Diversidade genética em cultivares e linhagens de feijão comum (Phaseolus vulgaris L.) utilizando análises multivariadas

O objetivo deste trabalho foi avaliar a divergência genética entre cultivares/ linhagens de feijão comum e indicar genitores contratantes e superiores para produzir populações segregantes com alta variabilidade. Avaliou-se 25 cultivares/linhagens de feijão, em delineamento de blocos ao acaso com três repetições. Os caracteres agronômicos avaliados foram: Número de dias para o florescimento, Ciclo, Altura média final das plantas, Altura média da inserção primeira vagem, Comprimento médio longitudinal das vagens, Número médio de vagens por planta, Número médio de sementes por vagem, Número médio de sementes por planta, Peso médio de 100 sementes e Produtividade de grãos. Os dados obtidos foram submetidos à análise de variância, seguido do teste de agrupamento de Scott e Knott. Para a análise da divergência genética entre as cultivares/linhagens foi empregada análise multivariada com base na distância generalizada de Mahalanobis, realizando posteriormente os métodos aglomerativos de otimização de Tocher, método hierárquico “UPGMA” e projeção de distância no plano 2D. O grau de preservação das distâncias genéticas no dendrograma foi verificado a partir do Coeficiente de Correlação Cofenética. Utilizou-se, também, o critério de Singh (1981) para quantificar a contribuição relativa das características para a divergência genética. As cultivares/linhagens avaliadas apresentam dissimilaridade genética quanto às características agronômicas avaliadas. A característica comprimento médio longitudinal das vagens é a que mais contribuiu para estimar a diversidade genética entre as cultivares/linhagens. E híbridos com maior efeito heterótico podem ser obtidos dos cruzamentos entre Iraí × Goiano Precoce, Iraí × Pérola, Goiano Precoce × CNFC 10467 e IAPAR 81 × Pérola

Genetics and mapping of a new anthracnose resistance locus in Andean common bean Paloma

Background: The Andean cultivar Paloma is resistant to Mesoamerican and Andean races of Colletotrichum lindemuthianum, the fungal pathogen that causes the destructive anthracnose disease in common bean. Remarkably, Paloma is resistant to Mesoamerican races 2047 and 3481, which are among the most virulent races of the anthracnose pathogen. Most genes conferring anthracnose resistance in common bean are overcome by these races. The genetic mapping and the relationship between the resistant Co-Pa gene of Paloma and previously characterized anthracnose resistance genes can be a great contribution for breeding programs. Results: The inheritance of resistance studies for Paloma was performed in F2 population from the cross Paloma (resistant) × Cornell 49–242 (susceptible) inoculated with race 2047, and in F2 and F2:3 generations from the cross Paloma (resistant) × PI 207262 (susceptible) inoculated with race 3481. The results of these studies demonstrated that a single dominant gene confers the resistance in Paloma. Allelism tests performed with multiple races of C. lindemuthianum showed that the resistance gene in Paloma, provisionally named Co-Pa, is independent from the anthracnose resistance genes Co-1, Co-2, Co-3, Co-4, Co-5, Co-6, Co-12, Co-13, Co-14, Co-15 and Co-16. Bulk segregant analysis using the SNP chip BARCBean6K_3 positioned the approximate location of Co-Pa in the lower arm of chromosome Pv01. Further mapping analysis located the Co-Pa gene at a 390 kb region of Pv01 flanked by SNP markers SS82 and SS83 at a distance of 1.3 and 2.1 cM, respectively. Conclusions: The results presented here showed that Paloma cultivar has a new dominant gene conferring resistance to anthracnose, which is independent from those genes previously described. The linkage between the Co-Pa gene and the SS82 and SS83 SNP markers will be extremely important for marker-assisted introgression of the gene into elite cultivars in order to enhance resistance.EEA SaltaFil: Castro, Sandra Aparecida de Lima. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Gonçalves-Vidigal, Maria Celeste. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Gilio, Thiago Alexandre Santana. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Lacanallo, Giselly Figueiredo. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Valentini, Giseli. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Martins, Vanusa da Silva Ramos. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Qijian, Song. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados UnidosFil: Galvan, Marta Zulema. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Hurtado-Gonzales, Oscar P. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados UnidosFil: Pastor-Corrales, Marcial Antonio. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados Unido

