporthe oryzae pathotype Triticum), número de días hasta embuchamiento, altura de la espiga y peso total de grano en la parcela. El análisis dialélico se realizó utilizando modelos mixtos para obtener los efectos de capacidad combinatoria general (GCA), capacidad combinatoria específica (SCA) y estimación de valores genotípicos de la población. El efecto aditivo predominó para el control de todas las variables, excepto para la altura de la espiga. Hubo mayores efectos de GCA para el conjunto de plantas madres progenitoras. La he-redabilidad, en sentido estricto, osciló entre 0.20 (tizón) y 0.66 (embuchamiento). Hubo efecto de la CGA materna para todas las variables, mientras que para la CGA paterna solo para número de días hasta embuchamiento y peso total de grano en la parcela. Las poblaciones derivadas de los cultivares TBIO Aton, TBIO Ponteiro y TBIO Sossego presentaron menor severidad de la enfermedad, mientras que las combinaciones de BRS 254, BRS 264 y BRS 394 presentaron un tiempo de maduración más temprano. Las combinaciones más promisorias para derivar líneas para el conjunto de variables evaluadas fueron BRS 254 x CD 1303, BRS 394 x TBIO Aton, TBIO Aton x BRS 254, CD 1303 x BRS 254 y CD 1303 x BRS 264.

ABSTRACT The selection of segregating populations with the potential for derived lines is essential for breeding programs. The present work analyzes the potential of tropical F2 wheat (Triticum aestivum L.) populations originated from complete diallel cross combinations. For this purpose, eight tropical wheat cultivars were combined in a complete diallel design in 2019 after Fj seeds were multiplied in a greenhouse and the seeds of 56 F2 populations, plus the eight parents, were evaluated in the field in Vicosa, MG, Brazil in the winter harvest of 2020 using a simple lattice design (8x8). The trait scores of (1) severity of tan spot (Pyrenophora triticirepentis), (2) severity of wheat head blast (WHB) (Magnaporthe oryzae pathotype Triticum), (3) days to heading, (4) spike height, (5) and total grain weight of the plot were evaluated. We performed a diallel analysis using mixed models to obtain the effects of general combining ability (GCA), specific combining ability (SCA), and estimation of population genotypic values. The additive effect predominated for the control of all traits, except for spike height. There were greater GCA effects for the set of parental maternal plants. Heritability, in the narrow sense, ranged from 0.20 (blast) to 0.66 (heading). There was an effect of maternal GCA for all variables, while for paternal GCA the effect was only for days passed for head and total grain weight. Populations derived from the cultivars TBIO Aton, TBIO Ponteiro, and TBIO Sossego had lower disease severity, while the combinations from BRS 254, BRS 264, and BRS 394 had earlier maturation time. The most promising combinations to derive lines for the set of traits were BRS 254 x CD 1303, BRS 394 x TBIO Aton, TBIO Aton x BRS 254, CD 1303 x BRS 254, and CD 1303 x BRS 264.

ABSTRACT. The selection of superior genotypes of soybean entails a simultaneous evaluation of a number of favorable traits that provide a comparatively superior yield. Disregarding the population effect in the statistical model may compromise the estimate of variance components and the prediction of genetic values. The present study was undertaken to investigate the importance of including population effect in the statistical model and to determine the effectiveness of the index based on factor analysis and ideotype design via best linear unbiased prediction (FAI-BLUP) in the selection of erect, early, and high-yielding soybean progenies. To attain these objectives, 204 soybean progenies originating from three populations were examined for various traits of agronomic interest. The inclusion of the population effect in the statistical model was relevant in the genetic evaluation of soybean progenies. To quantify the effectiveness of the FAI-BLUP index, genetic gains were predicted and compared with those obtained by the Smith-Hazel and Additive Genetic indices. The FAI-BLUP index was effective in the selection of progenies with balanced, desirable genetic gains for all traits simultaneously. Therefore, the FAI-BLUP index is an adequate tool for the simultaneous selection of important traits in soybean breeding.

ABSTRACT: Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.

