<b>Genetic control of partial resistance to Asian soybean rust</b> doi: 10.4025/actasciagron.v36i1.16919

Abstract

ABSTRACT. The genetic control of rust resistance was studied using the Caiapônia x IAC-100 and Luziânia x Potenza crosses. The F 2 and F 3 generations were evaluated. Rust severity was quantified through visual assessment of the middle third of three leaflets per plant and performed by three different evaluators; the average score was calculated foreach individual plant. From these data, we estimated the mean and variance of the genetic components by employing the weighted least squares method. The estimated number of genes and broad-and narrow-sense heritabilities were also obtained. It was concluded that rust resistance is a characteristic controlled by 2 to 23 genes that are predominantly dominant. The estimate of narrow-sense heritability was greater than 70% for the Caiapônia x IAC-100 cross, and the wide-sense heritability was greater than 60% for the Luziânia x Potenza cross; thus, it is possible to successfully select resistant individuals in early generations.Keywords: Glycine max, Phakopsora pachyrhizi, dominance variance, heritability, race non-specific disease resistance.Controle genético da resistência parcial à ferrugem asiática da soja RESUMO. Estudos sobre o controle genético da resistência à ferrugem asiática foram a conduzidos a partir dos cruzamentos Caiapônia x IAC 100 e Luziânia x Potenza. Foram avaliadas as gerações F 2 e F 3 . A severidade da ferrugem asiática foi obtida pela estimativa visual de 3 folíolos do terço médio/planta. A partir desses dados foram estimados os componentes genéticos de média e de variância, empregando-se o método dos quadrados mínimos ponderados. Foram obtidas também a estimativa do número de genes e da herdabilidade no sentido amplo e restrito. Concluiu-se que o controle genético da resistência à Phakopsora pachyrhizi governado por 2 a 23 genes, com predominância dos efeitos dominantes no controle. A estimativa da herdabilidade no sentido restrito acima de 70% para o cruzamento Caiapônia x IAC 100 e amplo acima de 60% para o cruzamento Luziânia x Potenza, mostrou que há possibilidade de sucesso na seleção de indivíduos resistentes já nas gerações iniciais. Palavras-chave:Glycine max, Phakopsora pachyrhizi, variância de dominância, herdabilidade, resistência raça não-específica.

Integration between genetic and chemical control on the progress of Asian soybean rust and yield

“…In the field, Maphosa et al (16) verified that such variability, isolate (genotype) x year (season), had a great impact on the severity of ASR. Therefore, there may be a greater effect of the environment on the disease severity (17).…”

Research Article Line selection and correlation between traits of soybean genotypes under high naturally occurring stink bug infestation

“…Overall, those genotypes have shown a lower disease severity compared to other studies that have identified potential sources of genetic resistance to this disease (Ribeiro et al, 2009;Glasenappet al, 2015). Still, the soybean lines' resistance to soybean rust severity may vary over time and it is associated with the genotype, the type of resistance mechanism according to the environmental factors or physiological effects (Martins and Juliatti, 2014).…”

Soybean genotype analysis for cyst nematode resistance

“…This result supports the appearance of a high FI in susceptible genotypes in the experiment, as presented by the genotype 57 (F5:6 BRSGO Caiapônia x IAC100, PL 01 (N50, D05) Bulk F5 obtained with high FI (285.2) as well as other susceptible genotypes, indicating the genetic segregation in obtaining the initial population in the F2 generation. Genotype 46 also obtained partial resistance to soybean rust (Phakopsora pachyrhizi) on field, in generation F4:5, where it was evaluated the partial resistance of soybean genotypes to the fungus; among the genotypes, significant differences appeared in number of average pustules and severity at 12 days after inoculation (Martins and Juliatti, 2012). The variety Engopa 316 RR -Sel.…”