Taxa de pegamento de frutos em cruzamentos intraespecíficos de capsicum frutescens / Fruit set rate in intraspecific crossings of capsicum frutescens

O gênero Capsicum spp. compreende um grupo diversificado de pimentas e pimentões, o que permite seu uso em programas de melhoramento genético. Ainda que este mercado tenha crescido gradativamente, existem vários problemas fitossanitários que vêm provocando perdas significativas à cultura, estando entre eles à antracnose. Estudos visando à obtenção de híbridos resistentes a antracnose e com alta produtividade são necessários para suprir a demanda de mercado. Sendo assim, o objetivo do trabalho foi realizar cruzamentos intraespecíficos entre Capsicum frutescens e analisar a taxa de pegamento de frutos híbridos F1. O experimento foi realizado em telado protegido no campo experimental do laboratório de Melhoramento de Plantas localizado na Universidade do Estado de Mato Grosso, Campus de Cáceres. Para a obtenção dos híbridos intraespecíficos, foram utilizados acessos de C. frutescens do Banco Ativo de Germoplasma da UNEMAT, a escolha dos genitores utilizados foi em função de suas características do ponto de vista agronômico como elevado teor de antioxidantes e em distintas combinações. O pólen dos genitores masculinos foi coletado com antecedência e armazenados em cápsulas. O processo de hibridação foi diário durante os meses de janeiro e junho 2017, onde foi realizada a emasculação das flores dos genitores femininos, polinização manual e etiquetagem. Em janeiro foram realizadas   48 hibridações, contudo o tratamento 1 não apresentou botão floral, permanecendo sem cruzamento nesse período. Em relação aos demais tratamentos, obteve-se um sucesso de 100% de pegamento, exceto no tratamento 2 onde a taxa de pegamento foi de apenas 71,42%. Enquanto que no mês de junho foram realizadas 25 hibridações, sendo os tratamentos 3, 5, 7 e 9 nulos em função da ausência de botão floral. Para os tratamentos 1, 2, 4, 6 e 8 obteve-se sucesso na hibridação com taxa de pegamento de 33,33%, 75%, 50% e 83,33%, respectivamente.  A taxa de pegamento geral das hibridizações foi de 80,81%, sendo que, o mês de janeiro possibilitou a maior porcentagem de pegamento. 

Two hundred years since the birth of Mendel: who he was and where we have come from his works

During the 19th and 20th centuries, researchers in various parts of the world sought a theory that could explain the inheritance of traits in different organisms. One of them was Gregor Johann Mendel, born on July 20, 1822, in rural areas in a small village in the Silesian region, located then in the Austrian empire; today, the Czech Republic. However, Mendel celebrated his birthday on July 22 (Moreira, 2017). [...

GENETIC DIVERGENCE AMONG COTTON GENOTYPES GROWN IN THE MAIN SEASON AND OFF SEASON

The objective of this work was to evaluate the agronomic performance and estimate the genetic divergence of 18 cotton genotypes grown in the main season (sowed in December, 2012) and off season (sowed in January, 2013), considering their agronomic characteristics and resistance to Ramularia leaf spot. A randomized block experimental design was used, with five replications. The characteristics evaluated were plant height, first branch height, position of first fruiting branch, height of first fruiting branch, length between nodes, number of nodes, average number of bolls per plant, average boll weight, area under the disease progress curve (AUDPC) related to the Ramularia leaf spot severity, weight of 100 - seed from the plant middle third, fiber percentage, average production per plant, yield and cotton fiber quality. The results were subjected to individual and joint analysis of variance and the genetic divergence was estimated according to multivariate procedures (Mahalanobis' generalized distance and Tocher's optimization method). The dissimilarity matrices were summed to estimate the genetic divergence, considering both growing periods. Genetic variability was found among the genotypes evaluated, in both the main season and off season. The characteristic that most contributed to the genetic divergence in the main season was the production per plant and, in the off season, was the fiber percentage. According to the results of the present work, the crosses between the genotypes BRS - 335 and FMT - 707; FM - 910 and FMT - 707; and IMA - 08 - 12427 and FMT - 707 are recommended

Molecular characterization of common bean accessions using microsatellite markers

