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Signalling insect peptides as natural insecticides for crop protection (sips)

Contract nr: FAIR-CT96-1648
Project nr: 1648
Project type: SC
Starting date: 01/01/1997
Duration: 39 months
Total cost: 1,447,000 EUR
EC Contribution: 1,298,000 EUR
Scientific Officer: Arnaud BORCHARD
Research topic: Plant health
Acronym: INSECT PEPTIDES AS INSECTICIDE

Background:
Modern agriculture faces the challenge of securing the food supply in an environmentally compatible manner. Weeds, diseases and pests are among the most serious problems threatening the production of a successful harvest. The tools at the disposal of the farmer to combat insects include adapted crop varieties and pest management programmes. Breeding for insect resistant crop varieties is often hampered by a lack of resistance alleles present in the germplasm. The use of chemical insecticides (and pesticides in general) is coming under increasing criticism, because of potential environmental problems which may accrue. Biological controls with baculovirus, bacteria, fungi or parasitic wasps, represent less than 1% of the chemical insecticide sales and are only applicable in specific circumstances. Bacillus thuringiensis toxins are now widely used. However, the major threat to the Bt-plant technology, although very successful at this moment, is the potential of insect populations to develop resistance (Van Rie et al., 1995). This is the right time to proceed with the research to find novel insecticidal toxins as alternatives for Bt-toxins, as Bt-resistance could become a major problem.

Objectives:
In this project we propose to:
1) study and select signalling insect peptides which enter the hemolymph upon oral administration;
2) design and synthesise peptide analogues for improved stability and gut transition;
3) improve the already established expression in tomatoes of a synthetic gene coding for the insect peptide proctolin, and realise the plant expression of the allatostatin gene;
4) develop and evaluate transgenic crops expressing insect peptides which are orally active.
The resulting insect tolerant crop varieties will contribute to the effort of developing environmentally friendly, sustainable agriculture. This goal fits the CAP, promotes plant health, reduces farmers' inputs and, in general, should be more acceptable to the consumer than some current practices.

Description:
The overall goal of the proposed project is to develop a novel way to control insect pests. The project will assess the feasibility of protecting crops from insect attacks by expressing naturally occurring insect signalling peptides in plants. In this project we propose to explore an alternative approach for generating insect tolerant crop varieties. Since 1985, insect physiologists have discovered about 100 different insect signalling peptides. We have identified a set of such peptides, which we think have the potential to become a new class of insecticides. These peptides control different physiological processes, such as inhibition of ecdysone synthesis, inhibition of juvenile hormone synthesis, stimulation of cardiac muscle activity, inhibition of gut motility, etc. The development of insects exposed to such peptides in unphysiological dosages, or at unusual times, is dramatically disturbed and can lead to growth inhibition and death. The question is, of course, whether peptides can survive in the gut environment, pass through the gut wall, enter the hemolymph and still maintain their biological activity. A few papers showing that this is indeed the case have already been published.

Current situation/results:
Numerous peptides and analogues have been synthesised and were used in feeding and injection assays with different insect species. It could be shown that some peptides were active even following oral application. This indicates that some neuropeptides withstand proteolysis in the midgut and are able to penetrate through the gut into the hemolymph. This could also be followed using tritiated peptides in in vivo and in vitro experiments. We also gained important information on the active core of the peptides and the effects of sequence modifications (shortening, prolongation etc.) on their biological activity.
Work was also initiated on the characterisation of proteolytic enzymes in the hemolymph. Several important peptidases in the gut of different insect species could be already identified. With the help of 3H-labelled peptides, we have been able to follow the time course of peptide degradation in vitro and in vivo and identify most of the proteolytic fragments.
The expression of genes encoding selected signalling peptides has been successful in different plant species. The resulting transgenic plants were grown and tested for their biological activity. Further assays using the plant extracts, as well as detection of the produced peptides by mass spectrometry, are still in progress.


Coordinator
Jeroen VAN RIE
Aventis CropScience N.V.
Jozef Plateaustraat 22
B-9000 Gent
Tel.: +32 9 235 84 89
Fax: +32 9 224 06 94
E-mail: jeroen.vanrie@aventis.com


Partners

  • Geoffrey Mason COAST
    University of London
    Birkbeck College
    Malet Street
    UK-WC1E 7HX London
    Tel.: +44 1716 31 62 45
    Fax: +44 1716 31 62 46
    E-mail: g.coast@biol.bbk.ac.uk
  • Arnold DE LOOF
    Katholieke Universiteit Leuven
    Naamsestraat 59
    B-3000 Leuven
    Tel.: +32 16 32 39 12
    Fax: +32 16 32 39 02
    E-mail: arnold.deloof@bio.kuleuven.ac.be
  • Constantin POULOS
    University of Patras
    Dept. of Chemistry
    Organic Chemistry, Biochemistry and Natural Products Division
    GR-26500 Patras
    Tel.: +30 61 99 71 72
    Fax: +30 61 99 71 18
    E-mail: c.poulos@upatras.gr
  • Rosa RAO
    Università degli Studi di Napoli - Frederico II
    Dept. of Agronomy and Plant Genetics
    Via Universita 100
    I-80055 Portici (Napoli)
    Tel.: +39 081 77 88 54 44
    Fax: +39 081 77 53 579
    E-mail: rao@ds.unina.it

 
 
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