Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2006
Publication Date: 8/1/2007
Citation: Farias Neto, A.L., Hashmi, R., Schmidt, M., Carlson, S.R., Hartman, G.L., Li, S., Nelson, R.L., Diers, B.W. 2007. Mapping and Confirmation of a New Sudden Death Syndrome Resistance QTL on Linkage Group D2 from the Soybean Genotypes PI 567374 and ‘Ripley’. Molecular Breeding. 20:53-62. Interpretive Summary: The use of resistant soybean cultivars is the most effective method for controlling sudden death syndrome (SDS), caused by Fusarium virguliforme. Previous research has led to the identification of soybean genotypes with partial resistance to SDS. The objective of our study was to determine the location of genes conferring partial resistance to SDS in the variety Ripley and PI 567374 using DNA markers. These locations are known as quantitative trait loci (QTL). A common QTL for SDS resistance was found in both PI 567374 and Ripley. Additional QTL for resistance to SDS were found in both populations. The QTL identified in these populations have not been previously reported. These new QTL for SDS resistance and the DNA markers associated with them will be useful for scientists studying SDS resistance or developing SDS resistant cultivars.
Technical 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 have been identified. The objective of our study was to map QTL conferring SDS resistance in populations developed from the crosses Ripley x Spencer (RxS-1) and PI 567374 x Omaha (PxO-1). Both Ripley and PI 567374 have partial resistance to SDS and Spencer and Omaha are susceptible. The RxS-1 population was evaluated for SDS resistance in three field environments and the PxO-1 population was greenhouse evaluated. A significant QTL identified in both populations was tested in a population of F2 plants developed through one backcross (BC1F2) in the PI 567374 background and in a population of F8 plants derived from a heterozygous F5 plant in the Ripley background. Across field environments for the RxS-1 population, a SDS resistance QTL was mapped to linkage group (LG) D2 using an experiment-wise threshold of P<0.05. Using the same threshold, no significant QTL were identified in the PxO-1 population across greenhouse tests. When the experiment-wise threshold was relaxed to P<0.25, two QTL were identified. One mapped to the same region on LG D2 that was significant in the RxS-1 population and the other mapped to LG I. The LG D2 QTL was confirmed in confirmation populations in both resistant backgrounds. Since none of the SDS resistance QTL identified in the RxS-1 or PxO-1 populations mapped to previously reported SDS resistance regions, these new QTL should be useful sources of SDS resistance for soybean breeders.