Phenolic Compounds on the Pod-Surface of Pigeonpea, Cajanus cajan, Mediate Feeding Behavior of Helicoverpa armigera Larvae

Green, P W C and Stevenson, P C and Simmonds, M S J and Sharma, H C (2003) Phenolic Compounds on the Pod-Surface of Pigeonpea, Cajanus cajan, Mediate Feeding Behavior of Helicoverpa armigera Larvae. Journal of Chemical Ecology, 29 (4). pp. 811-821. ISSN 0098-0331

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Abstract

A methanol extract of the pod surfaces of Cajanus cajan, a feeding stimulant for fifth-instar Helicoverpa armigera, was shown to contain four main phenolic compounds. Three of these were identified as isoquercitrin, quercetin, and quercetin-3-methyl ether, by comparing UV spectra and HPLC retention times with authentic standards. The fourth compound was isolated by semipreparative HPLC and determined to be 3-hydroxy-4-prenyl-5- methoxystilbene-2-carboxylic acid (stilbene) by NMR spectroscopy and mass spectrometry. Quercetin, isoquercitrin, and quercetin-3-methyl did not affect the selection-behavior of fifth-instar H. armigera. However, larvae were deterred from feeding on glass-fiber disks impregnated with the stilbene. Furthermore, larvae exposed to quercetin-3-methyl ether consumed significant amounts of both disks. In a binary-choice bioassay, a combination of quercetin-3-methyl ether and the stilbene on one disk and pure quercetin-3-methyl ether on the other disk resulted in increased consumption of both glass-fiber disks by larvae. In contrast, consumption was reduced if the combination was presented to larvae on one disk with purified stilbene on the other disk. Cajanus cajan cultivars that varied in their susceptibility to H. armigera were surveyed for the presence of the four phenolic compounds. An absence of quercetin and higher concentrations of isoquercitrin than the cultivated variety characterized pod surface extracts of pod-borer-resistant cultivars. In addition, the ratio of the stilbene to quercetin-3-methyl ether was greater in the pod-borer-resistant cultivars. These findings are discussed in relation to the identification of chemical characters that can be used for crop improvement.

Item Type:	Article
Divisions:	UNSPECIFIED
CRP:	UNSPECIFIED
Uncontrolled Keywords:	Cajanus cajan, podborer, Helicoverpa armigera, feeding behavior, stilbene, quercetin-3-methyl ether, quercetin, isoquercitrin
Subjects:	Mandate crops > Pigeonpea
Depositing User:	Mr Sanat Kumar Behera
Date Deposited:	09 Oct 2011 11:56
Last Modified:	09 Dec 2011 05:22
URI:	http://oar.icrisat.org/id/eprint/2118
Official URL:	http://dx.doi.org/10.1023/A:1022971430463
Projects:	UNSPECIFIED
Funders:	Department for International Development (DFID)
Acknowledgement:	The authors are grateful to Mr. G. Pampapathy, Mr. Rakesh Kumar, Mr. V. V. Rao, Mr. Madhusan Reddy, and Mr. Raja Rao (ICRISAT) and to Miss Iranthi Methathananda (Kingston University, UK) for technical assistance. We thank Drs. N. C. Veitch, and R. J. Grayer (RBG, Kew) for NMR spectra and advice on analysis of phenolic compounds, respectively. Mrs. M. Yule and Mr. M. Gershater are thanked for their help with culturing Helicoverpa armigera at Kew. Two anonymous reviewers are also thanked for their comments on the manuscript. This project was funded by a Department for International Development (DFID) Competitive Research Facility Grant [R 7029 (C)] to ICRISAT/NRI/Kew. This work was carried out under a MAFF licence issued to Kew under the Import and Export (Plant Health, Great Britain) Order and the Plant Pest (Great Britain) Order 1993.
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