Abstract The improvement of superior wheat cultivars depends on the identification of promising segregating populations to derive superior lines. A lattice model (8×8) involving 56 F2 populations and eight parents was conducted in the 2020 cropping season, and grain yield per plant was evaluated for every F2 population, with further analysis of the population potential by Jinks and Pooni method via REML/BLUP. A total of 5,410 F2 plants were evaluated in this study. The results showed that the use of genetic variance associated with the individual genotypic value (BLUP) was superior compared with the use of variance and traditional phenotypic values. The F2 populations, CD 1303/BRS 254, CD 1303/Tbio Duque, CD 1303/Tbio Ponteiro, BRS 264/Tbio Aton, Tbio Ponteiro/Tbio Aton, and Tbio Sossego/CD 1303 had the highest likelihood of deriving superior lines.

ABSTRACT: The study of adaptability and stability underlies the cultivar recommendation process for all crops. There is a considerable number of statistical methods available for this purpose, but little is known about their actual adoption by the Brazilian scientific community. The objective of this study was to carry out a systematic review of the scientific literature on the adaptability and stability methods used in maize and soybean in Brazil from scientific articles published between 1970 and 2017 in Brazilian journals. Article searches were carried out in journals indexed through the SciELO database. The articles were classified according to the year of publication and the adaptability and stability methods used. We also evaluated the pattern of association between methods. We found 113 articles on adaptability and stability in maize and soybean, in which 21 methods were listed. The most commonly used method was the Eberhart and Russell methodology. The Cruz, Torres, and Vencovsky along with the AMMI methods were also widely used. The number of articles using most methods decreased in the current decade, except for the GGE Biplot, MHPRVG, and Centroid methods. In studies with more than one method, the methods were more likely to be used together with the Eberhart and Russell methodology. Adaptability and stability in maize and soybean have been widely studied over the last several decades in Brazil, although the number of publications on this subject has decreased over this time period.

Abstract Parent selection is a crucial step in breeding programs. In the present study, we evaluated the genetic diversity in tropical wheat genotypes using best linear unbiased predictions (BLUPs) by different grouping methods. We identified potential parents to compose a crossing block with the aim of improving wheat for the Brazilian Cerrado. A total of 41 tropical wheat genotypes were evaluated in a field experiment. The evaluated traits included days to flowering; disease symptoms of fusarium head blight, blast, and leaf rust; flag leaf height; plant height; spike mass; hectoliter weight; and grain yield. The BLUPs were predicted and, from these, the standardized average Euclidean distance was calculated. Then, UPGMA, Tocher, and principal component clusters were generated from this genotypic distance matrix. Evaluating genetic diversity based on BLUP allowed the identification of two groups of highly dissimilar genotypes with high estimated genotypic values with which to compose a partial diallel.

RESUMO Sacha inchi (Plukenetia volubilis) é nativa da região amazônica e suas sementes tem um alto teor de ácidos graxos mono e poliinsaturados, tornando-a interessante para a indústria farmacêutica e cosmética. O objetivo deste estudo foi analisar a diversidade genética de sacha inchi e caracterizar os acessos com base em características fenotípicas. Foi realizada coleta e biometria de frutos e sementes de 25 acessos do banco de germoplasma de sacha inchi da Embrapa Amazônia Ocidental em Manaus-AM. Os dados foram submetidos a análise de variância, distância de Mahalanobis, correlação canônica e diversidade genética por análise de variância molecular (AMOVA). Houve diferenças significativas entre as médias das variáveis analisadas, contudo, não houve correlação canônica significativa para os grupos de variáveis. De acordo com AMOVA, aproximadamente 60% da variação observada esteve dentro de acessos. Os resultados mostram variabilidade entre acessos, sendo importante explorar a variação intra-acessos para obter melhores resultados em programas de melhoramento.

