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United States Department of Agriculture

Agricultural Research Service

Title: Studies on the Biochemical Bsis of Resistance in Sorghum to the Chinch Bug, Blissus Leucopterus Leutopterus (Say)

Authors
item Ramnath, S - UNIVERSITY OF NEBRASKA
item Pedersen, Jeffrey
item Foster, J - UNIVERSITY OF NEBRASKA

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 12, 1996
Publication Date: N/A

Interpretive Summary: A series of experiments were conducted to determine the biochemical basis of chinch bug resistance in sorghum. Resistance factors do not appear to be water soluble. Using High Performance Liquid Chromatography (HPLC), the chinch bug resistant lines had higher concentrations of total phenolic acids than susceptible lines. When individual phenolic acids were examined, the resistant lines had higher levels of p-hydroxybenzoic, ferulic and protocatechuic acids. These acids were then tested for toxicity to the chinch bug by feeding them to chinch bugs. These bioassays indicated that p-hydroxybenzoic acid was the most toxic, and caffeic acid the least toxic, to the chinch bug. Susceptible lines had significantly lower concentrations o p- hydroxybenzoic acid and ferulic acid when compared with the resistant lines. These studies provided the basis for sorghum breeders to directly select for biochemical factors associated with chinch bug resistance.

Technical Abstract: Plant steam distillate of a resistant line of sorghum, KS94, did not possess any insecticidal properties against the chinch bug. Steam distillates of KS94 at high concentrations (2000 and 4000 ppm) elicited negative orientation responses when pearl millet plants were sprayed with the extract. Extracts of a susceptible line, Double Dwarf Yellow Milo (DDYM), did not possess any chinch bug attracting qualities. An estimation of total phenolic acids in seven sorghum lines indicated that chinch bug resistance lines had significantly higher concentrations of phenolic acids than the susceptible lines. Levels of phenolic acids increased with increase in plant age, and there were no differences in the phenolic acid profiles in the greenhouse and the growth chamber. Quantities of individual phenolic acids were estimated after separation on the High Performance Liquid Chromatography (HPLC). The resistant lines had significantly higher levels of p-hydroxybenzoic, ferulic and protocatechuic acids. Bioassays indicated that p-hydroxybenzoic acid was the most toxic, and caffeic acid the least toxic, to the chinch bug. Susceptible lines had significantly lower concentrations o p- hydroxybenzoic acid and ferulic acid when compared with the resistant lines.

Last Modified: 10/22/2014
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