Spodoptera caterpillars neutralize maize chemical defenses by converting a toxic 1,4-benzoxazin-3-one breakdown product to non-toxic 3-ß-D-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc)

Sunday, November 16, 2014: 2:03 PM
F152 (Oregon Convention Center)
Daniel Maag , Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
Claudio Dalvit , Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Neuchâtel, Switzerland
Damien Thevenet , Laboratory of Organic Chemistry, University of Neuchâtel, Neuchâtel, Switzerland
Angela Köhler , Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
Felipe Wouters , Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
Daniel Vassão , Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
Jonathan Gershenzon , Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
Jean-Luc Wolfender , Laboratory of Phytochemistry and Bioactive Natural Products, University of Geneva, Geneva, Switzerland
Ted C. J. Turlings , University of Neuchâtel, Neuchâtel, Switzerland
Matthias Erb , Institute of Plant Sciences, University of Bern, Bern, Switzerland
Gaetan Glauser , Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
It is increasingly evident that the successes of insect pests on crops are largely due to their ability to cope with the chemical defenses of these plants. A good understanding of the mechanisms that are involved should open ways for new pest control strategies. Maize plants produce 1,4-benzoxazin-3-ones (BXs), which are stored as weakly active glucosides in the vacuole. Upon tissue disruption, BXs come into contact with β-glucosidases, resulting in the release of toxic aglycones and their breakdown products. While certain specialist herbivores are able to successfully inactivate these aglycones via reglucosylation, little is known about how they detoxify BX breakdown products. Here we report on the structure of a novel N-glucoside, 3-β-D-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc), purified from Spodoptera frugiperda feces. In vitro assays showed that MBOA-N-Glc is formed enzymatically in the insect gut using the BX breakdown product 6-methoxy-2-benzoxazolinone (MBOA) as precursor. A comparison between three maize pests that differ in their feeding behavior revealed distinct detoxification capacities. The two leaf-feeding species S. frugiperda and Spodoptera littoralis, which can defoliate well-defended maize seedlings, excreted high amounts of MBOA-N-Glc in their frass. By contrast, stem-boring Ostrinia nubilalis larvae, which infest maize plants at later growth stages and therefore experience considerably lower amounts of BXs, were hardly able to glucosylate MBOA. In feeding assays it was confirmed that MBOA had a negative effect on the growth of O. nubilalis, but not on the two Spodoptera species. In conclusion, glucosylation of MBOA is an important detoxification mechanism of BX breakdown products that helps Spodoptera spp. tolerate maize BXs.

Maag D., Dalvit C., Thevenet D., Köhler A., Wouters F.C., Vassão D.G., Gershenzon J., Wolfender J.L., Turlings T.C.J., Erb M., Glauser G. 2014. 3-ß-D-Glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc) is an insect detoxification product of maize 1,4-benzoxazin-3-ones. Phytochemistry 102:97-105.

See more of: TMP's, P-IE Section: Host Plant Resistance
See more of: Ten Minute Paper (TMP) Oral
<< Previous Presentation | Next Presentation >>

ESA Annual Meetings