Mapping and confirmation of a new sudden death syndrome resistance QTL on linkage group D2 from the soybean genotypes PI 567374 and ‘Ripley’

Abstract

The use of resistant cultivars is the most effective method for controlling sudden death syndrome (SDS), caused by Fusarium solani f. sp. glycines (FSG) (syn. Fusarium virguliforme Akoi, O’Donnell, Homma and Lattanzi), in soybean [Glycine max (L.) Merr.]. Previous research has led to the identification of soybean genotypes with partial resistance to SDS and quantitative trait loci (QTL) controlling this resistance. The objective of our study was to map QTL conferring SDS resistance in populations developed from the crosses Ripley × Spencer (R×S-1) and PI 567374 × Omaha (P×O-1). Both Ripley and PI 567374 have partial resistance to SDS and Spencer and Omaha are susceptible. The R×S-1 population was evaluated for SDS resistance in three field environments and the P×O-1 population was greenhouse evaluated. Three SDS resistance QTL were mapped in the R×S-1 population and two in the P×O-1 population. One resistance QTL was mapped to the same location on linkage group (LG) D2 in both backgrounds. This QTL was then tested in a population of F2 plants developed through one backcross (BC1F2) in the PI 567374 source and in a population of F8 plants derived from a heterozygous F5 plant in the Ripley source. The LG D2 QTL was also significant in confirmation populations in both resistant backgrounds. Since none of the SDS resistance QTL identified in the R×S-1 or P×O-1 populations mapped to previously reported SDS resistance regions, these new QTL should be useful sources of SDS resistance for soybean breeders.