Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2008
Publication Date: July 27, 2008
Citation: Arelli, P.R., Young, L.D., Concibido, V.C. 2008. Inheritance of Resistance in Soybean PI 567516C to LY1 Nematode Population Infecting cv. Hartwig. Euphytica. 151:38-41 Interpretive Summary: Soybean yields worldwide are limited by the soybean cyst nematode (SCN), a microscopic-size worm attacking the roots of the plant. Resistant cultivars have been the most effective means of controlling the pest. The majority of resistant cultivars trace their resistance to soybean lines Peking and/or PI 88788. Nematode populations are variable and have adapted to reproduce on resistant cultivars. Soybean cultivar Hartwig was released which has comprehensive resistance to most SCN populations. A virulent SCN population called LY1was recently selected for its reproduction on Hartwig. LY1 infects currently known sources of resistance except soybean PI 567516C. This resistant soybean originating in Shandong Province of China is a unique source of resistance. Resistance to LY1 nematodes in PI 567516C is controlled by three major genes. This new information on the number of genes controlling resistance to the pest will help soybean breeders develop new cultivars with better resistance to the nematode.
Technical Abstract: Worldwide, cyst nematode (SCN: Heterodera glycines Ichinohe) is the most destructive pathogen on soybean [Glycine max (L.) Merr.]. In the USA yield losses in 2001 were estimated to be nearly sixty million dollars. Crop losses are primarily reduced by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars over time because resistance primarily traces to two soybean accessions. Recently cv. Hartwig was released with comprehensive resistance to most nematode populations. A virulent SCN population LY1 was recently selected for its reproduction on Hartwig. LY1 population originated from a mass mating of SCN Race 2 (HG Type 1.2.5-) with Race 5 (HG Type 1.2-) males. LY1 nematode population infects currently known sources of resistance except PI 567516C. The female indices obtained on PI 567516C and Hartwig were 7% (resistant) and 155% (susceptible), respectively. However, the genetic basis of LY1 resistance in soybean PI 567516C is not known. Resistant PI line 567516C was crossed to the susceptible cultivar Hartwig to generate 105 F2:5 families. These families together with parents, seven indicator lines and a susceptible control cv. Lee-74 were evaluated for response to LY1 nematode population in the greenhouse. Chi-square analysis showed resistance in PI 567516C was conditioned by one dominant and two recessive genes (Rhg, rhg, rhg). Chi-square value was 0.15 and p=0.70. This information will be useful to soybean breeders for developing resistant cultivars to nematode population that infects Hartwig.