Selective Mapping of QTL Conditioning Disease Resistance in Common Bean

Abstract

Genetic markers linked with quantitative trait loci (QTL) may enable indirect selection of complex disease resistance. Construction of separate linkage maps to identify QTL for each complex disease resistance trait of common bean (Phaseolus vulgaris L.) is unfeasible, however. We investigated whether selective mapping could be used to hasten identification of random amplified polymorphic DNA (RAPD) associated with QTL conditioning bean golden mosaic virus (BGMV) or common bacterial blight (CBB) resistance. The mapping population (‘Dorado’ × XAN 176) consisted of 79 F5:7 recombinant inbred lines. A bulked segregant analysis (BSA) of as few as three individuals and selective genotyping was used. The 101 RAPDs identified between the parents were tested across resistant vs. susceptible bulks for BGMV reaction, combined greenhouse (leaf) and field reactions to CBB, and pod (greenhouse) reaction to CBB. Fourteen of 22 RAPDs selectively mapped because they cosegregated among lines within bulks, were linked with seven of the nine QTL conditioning resistance as identified by QTL mapping using all 101 RAPDs. The two QTL not identified by this approach had minor effects. BSA and selective genotyping required only about one‐third the cost and labor of completely classifying the whole population with each marker and was similarly effective for identifying RAPD markers associated with major‐effect QTL that condition disease resistance in common bean. Two‐locus models (R2), for select environments, explained 60% of the phenotypic variation in BGMV reaction, and 65, 58, and 46% of the phenotypic variation in greenhouse‐leaf, ‐pod, and field reactions to CBB. Repulsion linkages between QTL for BGMV and CBB may complicate the combination of resistance alleles for these two traits.

Present and future of quantitative trait locus analysis in plant breeding

“…The two main strategies are: selective genotyping (Lander and Botstein 1989) and pooling DNA from several individuals (Giovanoni et al 1991, Michelmore et al 1991, Pe´rez-Enciso 1998. By pooling DNA from resistant vs. susceptible individuals many large-effect disease resistance genes have been found (Michelmore 1995, Miklas et al 1996, Mestre et al 1997b because, as expected, the efficiency of these strategies relies mainly on the allele differences, the larger this difference the more efficient the pooling strategy. Given that marker alleles differing in presence/absence or intensities between pools have to be individually genotyped in the whole population, a high percentage of false positives may obscure the profitability of these strategies.…”

Tagging and mapping of genes and QTL and molecular marker-assisted selection for traits of economic importance in bean and cowpea

“…27 or PI 207262. This QTL has been identified in three independent studies Miklas et al, 1996;Nodari et al, 1993b), but no SCAR marker linked to this QTL has yet been developed for purposes of indirect selection.…”

“…phaseoli) are linked in repulsion on B10 (Fall et al, 2001), but they are not linked with the QTL for CBB resistance present on B10 LG . Located on B7, in a region that includes the phaseolin locus Phs and Asp gene conditioning seed brilliance, is a QTL for CBB resistance (Nodari et al, 1993b;Jung et al, 1996a;Miklas et al, 1996Miklas et al, , 2000a; Fig. 1).…”

Genetic mapping of resistance to bacterial blight disease in cassava (Manihot esculenta Crantz)

“…1995;Zhikang et al 1995;Jung et al 1996; sistance in cassava. Identifying markers for CBB resis- Miklas et al 1996;Thoquet et al 1996; El Attari et al tance can be used to increase the efficiency of selecting 1998). The number of markers found to be involved in resistant genotypes for use as parents in cassava breedresistance in these studies, based on greenhouse tests, ing.…”