ABSTRACT Sacha inchi (Plukenetia volubilis) is native to the Amazon region and has a high seed content of mono and polyunsaturated fatty acids, making it interesting for the pharmaceutical and cosmetic industry. The purpose of this study was to analyze sacha inchi genetic diversity and describe accessions based on phenotypic characteristics. Fruits and seeds of 25 accessions from the sacha inchi genebank of Embrapa Amazônia Ocidental in Manaus, Amazonas state, were sampled and biometrically measured. The data were subjected to analysis of variance, Mahalanobis distance, canonical correlation, and genetic diversity among and within accessions by analysis of molecular variance (AMOVA). There were significant differences among the means of the analyzed traits, but no significant canonical correlation for the groups of traits. According to AMOVA, approximately 60% of the observed variation was within accessions. The results showed variability among accessions, and that the variation within accessions should be explored to obtain best results in breeding programs.

RESUMO. A coleta de palmito via extrativismo vem reduzindo as reservas naturais de açaí e juçara, sendo o palmito de pupunha uma excelente opção para obtenção de palmito plantado, pois além de diminuir a pressão da exploração extrativista sobre essas duas espécies, possui alto grau de perfilhamento e não apresenta oxidação pós-colheita. Foram testadas 72 progênies de pupunheira, em cinco anos, no campo experimental da Embrapa Amazônia Ocidental, em delineamento blocos casualizados com 36 repetições e uma planta por parcela. Os parâmetros genéticos foram estimados através de modelos mistos (REML/BLUP), foram também realizadas análises de repetibilidade, seleção de progênies, seleção de indivíduos por meio de BLUP individual, índice de seleção Mulamba-Rank e agrupamento de otimização de Tocher. As análises realizadas revelaram a existência de variabilidade genética, baixa repetibilidade, variando de 0,3307 até 0,6698 para cinco anos e herdabilidades variando de 51% a 23% para seleção de progênies nas variáveis analisadas, o agrupamento revelou dois grupos distintos. A seleção de progênies deve ser a principal estratégia de seleção e cruzamentos entre progênies superiores de grupos diferentes devem ser enfatizados.

ABSTRACT. Heart of palm harvesting and exploitation has reduced the natural reserves of açaí and juçara; hence, the peach palm is an excellent option as source of heart of palm that can reduce the pressure on these two species. The peach palm has high tillering and no post-harvest oxidation. An experiment in a randomized block design with 72 progenies of peach palm, 36 replications and a single tree plot was performed for five years at the experimental field of Embrapa in the Western Amazon. Genetic parameters were estimated using two mixed models, one based on progeny means and the second on joint information from crops. A repeatability analysis, genotype selection, and progeny selection were performed; the Mulamba and Mock selection index was determined; and Tocher’s clustering method was applied. The repeatability analysis revealed the existence of genetic variability, low repeatability, which ranged from 0.3307 to 0.6698 for five years. The analysis performed through the progeny means showed a heritability that varied from 51% to 23% for in all variables; the clustering revealed two groups. The progeny selection should be the main selection strategy, and crosses of superior progenies of different groups should be emphasized.

Abstract The efficiency of maize transformation mediated by Agrobacterium tumefaciens is influenced by various factors. The aim of this study was to test the effect of different concentrations of N6 salts (50% - half strength, and 100% - full strength) in the infection and cocultivation media on genetic transformation efficiency of the L3 tropical elite maize line. Immature embryos were transformed via A. tumefaciens harboring the binary vector pTF102 containing the genes uidA and BAR under control of the CaMV35S promoter. The efficiency of the transgenic events produced was 3% for full strength and 1.1% for half strength N6 salts. Although under a lower concentration of salts, GUS expression was stronger; under this concentration, regeneration was less efficient. Thus, the results showed that the presence of 100% N6 salts in the infection and cocultivation media favored genetic transformation of the L3 maize inbred line mediated by A. tumefaciens.

