Wednesday, 9 November 2005

Epistatic Gene Interaction in QTLs of Soybean Seed Characters.

Johann Vollmann1, Apanee Pokeprasert1, Gertraud Stift2, and Tamas Lelley2. (1) BOKU University, Department of Applied Plant Sciences and Plant Biotechnology, Gregor Mendel Str. 33, A-1180, Vienna, Austria, (2) Department of Agrobiotechnology (IFA Tulln), Konrad Lorenzstr. 20, Tulln, A-3430, Austria

Epistasis is considered to be an important feature of quantitative performance in self-pollinated (homozygous) crop species. A bi-parental segregating population between two early maturity soybean parents (Ma.Belle x Proto) consisting of 82 F2-families had initially been analysed with a large number of polymorphic SSR markers, and QTL effects in seed characters had been reported. In the F6 generation, 5 to 8 different lines were derived from each F2 family, and a total of 530 homozygous lines was evaluated phenotypically in four environments and re-genotyped using 29 SSR markers associated with QTLs in the initial analysis. Using analysis of variance for testing of associations, about 10 QTLs were found for 1000-seed weight and several others for seed protein and oil content, respectively. The presence of 1000-seed weight QTLs on soybean linkage group O was confirmed. Two-way analysis of variance revealed a number of highly significant interactions between markers, indicating epistatic gene interaction. Significant interactions have been found both between QTL regions as well as between regions without a significant main effect. Similar to QTL main effects, some epistatic QTL effects were stable across environments, whereas for others a significant epistasis x environment interaction effect was present. In 1000-seed weight, the phenotypic effect of particular epistatic QTLs was clearly larger than the effect of the main QTLs found. The present results suggest, that epistatic gene interaction has a considerable impact on the genetics of 1000-seed weight of soybean.

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