Diallel analysis for frogeye leaf spot resistance in soybean

Abstract

-Seven soybean cultivars (Bossier, Cristalina, Davis, Kent, Lincoln, Paraná and Uberaba), with different levels of resistance to Cercospora sojina, were crossed in a diallel design to determine the general (GCA) and specific (SCA) combining abilities relative to the inheritance of the resistance. Race 04 of the fungus was inoculated in the parents and in the 21 F 1 hybrids in a greenhouse in a completely randomized design, with 12 replications. The reactions to the disease were evaluated 20 days after the inoculation, always on the most infected leaflet. Both GCA and SCA were significant for all the evaluated characters, being inferred that, for the expression of the characters, the additive, dominant and, possibly, epistatic genic actions were important. The largest values of estimated SCA effect ) ŝ ( ij were observed in the hybrid combinations where at least one parent presented high GCA. Cristalina, Davis and Uberaba cultivars showed the largest estimates for GCA effect ( i ĝ ), and from the analysis of ii Ŝ , the contribution of these parents to heterosis of their hybrids will be towards the reduction of the disease symptoms. Therefore, these cultivars are indicated as parents in breeding programs that seek the development of soybean cultivars with resistance to frogeye leaf spot.Index terms: Glycine max, Cercospora sojina, combining ability, heterosis, genetic resistance, genetic parameters. Análise dialélica da resistência à mancha olho-de-rã em sojaResumo -Sete cultivares de soja (Bossier, Cristalina, Davis, Kent, Lincoln, Paraná e Uberaba) com diferentes níveis de resistência à Cercospora sojina foram cruzadas de modo dialélico para avaliar as capacidades geral (CGC) e específica (CEC) de combinação quanto à herança da resistência. A raça 04 do fungo foi inoculada nos progenitores e nos híbridos F 1 , em casa de vegetação, num delineamento inteiramente casualizado, com 12 repetições. As avaliações da reação à doença foram feitas 20 dias após a inoculação, sempre no folíolo mais infectado. Ambas, CGC e CEC, foram significativas quanto a todos os caracteres avaliados, inferindo-se que, para a expressão dos caracteres, as ações gênicas aditivas, dominantes e, possivelmente, interações epistáticas foram importantes. Os maiores valores dos efeitos da CEC estimados ( ij ŝ ) foram observados nas combinações híbridas dos cruzamentos em que pelo menos um progenitor apresentou alta CGC. As cultivares Cristalina, Davis e Uberaba apresentaram as maiores estimativas do efeito de CGC ( i ĝ ) e, pela análise de ii Ŝ , a contribuição desses genitores para a heterose de seus híbridos será no sentido de redução dos sintomas da doença. Portanto, essas cultivares são indicadas como genitores em programas de melhoramento que visem à obtenção de cultivares de soja com resistência à mancha olho-de-rã.Termos para indexação: Glycine max, Cercospora sojina, capacidade combinatória, heterose, resistência genética, parâmetro genético.

Interference of genotypes x environments interaction in the genetic control of resistance to Asian rust soybean

“…There are other reports in the literature that corroborate these results according to which dominance was not important in soybean rust control Ribeiro et al, 2007). The superiority of GCA over SCA was also reported for other soybean diseases, such as frogeye spot, caused by the Cercospora sojina pathogen (Gravina et al, 2003). Cho & Scott (2000) observed similar result for other traits.…”

Gene Action and Combining Ability Analysis in some Soybean Quantitative Characters

“…The rest crosses gave insignificant or significant negative SCA effects in the same order. These findings were also found by Gravina et al (2003), , Solgotra et al (2009), Durai and Subbalakshmi (2010), Shiv et al (2011), NassarM.A.A. (2013 and Shehzad et al(2015).…”

“…It could be concluded that these Crosses would be efficient and prospective in breeding programs for improving seed yield per plant. Significant positive heterotic effects relative to higher yielding parent were also reached before by Pandini et al (2002), Gravina et al (2003), Ramana and Satyanarayana,(2006 b), Yang andGai (2009), Sudaric et al (2009), Yin, and Yi, (2009) and Nassar (2013).…”

“…Ranged from (1.76 to 6.73), significant positive heterotic effects were reached before by Habeeb et al (1988 a), Refat (1998), El-Hosary et al (2001). Pandini et al (2002), Gravina et al (2003), , Durai and Subbalakshmi (2010), and assar MAA (2013).…”

Analysis of combining ability in soybean cultivars

“…The methodology of analysis proposed by Griffing (1956) was used in soybean by Leffel and Weiss (1958), Singh et al (1974), Kaw and Menon (1981), Toledo and Kiihl (1982 b), Cruz et al (1987), Gravina et al(2003), among others. The GCA and SCA of cultivars were evaluated in relation to different traits, such as: "days to flowering", "days to maturation", "number of nodes", "number of branches", "plant height" and "heritability of disease resistance ".…”