ABSTRACT The common bean, a legume of significant economic importance, is renowned for its extensive genetic variability. It is crucial to comprehend genetic diversity, analyze population structure, and understand relationships among commercial classes of accessions to facilitate genetic improvement. This study aimed to molecularly characterize 143 common bean accessions by employing 25 SSR molecular markers. The objectives were to estimate genetic diversity, analyze genetic structure, and cluster populations using the UPGMA and PCoA methods. A total of 105 alleles were amplified using microsatellite loci, and the observed heterozygosity was lower than expected across all loci, indicating inbreeding within the populations. Among the loci, 22 were highly informative, demonstrating their effectiveness and polymorphism in detecting genetic diversity. The genetic variability within the population was found to be the highest, while variation between populations was the lowest. The analysis of population structure revealed the presence of three populations with a notable rate of gene introgression. The UPGMA analysis categorized the accessions into 15 groups, but they did not form distinct clusters based on their geographic regions or gene pool. The first two principal coordinates accounted for 13.95% of the total variation among the accessions. The SSR markers employed effectively detected genetic variability among the common bean accessions, revealing that their genetic diversity was not correlated with their geographic distribution in this study

Fine mapping of an anthracnose-resistance locus in Andean common bean cultivar Amendoim Cavalo.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is one of the world's most destructive diseases of common bean. The use of resistant cultivars is the most cost-effective strategy to manage this disease; however, durable resistance is difficult to achieve due to the vast virulence diversity of the anthracnose pathogen. Finding new genes with broad-spectrum resistance increases the prospect of designing an effective anthracnose-management strategy. Genetic analysis confirmed the presence of a single, dominant anthracnose-resistance locus in AC, which we provisionally named Co-AC. Bulk segregant analysis and genetic mapping of two F2 populations from the crosses AC × PI207262 and AC × G 2333 were used to determine the position of the Co-AC locus in a 631 Kbp genomic region flanked by the SNP markers SS56 and SS92 on the lower arm of chromosome Pv01. By genotyping 77 F3 plants from the AC × PI207262 cross using nine additional markers, we fine-mapped the Co-AC locus to a significantly smaller genomic region (9.4 Kbp) flanked by the SNP markers SS102 and SS165. This 9.4 Kbp region harbors three predicted genes based on the common bean reference genome, notably including the gene model Phvul.001G244300, which encodes Clathrin heavy chain 1, a protein that supports specific stomatal regulation functions and might play a role in plant defense signaling. Because the Co-AC resistance locus is linked in cis, it can be selected with great efficiency using molecular markers. These results will be very useful for breeding programs aimed at developing bean cultivars with anthracnose resistance using marker-assisted selection. This study revealed the broad-spectrum resistance of AC to C. lindemuthianum and the existence of the Co-AC anthracnose-resistance locus. Fine mapping positioned this locus in a small genomic region on the lower end of chromosome Pv01 that contained three candidate genes for the Co-AC locus

Genetic Mapping for Agronomic Traits in IAPAR 81/LP97-28 Population of Common Bean (Phaseolus vulgaris L.) under Drought Conditions

One of the significant challenges of common bean breeding is developing cultivars with high yields under drought conditions. The present study attempted to map quantitative trait loci (QTLs) and identify molecular markers that are linked to drought tolerance in the common bean. We evaluated 160 recombinant inbred lines (RILs), derived from the cross between the carioca cultivars IAPAR 81 (drought tolerant) and LP97-28 (susceptible to drought). In 2014 and 2015, two experiments were conducted (DS—drought stress, and NS—no drought stress). In the DS experiment, water suppression was performed at the flowering stages R5 to R6. The results of our experiments showed that drought conditions play an essential role in reducing most of the traits that were evaluated. RILs under drought conditions reduced the grain yield by 62.03% and 24% in 2014 and 2015, respectively. We identified 15 quantitative trait loci distributed on the chromosomes Pv01, Pv02, Pv03, Pv07, Pv08, Pv09, Pv10, and Pv11, related to grain yield, seed yield per day, 100-seed weight, number of pods per plant, plant height, number of days for flowering, and number of days to maturity. The characteristics of seed yield per day, 100-seed weight, and number of days to maturity showed that QTLs colocalized on Pv07. Identifying QTLs that are linked to drought tolerance in the RIL population IAPAR 81 × LP97-28 is of particular importance for common bean breeding programs seeking to improve carioca beans that are cultivated in regions with drought conditions, such as Brazil