High level of resistance to proteinase inhibitors may be conferred by proteolytic cleavage in beetle larvae

Incorporation of genes encoding proteinase inhibitors into oilseed rape genome could confer resistance to Coleoptera, which are the major pests on rape in Europe. A detailed study of the digestive proteinase of a model cruciferous-feeding Coleoptera, Phaedon cochleariae, showed that this insect reli...

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Bibliographic Details
Published in:Insect biochemistry and molecular biology 1998-04, Vol.28 (4), p.229-237
Main Authors: Girard, Cécile, Le Métayer, Martine, Bonadé-Bottino, Michel, Pham-Delègue, Minh-Hà, Jouanin, Lise
Format: Article
Language:English
Subjects:
aminopeptidase
Animals
Biochemistry, Molecular Biology
Bowman–Birk inhibitor
Chrysomelidae
Coleoptera - physiology
Crops, Agricultural - genetics
Endopeptidases - metabolism
endoprotease
Genome, Plant
Insect Control
Life Sciences
oilseed rape
Oryzacystatin I
Plants, Edible - genetics
Protease Inhibitors - metabolism
resistance
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Summary:Incorporation of genes encoding proteinase inhibitors into oilseed rape genome could confer resistance to Coleoptera, which are the major pests on rape in Europe. A detailed study of the digestive proteinase of a model cruciferous-feeding Coleoptera, Phaedon cochleariae, showed that this insect relies on a complex proteolytic system including serine, cysteine, aspartyl proteinases, and leucine aminopeptidases. The inhibition of general and specific activities by a range of proteinase inhibitors in vitro suggested that oryzacystatin I (OCI) and Bowman–Birk inhibitor (BBI) would have adverse effects when ingested by the larvae. However, the growth and the feeding of larvae reared on oilseed rape leaf discs treated with a high dose of OCI and/or BBI were not affected. Moreover, the levels and patterns of proteolytic activities were not modified in these larvae. The study of the interactions between P. cochleariae larval proteinases and OCI and BBI revealed that both inhibitors were rapidly cleaved by serine proteinases in association with leucine aminopeptidases, and consequently lost their inhibitory capacity. This mechanism of resistance is very efficient, and may be widespread among Coleoptera. The major implications for insect control using proteinase inhibitor-based strategies are discussed.
ISSN:0965-1748
1879-0240
DOI:10.1016/S0965-1748(98)00027-7