|SLEPER, DAVID - University Of Missouri|
|SHANNON, J. GROVER|
Submitted to: Crop Science
Publication Type: Review Article
Publication Acceptance Date: 4/29/2006
Publication Date: 12/10/2006
Citation: Guo, B., Sleper, D., Lu, P., Shannon, J., Guyen, H.N., Arelli, P.R. 2006. QTLS associated with resistance to soybean cyst nematode: Meta-analysis of QTL locations. Crop Science. 46:595-602.
Interpretive Summary: Worldwide soybean cyst nematode is a major pest on soybean crop. To reduce crop losses growers plant resistant cultivars. All resistant cultivars grown today have derived their resistance primarily from two sources, Peking and/or PI 88788. Nematodes have adapted to both the sources of resistance. Understanding genetic mechanisms of resistance is most important for developing cultivars with durable resistance. Traditional methods have not explained adequately these mechanisms. Recently advanced genetic studies on several new sources of nematode resistance have been conducted in soybean. All these studies used a method called as quantitative trait (gene) analysis for nematode resistance and identified several genes. These genes need to be categorized based on their utility in breeding cultivars for durable resistance. We used a new analysis called as Meta-analysis and classified resistance genes into suggestive or significant. Soybean breeders now may selectively choose genes (QTLs) for nematode resistance and develop cultivars with durable resistance.
Technical Abstract: Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is the most important pest of soybean (Glycine max (L.) Merr) in the world. A total of 17 quantitative trait locus (QTL) mapping papers and 62 marker-QTL associations have been reported for resistance to soybean cyst nematode in soybean. Conflicting results often occurred. The objectives of this study were to : (1) evaluate evidence for reported marker-QTL associations for resistance to SCN in soybean and (2) extract relatively reliable and useful information from the reported marker-QTL associations in soybean. A meta-analysis was conducted for QTL locations by comparing the 95% confidence intervals of the reported QTLs. QTLs for different races or different studies were classified into one cluster if their confidence intervals had a region in common. The QTLs of the same cluster may have a shared locus. QTLs for different races or different studies were classified into different clusters if their confidence regions had no region in common and were greater than or equal to 20 cM away from each other. Different clusters may represent different loci. Reported SCN resistant QTLs were classified into three categories: suggestive, significant and confirmed. Confirmed QTLs are credible and can be candidates for fine mapping and gene cloning. QTLs on linkage groups (LGS) G, A2, B1, E and J were classified as confirmed. Two clusters of QTLs were identified on LG G. One of them is rhg1. One cluster of QTLs was identified near the end of LG B1 but one QTL may exist around the middle of LG B1. One cluster of QTLs was identified on LGs A2, E and J, respectively. QTLs on LGs B2, C1, C2, D1a, D2, L, M and N were classified into suggestive or significant. Confirmation studies are needed to lend credibility for these QTLs. A relationship between soybean QTLs and SCN races is discussed