Bulked segregant analysis identifies molecular markers linked to Melampsora medusae resistance in Populus deltoides

Abstract

In the north central United States, leaf rust caused by Melampsora medusae is a major disease problem on Populus deltoides. In this study we identified molecular markers linked to a M. medusae resistance locus (Lrd1) that was segregating 1:1 within an intraspecific P. deltoides family (C9425DD). Previous field results were contiied in the controlled environment of a growth chamber through an excised whole-leaf inoculation method. Using bulked segregant analysis we identified two random amplified polymorphic DNA (RAPD) markers (OPG10₃₄₀ and OPZ19₁₈₀₀ that are linked to Lrd1. Based on segregation in a total of 116 progeny, the genetic distances between OPG10₃₄₀ and OPZ19₁₈₀₀ and the resistance locus were estimated as 2.6 and 7.4 Haldane centimorgans (cM), respectively. Multipoint linkage analyses strongly suggest the most likely order for these loci is Lrd1, OPG10₃₄₀ and OPZ19₁₈₀₀. These markers may prove to be instrumental in the eventual cloning of Lrd1, as well as for marker-assisted selection of leaf-rust resistant genotypes.

Citation

Tabor, G. M.; Kubisiak, Thomas L.; Klopfenstein, N. B.; Hall, R. B.; McNabb, Henry S., Jr. 2000. Bulked segregant analysis identifies molecular markers linked to Melampsora medusae resistance in Populus deltoides. Phytopathology. 90: 1039-1042.