A gene that confers resistance to Pythium root rot in common bean: Genetic characterization and development of molecular markers

The importance of bean (Phaseolus vulgaris) root rots caused by several Pythium species has been on the increase in the highly populated and intensively cultivated highlands of east and central Africa. Yield losses of up to 70% have been reported in Kenya and Rwanda. Few bean cultivars have been ide...

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Bibliographic Details
Published in:Phytopathology 2005-06, Vol.95 (6)
Main Authors: Mahuku, G, Buruchara, R, Navia, M, Otsyula, R
Format: Article
Language:English
Subjects:
Phaseolus vulgaris
Pythium
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Summary:The importance of bean (Phaseolus vulgaris) root rots caused by several Pythium species has been on the increase in the highly populated and intensively cultivated highlands of east and central Africa. Yield losses of up to 70% have been reported in Kenya and Rwanda. Few bean cultivars have been identified to be resistant to prevalent Pythium species. This study was undertaken to determine inheritance of resistance to Pythium root rot and identify molecular markers linked to the resistance gene in the cultivar RWR 719. Inoculation of parents, F sub(1), F sub(2) and backcross-derived populations from a cross between RWR 719 and GLP2 (susceptible) with P. ultimum var. ultimum revealed that a single dominant gene conditioned resistance. Using a combination of RAPD and simple sequence repeat (SSR) marker techniques and bulked segregant analysis on the F sub(2) population, two RAPD markers (OPAA19 and OPBE08) located at 1.5 and 4.0 cM, and one SSR marker (VHVGT) sub(5)G), that segregated in coupling phase with the resistance gene were identified. Conversion of these markers to SCARs, their validation in advanced generations of this cross as well as outside the mapping population and their suitability for marker-assisted selection to incorporate this resistance gene into popular commercial varieties is discussed.
ISSN:0031-949X