Level and Geographical Distribution of Resistance to Meloidogyne arenaria in the U.S. Peanut Germplasm Collection
2000
Holbrook, C Corley | Stephenson, Michael G. | Johnson, A William
The peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] causes significant economic losses in many peanut (Arachis hypogaea L.) production areas of the world. The objectives of this study were (i) to examine the peanut core collection to identify sources of resistance, (ii) to estimate the level of resistance that occurs in the U.S. germplasm collection, and (iii) to examine the geographical distribution for resistance in peanut germplasm. Seven hundred forty-one accessions from the core collection were tested in greenhouse trials. The egg-mass rating for cultivar Florunner, the susceptible check, was 4.0 on a 1.0 to 5.0 scale with a nematode reproduction rate of 15496 eggs per gram of fresh root weight. Fifty-six accessions exhibited an egg-mass rating of ≤2.5. Thirty-six core accessions showed a reduction in root galling, egg-mass rating, egg count per root system, and egg count per gram of root in comparison to Florunner. Twenty-one accessions showed a 70% reduction in egg count per root system and per gram of root, and two accessions showed a 90% reduction of these variables in comparison with Florunner. The 56 resistant indicators from screening the core collection identified 39 clusters in the entire germplasm collection that should be examined more thoroughly. China and Japan appear to be valuable geographical sources for resistance to this nematode.
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