Soybean Resistance to Soybean Cyst Nematode Race 3 Is Conditioned by an Additional Dominant Gene
- A. P. Rao-Arelli ,
- Sam C. Anand and
- Allen J. Wrather
Inheritance of resistance in soybean [Glycine max (L.) Merr.] soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is complex. The objectives of this study were to determine (i) inheritance Race 3 resistance in ‘Peking’ and PI 90763 and (ii) the relationship Rhg4 and of any other genes occurring in Peking to those genes found in PI 88788 for SCN resistance. The F1, F2, and F3 plants from five different crosses among resistant (R) and susceptible (S) cultivars evaluated for SCN resistance in the greenhouse. Individual plants were categorized as resistant or susceptible based on the index of parasitism. The chi-square test was used to determine goodness of fit between observed and expected ratios. The results indicated that SCN Race 3 resistance was conditioned by one dominant and two recessive genes in each parent. Peking and PI 90763 have all three resistance genes in common. Two genes, Rhg4 and rhgz, in both Peking and in PI 90763 were also in P1 88788. An additional dominant gene in PI 88788 and a second recessive gene in Peking and in PI 90763 provided nonallelic interaction.
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