Correlação da heterose de híbridos de milho com divergência genética entre linhagens

Abstract

Resumo -O objetivo deste trabalho foi avaliar a produtividade de híbridos simples de milho obtidos de cruzamentos dialélicos entre linhagens divergentes, estimar a capacidade de combinação das linhagens e confirmar se a divergência genética entre as linhagens, obtida por marcadores moleculares, é correlacionada com a heterose dos híbridos simples no campo. Trinta e seis híbridos resultantes do dialelo parcial e as 12 linhagens parentais foram avaliadas em Campinas em blocos ao acaso, com três repetições e duas testemunhas. A capacidade de combinação das linhagens foi estimada de acordo com o modelo 4 de Griffing. Estimaram-se a correlação matricial, mediante a estatística de Mantel, entre heterose, produtividade e capacidade específica de combinação com divergência genética por AFLP e SSR. Destacou-se o híbrido PM518 x L111 e as linhagens PM518, IP4035 e L111 apresentaram efeitos positivos da capacidade geral de combinação. As estimativas de heterose variaram de 927 a 6.698 kg ha -1. Houve correlação entre heterose e divergência genética por AFLP e SSR. No entanto, a divergência genética não foi suficiente para determinar a capacidade específica de combinação nem a produtividade dos híbridos.Termos para indexação: Zea mays, marcadores moleculares, dialelo parcial, capacidade de combinação, AFLP, SSR. Correlation between the heterosis of maize hybrids and genetic divergence among linesAbstract -The objective of this work was to evaluate grain yield of maize single cross hybrids obtained from diallel crosses among contrasting lines, to estimate the combining ability of the lines, and finally to confirm if the genetic diversity among those lines assessed by molecular markers is correlated with single cross hybrids heterosis. The 36 single cross hybrids resulting from partial diallel and 12 parental lines were evaluated in Campinas in randomized block design, with three replicates and two control lines checks. General combining ability of the lines was estimated according to Griffing model 4. Correlations among matrices were estimated through Mantel statistics, considering heterosis, yield and specific combining ability with genetic divergence assessed by AFLP and SSR. The hybrids PM518 x L111 exhibited an outstanding yield and the lines PM518, IP4035 and L111 showed positive general combining ability. The estimate heterosis ranged from 927 to 6,698 kg ha -1. A positive and significant correlation was observed in parental lines between heterosis and genetic diversity assessed by AFLP and SSR. The genetic divergence, however, was not enough to determine the specific combining ability and the hybrids yield.

Relationship between heterosis and genetic divergence for phosphorus use efficiency and its components in tropical maize

“…These results indicates that it is not possible to determine with accuracy, by molecular markers, if the crosses would produce hybrids with the highest heterosis for PUE or PAE. Similar results were observed by GUIMARÃES et al (2007) in maize and AGUIAR et al (2007) in Eucalyptus. According to FALCONER & MACKAY (1996) heterosis is composed of: i) dominance deviations different from zero, ii) genetic divergence and iii) complementarity. Thus, this lack of relationship between genetic dissimilarity and heterosis, can be attributed mainly to the low accuracy of the markers to predict the complementarity among the parent in crosses, ie, the low accuracy to predict the dominance deviations by molecular markers.…”

“…The lines evaluation about their combination ability is one of the most expensive steps in a maize breeding program (GUIMARÃES et al, 2007). In this sense, estimates of genetic divergence between lines by molecular markers should contribute to the formation of heterotic groups identifying hybrid combinations of higher heterotic effect and higher heterozigose.…”

“…In maize, GUIMARÃES et al, (2007) e OLIBONI et al, (2012 reported that estimates of genetic divergence were not effective at predicting the most heterotic crossings which shows that estimates of correlations between molecular variables (genetic distance) with estimates of quantitative parameters are complex, with little consistency and are difficult to interpret. However, the correlation between them is not consistent in most researchers.…”

Capacidade combinatória, divergência genética entre linhagens de milho e correlação com heterose

“…Entretanto, nem sempre a correlação entre divergência genética obtida por marcadores moleculares e desempenho do híbrido é consistente (BARBOSA et al, 2003, MELO et al, 2001, GUIMARÃES, 2007.…”

Performance of testers with different genetic structure for evaluation of maize inbred lines

“…High maize yield can be obtained by crossing of two parents that show high heterosis in hybrid combinations (CARENA & HALLAUER, 2001;GUIMARÃES et al, 2007;MIRANDA et al, 2008) and with the choice of adequate cultivars aiming to capitalize genotype x environment interaction (FRITSCHE-NETO et al, 2010a;FALUBA et al, 2010).…”