Genetic control of common bean resistance to white mold and backcross assisted by microsatellite markers / GENÃTICA DA RESISTÃNCIA DO FEIJOEIRO AO MOFO BRANCO E USO DO RETROCRUZAMENTO ASSISTIDO POR MARCADORES MICROSSATÃLITES.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The identification of sources of resistance to the white mold in common bean, and the study of its inheritance is primordial for the success of breeding programs aiming at resistant cultivars. The present research had the objectives: 1) to study the nature and the magnitude of genetic effects of resistance to white mold 2) use microsatellite (SSR) markers to accelerate the genome recovery of the recurrent parent, as well as to select plants more similar to that parent with the QTL for white mold resistance. The resistant (G122) and susceptible (M20) lines were crossed and generated the F1, F2 and F2:3 progenies. The experiment was set up using two replications in a randomized complete blocks design. The parents and the three generations were inoculated using the mycelium (Straw test) of the pathogen. Approximately 28 and 38 days after sowing and six to eight days after the inoculation, the reaction to the white mold was evaluated in each plant using a diagrammatic scale from 1 (no symptoms) to 9 (dead plant). Data were analyzed on the individual plant level and on F2:3 progeny mean. Results showed prevalence of additive effects in the trait expression and only one gene was estimated to be involved in disease control, although the character is highly influenced by environment. Wide sense heritability estimate indicates that selection is more efficient based on progeny mean and multiple inoculations. In the backcross (BC) study 267 F1BC1 plants and 113 F1BC2 plants were used. DNA was extracted from each plant of both backcrosses and from parents to obtain the SSR markers. Genetic similarity (sgij) between each BC plant and the recurrent parent was estimated using the Sorensen-Dice coefficient. The proportion of the SSR alleles derived from the recurrent parent (PR) was also estimated. Both, genetic similarity and the proportion of SSR alleles were efficient for identifying plants more similar to the recurrent parent, equivalent to BC3 and BC4. Among the 20 plants more similar to the recurrent parent it was possible to select 4F1BC1 plants with the QTL for white mold resistance and an average of 88% of PR and 2 F1BC2 plants with 91% of alleles from the recurrent parent.

ASSUNTO(S)

seleÃÃo assistida genetic control sclerotinia sclerotiorum controle genÃtico sclerotinia sclerotiorum plant breeding melhoramento vegetal assist select melhoramento de plantas

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