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Reference Report for IND20486752
Title:Genetic mapping of soybean cyst nematode race-3 resistance loci in the soybean PI 437.654
Authors:Webb, D.M., Baltazar, B.M., Rao-Arelli, A.P., Schupp, J., Clayton, K., Keim, P., Beavis, W.D.
Source:Theor. Appl. Genet. 1995, 91(4):574-581
Abstract:Resistance to the soybean cyst nematode (SCN; Heterodera glycines) is difficult to evaluate in soyabean (Glycine max) breeding. PI437.654 has resistance to more SCN race isolates than any other known soyabean. Some 298 F6:7 recombinant-inbred lines from a cross between PI437.654 and BSR101 were screened for SCN race 3 resistance. A total of 355 RFLP markers, as well as the I locus, were genetically mapped, and these markers were evaluated for their association with resistance loci. The Rhg4 resistance locus was within 1 cM of the I locus on linkage group A. Two additional QTLs associated with SCN resistance were located within 3 cM of markers on groups G and M. These two loci were not independent because 91 of 96 lines that had a resistant-parent marker type on group G also had a resistant-parent marker type on group M. Rhg4 and the QTL on G showed a significant interaction by together providing complete resistance to SCN race 3. Individually, the QTL on G had a greater effect on resistance than did Rhg4, but neither locus alone provided a degree of resistance much different from the susceptible parent. The nearest markers to the mapped QTLs on groups A and G had allele frequencies from the resistant parent, indicating 52 resistant lines in this population, a number not significantly different from the 55 resistant lines found. Therefore, no QTLs from PI437.654 other than those mapped here are expected to be required for resistance to SCN race 3. All 50 lines that had the PI437.654 marker type at the nearest marker to each of the QTLs on groups A and G were resistant to SCN race 3. It is suggested that markers near to these QTLs can be used effectively to select for SCN race 3 resistance, thereby improving the ability to breed SCN-resistant soyabean varieties.






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