Abstract
Rust, caused by the fungus Uromyces appendiculatus, may cause a significant loss to common bean (Phaseolus vulgaris L.) yield. RAPD markers tightly linked to the resistance genes may be used in breeding programs to aid the development of rust-resistant bean cultivars. In this sense, the objective of the present work was to identify RAPD markers linked to a rust resistance gene block present in the cultivar Ouro Negro. Two hundred and fourteen F2 individuals from a cross between the resistant cultivar Ouro Negro and the susceptible cultivar US Pinto 111 were inoculated with a mixture of eight races of U. appendiculatus. The segregation ratio obtained suggested that resistance is monogenic and dominant. Bulked segregant analysis was used in conjunction with the RAPD technique to search for markers linked to rust resistance genes. Two molecular markers flanking the rust resistance gene block were identified, one at 5.8 ± 1.6 cM (OX11(630)) and the other at 7.7 ± 1.7 cM (OF10(1,050)) of the gene. Simulated indirect selection efficiency in the F2 population using the two markers was 100%. The molecular markers identified in this work are currently being used for the selection of disease-resistant plants in the commom bean breeding program of the Federal University of Viçosa.
Highlights
The common bean (Phaseolus vulgaris L.) is susceptible to be attacked by a large number of pathogens which may qualitatively and quantitatively affect plant growth and yield (Vieira, 1983; Stavely and Pastor-Corrales, 1994)
Rust caused by the fungus Uromyces appendiculatus may cause a significant loss of yield (Lindgren et al, 1995)
The objective of the present work was to identify Random amplified polymorphic DNA (RAPD) markers linked to a rust resistance gene block present in the cultivar Ouro Negro, one of the major rust resistance sources used in the bean breeding program of the Federal University of Viçosa, MG, Brazil
Summary
The common bean (Phaseolus vulgaris L.) is susceptible to be attacked by a large number of pathogens which may qualitatively and quantitatively affect plant growth and yield (Vieira, 1983; Stavely and Pastor-Corrales, 1994). Fungicides and resistant cultivars are useful for limiting the progress of this disease (Stavely and Pastor-Corrales, 1994). Chemicals contaminate the environment and affect human health. For these reasons, the use of resistant cultivars is preferred by most plant breeders and researchers because they provide an effective, safe and inexpensive method of rust control
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