This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Ketring, D. L. Articles by Melouk, H. A. Search for Related Content PubMed PubMed Citation Articles by Ketring, D. L. Articles by Melouk, H. A. Agricola Articles by Ketring, D. L. Articles by Melouk, H. A.

Articles

Ethylene Production and Leaflet Abscission of Three Peanut Genotypes Infected with Cercospora arachidicola Hori ^1,2

United States Department of Agriculture, Agricultural Research Service, Department of Agronomy, Oklahoma State University, Stillwater, Oklahoma 74078, Department of Plant Pathology, Oklahoma State University, Stillwater, Oklahoma 74078

Ethylene can induce abscission of leaves and other plant organs. Increased ethylene production by plant tissues can occur after invasion by microorganisms. The fungus Cercospora arachidicola Hori, attacks peanut leaflets and causes defoliation. Our objective was to determine if ethylene was involved in this defoliation. Leaves of three peanut, Arachis sp., genotypes were inoculated with C. arachidicola. Two genotypes, `Tamnut 74' and PI 109839, produced ethylene and were defoliated. The third genotype, PI 276233, a wild species, did not produce ethylene above control levels and was not defoliated. Increase in ethylene production by Tamnut 74 and PI 109839 coincided with appearance of disease symptoms. Tamnut 74 produced the most ethylene, but PI 109839 was equally defoliated. Thus, less overall ethylene production did not necessarily indicate a more resistant genotype in this system unless ethylene production remained at control levels, as it did for PI 276233. Ethylene sufficient to initiate abscission could have been produced by the seventh day after inoculation when it was similar for both Tamnut 74 and PI 109839, but 3 to 4 times control amounts. This occurred before the rapid increase in ethylene production and before disease symptoms were visible. Silver ion, a potent inhibitor of ethylene action, was sprayed at three concentrations on intact Tamnut 74 plants. All rates reduced abscission and 150 mg/liter Ag(I) decreased abscission to below 10%. The data indicate that ethylene produced by peanut leaves in response to C. arachidicola infection initiates abscission and that ethylene action can be blocked by Ag(I) in such a host-pathogen interaction.

² Mention of a trademark, proprietary product, or vendor does not constitute endorsement by the United States Department of Agriculture or Oklahoma State University and does not imply its approval to the exclusion of other products or vendors that also may be suitable.