Development of an Antiserum to Quantify Aphanomyces euteiches in Resistant Pea Lines. JOHN M. KRAFT, Supervisory Research Plant Pathologist,Vegetable and Forage Crops Production, Agricultural Research Services, U.S. Department of Agriculture, Route 2, Box 2953A, Prosser, WA 99350-9687. WILLIAM L. BOGE, Biological Science Laboratory Technician, Vegetable and Forage Crops Production, Agricultural Research Service, U.S. Department of Agriculture, Route 2, Box 2953A, Prosser, WA 99350-9687. Plant Dis. 78:179-183. Accepted for publication 2 November 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0179.

A polyclonal antiserum was developed that strongly reacted with antigens produced by mycelia and zoospores of Aphanomyces euteiches. The antiserum did not react with antigens produced by species of Phytophthora, Fusarium, and Pythium (except for a slight reaction with antigens produced by P. ultimum) and by Rhizoctonia solani AG-4. Resistant and susceptible pea (Pisum sativum) lines were compared for response to A. euteiches development by assaying inoculated roots using this antiserum. There was a slower buildup of A. euteiches in taproots of the resistant germ plasm lines 86-2236 and 90-2131 and PI 180693 when exposed to 100 zoospores per milliliter after 7 days. After 9 days and an inoculum level of either 100 or 1,000 zoospores per milliliter, only PI 180693 and line 90-2131 were resistant, as indicated by lower ELISA readings (A405nm). The ELISA response was linear with increasing amounts of antigen. The results showed that in resistant pea roots, growth of A. euteiches within inoculated tissues was inhibited.

Keyword(s): common root rot, resistance