Análise dialélica de linhagens de milho com ênfase na resistência a doenças foliares

Abstract

Resumo -O objetivo deste trabalho foi identificar o tipo de ação gênica predominante para resistência a Exserohilum turcicum, Phaeosphaeria maydis, Physopella zeae e Puccinia polysora, e determinar o potencial genético de linhagens endogâmicas de milho (Zea mays) para a obtenção de híbridos com elevado desempenho agronômico e resistência a doenças foliares. Os 41 híbridos F 1 , provenientes de cruzamentos dialélicos entre dez linhagens endogâmicas, e as testemunhas P3069, P30F90, BG7060, Balu761 e Dow2A120 foram avaliados em quatro locais, tendo-se utilizado o delineamento experimental de blocos ao acaso, com três repetições. Os híbridos LGS 3 xLGS 9 , LGS 2 xLGS 6 , LGS 2 xLGS 4 e LGS 2 xLGS 3 apresentaram excelente desempenho em comparação às testemunhas, quanto aos diferentes caracteres avaliados. As linhagens com maior frequência de alelos favoráveis foram LGS 2 , LGS 9 , LGS 4 e LGS 3 . Os efeitos gênicos aditivos são os mais importantes para a resistência a P. maydis e altura de espiga, enquanto os não aditivos são mais importantes para a produtividade, altura de planta, resistência à E. turcicum, P. zeae e P. polysora.Termos para indexação: Exserohilum turcicum, Phaeosphaeria maydis, Physopella zeae, Puccinia polysora, Zea mays, efeito genético. Diallel analysis of maize inbred lines with emphasis on resistance to leaf diseasesAbstract -The objective of this work was to identify the predominant type of gene action for resistance to Exserohilum turcicum, Phaeosphaeria maydis, Physopella zeae and Puccinia polysora, and to determine the genetic potential of maize (Zea mays) inbred lines in order to obtain hybrids with high agronomic performance and resistance to leaf diseases. Forty-one F 1 hybrids from the diallel crosses between ten endogamic lines, and the controls P3069, P30F90, BG7060, Balu761, and Dow2A120 were evaluated in four places, using a randomized block experimental design, with three replicates. The hybrids LGS 3 xLGS 9 , LGS 2 xLGS 6 , LGS 2 xLGS 4 and LGS 2 xLGS 3 showed an excellent performance in comparison with the controls, for the different characters evaluated. The lines with higher frequency of favorable alleles were LGS 2 , LGS 9 , LGS 4 and LGS 3 . The additive genetic effects are the most important for the resistance to P. maydis and for ear height, while nonadditive genetic effects are more important for yield, plant height, resistance to E. turcicum, P. zeae and P. polysora.

Análise dialélica de linhagens de milho quanto à responsividade ao fósforo e à sua eficiência de uso

“…Em geral, os efeitos gênicos não aditivos predominam quanto à produtividade (Hallauer & Miranda Filho, 1985;Nihei & Ferreira, 2012) e eficiência de utilização de P em milho (Fritsche-Neto et al, 2010;DoVale & Fritsche-Neto, 2013;Mendes et al, 2014). Contudo, alguns dialelos indicam a predominância de efeitos aditivos quanto à produtividade, resistência a doenças e capacidade de expansão do milho-pipoca (Freitas Júnior et al, 2006;Scapim et al, 2006a), resistência à mancha-branca (Nihei & Ferreira, 2012), e mesmo quanto à eficiência de uso de P (Meirelles, 2013).…”

“…Contudo, alguns dialelos indicam a predominância de efeitos aditivos quanto à produtividade, resistência a doenças e capacidade de expansão do milho-pipoca (Freitas Júnior et al, 2006;Scapim et al, 2006a), resistência à mancha-branca (Nihei & Ferreira, 2012), e mesmo quanto à eficiência de uso de P (Meirelles, 2013).…”

Association mapping and genetic control for northern leaf blight (Exserohilum turcicum) resistance in maize lines

“…Therefore, it is advisable to note that the maximum incidence and severity indexes in this study were about 0 to 75% in leaves of the upper middle third of the plant with lesions (grades ranged from 1 to 5), allowing a representative discrimination of the resistance levels. This amplitude of severity was equal to or greater than the studies of northern leaf blight under natural infestations (Viera et al, 2009;Nihei and Ferreira, 2012). Analyzing the averages of the parents (Table 2), it can be observed that the parental 1 and 2 were highly contrasting, since they presented totally divergent average values for the disease in question.…”

“…The maize crop in Brazil began to face serious disease problems from the 1990s, both by increasing frequencies and by severe qualitative and quantitative damages to production (Nihei and Ferreira, 2012). This increase in the amount of diseases is highly related to changes in the production system of maize crop, such as expansion of the agricultural border, expansion of planting seasons (crop and winter crop), adoption of direct planting, increased use of irrigation systems, lack of crop rotation and use of susceptible materials (Silva et al, 2015).…”

Research Article Genetic control and combining ability of agronomic attributes and northern leaf blight-related attributes in popcorn.

“…Results concerning the prominence of gene effects on resistance to E. turcicum in conventional corn have been controversial. Paterniani et al (2000) and Vivek et al (2010), for instance, found that the additive genes were the most important in the expression of resistance to E. turcicum; the opposite occurred in the study developed by Nihei and Ferreira (2012). These findings indicate that genetic control for this trait may vary across the different sources of resistance.…”