ISHS Acta Horticulturae 663: XI Eucarpia Symposium on Fruit Breeding and Genetics
IDENTIFICATION OF MOLECULAR MARKERS LINKED TO THE MILDEW RESISTANCE GENES PL-D AND PL-W IN APPLE |
| Authors: | C.M. James, K.M. Evans |
| Keywords: | powdery mildew, Podosphaera leucotricha, bulked segregant analysis (BSA), marker-assisted selection (MAS), Malus |
| Abstract:
The introduction of resistance to powdery mildew is a major objective of apple breeding programmes in temperate areas such as the UK. Several different major genes for mildew resistance have been identified. Combining these genes through gene pyramiding provides a more durable and robust resistance far less likely to be overcome by the pathogen. Molecular markers linked to the resistance genes enable the rapid screening of progenies by marker-assisted selection and the identification of individuals with more than one resistance gene. Two progenies derived from ‘D12’ (the source of Pl-d) and ‘White Angel’ (a crab apple containing Pl-w) were screened for resistance over six seasons. A bulked segregant approach was used to screen a set of microsatellite, AFLP and RAPD primers to identify markers linked to mildew resistance. Two microsatellites were found to be flanking Pl-w, while a third confirmed the location of Pl-w on the top of linkage group 8. Seven AFLPs were identified and two of these were developed into SCARs. Three AFLPs, a RAPD and two microsatellite markers were identified and mapped for Pl-d. One of the AFLPs was converted into a SCAR. Multiplexing the Pl-d and Pl-w SCARs has allowed selection for both genes simultaneously and individuals containing both Pl-d and Pl-w resistance markers have been identified. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
