Inheritance of Resistance to the Javanese Root‐Knot Nematode in Soybean

Abstract

The inheritance of resistance in soybean [Glycine max (L.) Merr.] to the javanese root‐knot nematode [Meloidogyne javanica (Treub) Chitwood] was determined for crosses of a susceptible genotype, ‘CNS’, with three resistant genotypes, ‘Gordon’, PI80466, and PI230977. For each cross, F1, F2, and/or F3 populations were screened in a greenhouse for resistance to gall formation by counting individual galls on the roots of plants inoculated with nematode eggs. The distribution of galls for each F2 and/or F3 population was continuous. Variance component heritability estimates for the three crosses ranged from 0.23 to 0.51 on a plot basis and 0.48 to 0.76 on a mean basis. The correlation between gall number on F2 plants and mean gall number on F3 progeny (heritability on a plant basis) was 0.26 for CNS × Gordon and 0.29 for CNS × PI230977. These data suggest that resistance to M. javanica in Gordon, PI80466, and PI230977 is quantitatively inherited. The uniqueness of resistance genes was determined for crosses among Gordon, PI80466, and PI230977. Segregation for gall number within F2 populations and significant differences (P 0.05) among F3 families from each cross indicated that each resistant parent may possess M. javanica resistance genes at different loci or different alleles at the same loci. This information can be used to more efficiently develop soybean cultivars with a high level of resistance to M. javanica.