The development of a Niemann-Pick gene-based marker in common bean (Phaseolus vulgaris L.) for the selection of common bacterial blight resistance
Common bacterial blight (CBB) is a major disease in common bean (Phaseolus vulgaris) caused by Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans. By characterizing alleles in three candidate genes within white bean line OAC Rex, a codominant molecular marker for resistance was created. The Niemann-Pick polymorphism (NPP) marker was developed to screen common beans for CBB resistance, and is anchored in a candidate resistance gene (Niemann-Pick like gene). Individuals in two segregating populations were screened for allelic state and disease susceptibility. It was found that the NPP marker is significantly more efficient (8% decrease in error rate) in comparison to other markers. Within the OAC Rex pedigree, the resistant allele for the NPP marker was found solely within progeny from the introgression of Phaseolus acutifolius into P. vulgaris. Lastly, the two additional candidate resistance genes investigated (R-genes 231733-8-004 and 231733-8-005), were found to have no exploitable polymorphisms.