RESUMO. Este trabalho objetivou a construção de um mapa genético e identificação de locos de características quantitativas (QTLs) que controlam características do sistema radicular do arroz. Foi avaliada uma população F2:3 composta de 150 famílias a partir do cruzamento entre as variedades IAC 165 x BRS Primavera. A genotipagem foi realizada na população F2 utilizando 3.742 marcadores SNP (Polimorfismo de um Único Nucleótido). A avaliação do sistema radicular nas populações F3 foi realizada através de fenotipagem em larga escala baseada na geração de imagem com scanner raiz CI-600 e na quantificação através do software WinRhizo(r). Foi realizado experimento em delineando blocos casualizados, em casa de vegetação com três repetições. Foram consideradas as variáveis comprimento, área de contato da raiz e volume nas profundidades de 5 a 25 cm e 25 a 45 cm. A análise dos marcadores SNP permitiu a construção de um mapa genético com comprimento total de 1424 cM. O grupo de ligação com maior área de cobertura foi o número 3 com 270 cM (100 SNPs), seguido pelo grupo de ligação 1, com 249 cM (170 SNP), e 2 com 163 cM (99 SNP). A análise genética permitiu a detecção de QTL para todas as características estudadas.

ABSTRACT. The aim of this work is the construction of a genetic map and identification of quantitative trait loci (QTLs) that control characteristics of the root system of rice. We evaluated a F2:3 population composed of 150 families from the cross between the varieties IAC 165 × BRS Primavera. Genotyping was performed in the F2 population using 3,742 SNP (Single Nucleotide Polymorphism) markers. The evaluation of the root system in the F3 population was performed through a large-scale phenotyping method based on image generation with a CI-600 root scanner and on quantification through the WinRhizo(r) software. The experiment was arranged in a randomized block design with three replications performed under greenhouse. The variables analyzed were root length, root surface area and root volume at the depths of 5 to 25 cm and 25 to 45 cm. The SNP markers analysis allowed the construction of the genetic map with a full length of 1424 cM. The linkage group with the largest coverage area was number 3 with 270 cM (100 SNPs), followed by linkage group 1 with 249 cM (170 SNPs) and linkage group 2 with 163 cM (99 SNPs). The genetic analysis allowed the detection of QTLs for all the characteristics.

AbstractMaize is considered a source of carotenoids; however, these compounds are highly unstable, degraded by high temperatures, exposure to light and presence of oxygen. The objective of this work was to evaluate the influence of the moisture and type of drying applied to grains on the level of carotenoids in yellow maize. The experiment was conducted in a completely randomized design (2 × 4 factorial), two levels of initial moisture at the harvest (22 and 19%) and three types of drying (in the sun; in the shade and in a dryer) and control (no drying). The samples of grains after drying with 12% of final moisture were analyzed by concentration of total carotenoids, carotenes (α-carotene + β-carotene), monohydroxilated carotenoids (β-cryptoxanthin), and xanthophylls (lutein + zeaxanthin). Initial moisture, type of drying and the interaction between moisture versus drying influence (p≤0.05) the levels of carotenoids in grains. This is the first report about the drying conditions and harvest’s initial moisture as influence on the profile and content of carotenoids in maize grains. Based on the results, this work suggested that the harvest be carried out preferably when the grains present 22% humidity, with drying in a dryer or in shade for further use or storage.

O estresse por deficiência hídrica pode acarretar sérios danos à cultura do arroz de terras altas, principalmente na redução da produtividade. Por isto, a seleção de genótipos mais adaptados a esta condição faz-se necessária. Este trabalho avaliou as características agronômicas e temperatura foliar, em linhagens F7 de arroz de terras altas submetidas a duas condições de irrigação (com e sem estresse de deficiência hídrica), no sentido de possibilitar a seleção de materiais mais tolerantes a este estresse abiótico. Em 142 linhagens endogâmicas e seus dois genitores, Bico Ganga Curto e Chorinho, foram avaliados a temperatura foliar (ºC), dias até o florescimento, número de perfilhos e de panículas por metro linear, esterilidade das espiguetas (%), altura da planta (cm), massa de mil espiguetas (g) e produtividade (kg ha-1). O delineamento experimental utilizado foi o látice triplo 12x12, com e sem estresse de deficiência hídrica. Foram selecionadas 15 linhagens, por meio do Índice de Susceptibilidade à Seca, as quais foram comparadas com seus genitores, pelo teste Tukey. Verificou-se que houve aumento no número de dias para o florescimento e para a esterilidade das espiguetas, em condições de deficiência hídrica. Nesta mesma condição, houve redução na altura da planta e número de perfilhos e de panículas por metro linear. Dentre as linhagens, destacou-se a 51, que apresentou boa produtividade, em ambas as condições de cultivo.

