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RAPD,
SSR and AFLP markers linked to genes conferring resistance to angular
leaf spot in common bean
G. Mahuku, C. Montoya, Y. Mantilla, M.
Contreras, C. Jara & S. Beebe
Angular leaf spot of common bean, caused by the fungus, Phaeoisaiopsis
griseola Sacc., is a major disease that can cause yield losses as
high as 80%. Host resistance is the most practical strategy to manage
the disease but resistant cultivars are short-lived because P.
griseola is highly variable. Pyramiding resistance genes is a very
effective way to develop cultivars with lasting resistance but combining
several resistance genes simultaneously in one background is impossible
without markers (either physical or molecular) for each gene. The
objectives of this study were to determine the inheritance of angular
leaf spot resistance and identify random amplified fragment length
polymrphism (RAPDs), simple sequence repeats (SSR) and amplified
fragment length polymorphism (AFLP) markers linked to the resistance
genes present in three genotypes: Mexico 54, MAR 1 and G 10474.
Greenhouse evaluations of parents, F1, F2 and backcross-derived plants
showed that ALS resistance in Mexico 54 to race 31-55 and of G 10474 to
race 63-63 was conditioned by a single dominant gene. Evaluation of
parents, F2 and recombinant inbred lines (RILs) derived from crossing
MAR1 x VAX 6 revealed that ALS resistance in MAR 1 to races 31-55, 63-23
and 31-39 was conditioned by a single dominant gene. The gene in Mexico
54 was tightly linked to the RAPD marker OPE4700 and three
potential AFLP markers E-AAG/M-CAA330,
E-ACG/M-CTC310 and E-ACT/M-CAT260. The resistance
gene in MAR 1 segregated with the SSR marker (GT)n 230,
while three AFLP fragments E-AAC/M-CAG310, E-ACA/M-CTT330 and E-AAC/M-CAT285
segregated with the resistance gene in G 10474. The utility of these markers in different common bean
backgrounds, development of sequence characterised amplified region (SCAR) markers and their usefulness in marker assisted selection in breeding to
pyramid angular leaf spot resistance genes into commercial types of
common bean is discussed.
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