Partial Dominance of Susceptibility in Soybean to Soybean Cyst Nematode Races 3, 4, and 5
- A. P. Rao-Arelli ,
- S. C. Anand and
- G. O. Myers
Five soybean [Glycine max (L.) Merr] genotypes, each with an unrelated source of cytoplasm, were crossed to produce eight F1 hybrids including reciprocals. These were evaluated for reaction to three races of soybean cyst nematode (SCN), Heterodera glycines Ichinohe in a greenhouse. Our objectives were to: (i) evaluate soybean F1 hybrids for partial dominance of susceptibility over resistance in susceptible parents and (ii) determine the role of cytoplasm for reaction to the selected populations of SCN Races 3, 4, and 5. Single seedlings were inoculated with approximately 1000 eggs and larvae of either of the three races of SCN. Plant roots were washed after 30 d and white females counted. Occurrence of significantly (P ≤0.05) fewer number of white females on reciprocal F1s compared to the susceptible parents in six of the eight crosses studied indicated partial dominance of susceptibility. Soybean PI 88788 nuclear genes for resistance to SCN Race 4 appeared to express a significantly (P ≤0.05) different reaction in two crosses with two different susceptible parents. No significant (P ≤ 0.05) differences were observed between reciprocal crosses for SCN reaction, indicating lack of maternal/ cytoplasmic influences in the parents. These results provide additional useful information on genetics of resistance to SCN reaction.
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