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United States Department of Agriculture

Agricultural Research Service

Title: Mass Spectral Characterization of Fatty Acid Amides from Alfalfa Trichomes and Their Deterrency Against the Potato Leafhopper

Authors
item Ranger, C - UNIV OF MO-COLUMBIA
item Backus, Elaine
item Winter, R - UNIV OF MO-ST LOUIS
item Rottinghaus, G - UNIV OF MO-COLOUMBA
item Johnson, D - CAL/WEST SEEDS, INC

Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2004
Publication Date: January 12, 2005
Citation: Ranger, C.M., Backus, E.A., Winter, R.K., Rottinghaus, G.E., Johnson, D., 2005. Mass spectral characterization of fatty acid amides from alfalfa trichomes and their deterrency against the potato leafhopper. Phytochemistry. 66:529-542

Interpretive Summary: A series of chemically related fatty acids were identified as major components of glandular trichome extracts from Medicago sativa G98A, an alfalfa genotype resistant to the potato leafhopper, Empoasca fabae. A second series of chemically related fatty acids were minor components. Saturated free fatty acids were present in trace amounts, as was an amide of linoleic acid. These compounds were synthesized and bioassayed for leafhopper deterrence by application to the surface of a sachet containing an artificial diet. Leafhoppers were then offered a two-way choice between diet surfaces treated with the synthetic amides or an untreated control. Neither the amides nor the fatty acids deterred leafhopper settling in a dose-dependent fashion. In contrast, when tested singly, the amide of linoleic acid exhibited dose-dependent deterrence against leafhopper settling. Fatty acid amides localized in alfalfa glandular trichomes may contribute to leafhopper resistance, and therefore may provide a trait for alfalfa breeders to emphasize in their selections for improved resistance.

Technical Abstract: A homologous series of N-(3-methylbutyl)amides of normal saturated C14, C15, C16, C17 and C18 fatty acids were identified as major components of glandular trichome extracts from Medicago sativa G98A, an alfalfa genotype resistant to the potato leafhopper, Empoasca fabae. A second homologous series of N-(2-methylpropyl)amides of C14 through C18 normal fatty acids were minor components. Saturated free fatty acids C12, C13, C14, C15, C16, C17 and C18 were present in trace amounts, as was the N-(3-methylbutyl)amide of linoleic acid (C18:2). N-(3-methylbutyl)amides and N-(2-methylpropyl)amides of C14 through C18 fatty acids, along with the N-(3-methylbutyl)amide of linoleic acid, were synthesized and bioassayed for leafhopper deterrence by applying the compounds to the surface of a sachet containing an artificial diet. Leafhoppers were then offered a two-way choice between diet surfaces treated with the synthetic amides or an untreated control. N-(3-methylbutyl)amides and N-(2-methylpropyl)amides of C14 through C18 fatty acids did not deter leafhopper settling in a dose-dependent fashion. In contrast, when tested singly, N-(3-methylbutyl)amide of linoleic acid exhibited dose-dependent deterrence against leafhopper settling. Fatty acid amides localized in alfalfa glandular trichomes may contribute to leafhopper resistance.

Last Modified: 10/22/2014
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