Water deficiency stress can seriously damage the upland rice crop, mainly reducing its yield. Therefore, the selection of genotypes better adapted to drought is relevant. This study aimed at evaluating agronomic traits and leaf temperature, in F7 upland rice lines under two irrigation conditions (with and without water deficit stress), in order to allow the selection of lines more tolerant to this abiotic stress. In 142 recombinant inbred lines and their two parents, Bico Ganga Curto and Chorinho, the leaf temperature (ºC), days to flowering, number of tillers and panicles per linear meter, spikelet sterility (%), plant height (cm), one thousand spikelets weight (g) and yield (kg ha-1) were evaluated. The experimental design used was a 12x12 triple lattice, with or without water stress. Fifteen lines were selected by using the Drought Susceptibility Index and compared with their parents by the Tukey test. An increase was observed in the number of days to flowering and spikelet sterility, under water deficit stress. Under the same condition, there was a reduction for plant height and number of tillers and panicles per linear meter. Among all lines, the 51 distinguished itself by presenting a high yield, concerning both environments.

Ainda que sejam considerados os aspectos de magnitude e significância, o estudo de correlações entre caracteres por si só não garante causa e efeito entre eles. Dessa forma, o objetivo deste trabalho foi desdobrar as correlações fenotípicas em seus efeitos diretos e indiretos, pela análise de trilha, considerando o perfil de carotenoides em genótipos de milho. Foram utilizados dados obtidos do ensaio nacional de cultivares de milho conduzido pela Embrapa Milho e Sorgo, no ano agrícola 2004/2005, com média de 10 genótipos em cinco ambientes. Avaliaram-se os teores de carotenoides totais (CT), α e β-carotenos, luteína, zeaxantina e β-criptoxantina. A xantofila zeaxantina apresenta o maior efeito direto sobre β-caroteno. As altas correlações entre β-caroteno e carotenoides totais e entre β-caroteno e β-criptoxantina são devidas ao efeito indireto, via zeaxantina. A seleção direta de genótipos com altos teores de β-caroteno apresenta-se como a alternativa de maior efetividade, mas se outras frações de carotenoides também forem consideradas, esquemas de seleção simultânea de caracteres, por meio da utilização de índices de seleção, mostram-se mais eficientes na obtenção de genótipos com altos teores de β-caroteno do que a resposta correlacionada.

Although aspects of magnitude and significance are considered, the study of correlations between traits, alone, does not necessarily guarantee a cause and effect relationship between them. Therefore, the objective of this study was to use path analysis to allow the unfolding of correlations in direct and indirect effects, considering the carotenoids profile of maize genotypes. Data was obtained from the national assay of maize cultivars conducted by Embrapa Maize and Sorghum in the 2004/2005 growing season, with means of ten genotypes in five environments. The contents of total carotenoids (CT), alpha and β-carotene, lutein, zeaxanthin and β-criptoxantin were evaluated. Xanthophyll zeaxanthin provided the highest direct effect on β-carotene. The high correlations between β-carotene and total carotenoids and between β-carotene and β-criptoxanthin are due the indirect effect via zeaxanthin. The direct selection of genotypes with high levels of β-carotene appears as a more effective alternative, but if other fractions of carotenoids were also considered, methods of simultaneous selection of characters using selection indices are more efficient in obtaining genotypes with high levels of β-carotene than the correlated response.

Práticas efetivas são necessárias para o controle da ferrugem. O principal método de controle utilizado é a aplicação de fungicidas, o que aumentará substancialmente o custo de produção e são prejudiciais ao meio ambiente. A prevenção ainda é a melhor maneira de evitar mais perdas significativas na produção de soja. Alternativas, como o plantio de variedades resistentes ao fungo, também são importantes. O uso de variedades resistentes ou tolerantes é o método mais promissor para o controle da ferrugem asiática da soja. Recentemente, cinco genes de resistência a ferrugem da soja foram descritos Rpp1, Rpp2, Rpp3, Rpp4 e Rpp5. No entanto, pouco se sabe sobre a interação molecular entre a planta e ferrugem da soja e as rotas desencadeadas na planta pelo reconhecimento do patógeno. Compreender os mecanismos moleculares envolvidos nas respostas de defesa é de primordial importância no planejamento de estratégias para controle do estresse e, consequentemente, para aumentar a adaptação das plantas a condições limitantes.

Effective management practices are essential for controlling rust outbreaks. The main control method used is the application of fungicides, which increases substantially the cost of production and is harmful to the environment. Prevention is still the best way to avoid more significant losses in soybean yields. Alternatives, such as planting resistant varieties to the fungus, are also important. The use of resistant or tolerant varieties is the most promising method for controlling Asian soybean rust. Recently, five dominant genes resistant to soybean rust were described: Rpp1, Rpp2, Rpp3, Rpp4 and Rpp5. However, little is known about the molecular interaction among soybean plant and soybean rust and on the molecular pathway triggered by pathogen recognition. Understanding the molecular mechanisms involved in defense responses is of primary importance for planning strategies to control stress and, consequently, to increase plant adaptation to limiting conditions.

O objetivo deste trabalho foi determinar o fluxo gênico recíproco entre duas cultivares de soja, uma tolerante e outra sensível ao glifosato, além de aplicar estimadores para determinar a taxa de fecundação cruzada na população e o número de sementes híbridas na progênie. O experimento compôs-se de quatro blocos com 40 fileiras de soja, com 20 fileiras de cada cultivar (CD217 e CD219RR). No estádio R8, cinco fileiras, distantes 0, 5, 1, 2, 4 e 8 m da cultivar adjacente, foram colhidas, trilhadas e analisadas quanto à ocorrência de fluxo gênico. Como características marcadoras, foram utilizadas as cores da flor, hipocótilo e pubescência, e a tolerância ao glifosato. As cultivares contrastam quanto às características analisadas, cada uma condicionada por um gene com dois alelos, em interação de dominância completa. Na progênie da cultivar tolerante, a maior taxa de híbridos encontrada foi 0, 27% e, na progênie da cultivar sensível, identificou-se 0, 83%; pela hipótese do efeito diluição, as taxas de hibridação natural populacional seriam 0, 104 e 0, 388%, respectivamente. O fluxo gênico recíproco entre as cultivares CD217 e CD219RR não é o mesmo em ambas as direções. Os estimadores propostos são úteis para determinar a taxa de híbridos em amostras de sementes.

The objective of this work was to determine the reciprocal gene flow between two soybean cultivars, one tolerant and the other sensitive to glyphosate, as well as to use estimators to determine the outcrossing rate in the population and the number of hybrid seeds in the progeny. The experiment was composed of four blocks of 40 soybean rows, of which 20 rows of each cultivar (CD217 and CD219RR). At the R8 stage, five rows, distant 0.5, 1, 2, 4 and 8 m from the adjacent cultivar, were harvested, threshed and analyzed as for the occurrence of gene flow. As phenotypical markers, the trait color of flowers, hypocotil and pubescence, as well as the tolerance to glyphosate were used. The cultivars contrast for all the analyzed traits, each one conditioned by a single gene with two alleles, in a complete dominance interaction. In the tolerant cultivar progeny, the largest outcross rate was 0.27%, and in the sensitive cultivar progeny, 0.83% was identified; by the dilution effect hypothesis, the outcross rates in natural populations would be 0.104 and 0.388%, respectively. The reciprocal gene flow between CD217 and CD219RR cultivars is not the same in both directions. The proposed estimators are useful for determining the hybrid rates in seed samples.