Award details

Identification, biosynthesis and associated molecular genetics of semiochemicals for a new basis of pest and disease regulation

Reference	BBS/E/C/00051545
Principal Investigator / Supervisor	Professor John Pickett
Co-Investigators / Co-Supervisors
Institution	Rothamsted Research
Department	Rothamsted Research Department
Funding type	Research
Value (£)	179,956
Status	Completed
Type	Institute Project
Start date	01/04/1997
End date	31/03/1999
Duration	24 months

Abstract

To identify semiochemicals, including pheromones and signals related to host interactions, and to provide the chemical basis for their exploitation by means of recombinant DNA techniques, particularly plant molecular genetics. Using electrophysiological techniques, directly coupled to chromatography where appropriate, in conjunction with chemical spectroscopic analysis, developed in project 051547, to identify semiochemicals for important economic pests and to some extent model organisms. Semiochemicals are targeted specifically where there is a collaborative strategy, under Programme 215 or elsewhere, for development towards commercial exploitation in the long term by recombinant DNA techniques. Chemical synthesis, using latest organic synthesis approaches, provides semiochemicals authenticated, particularly by nuclear magnetic resonance spectroscopy, for confirmation of identity. The main synthesis effort is of putative biosynthetic precursors, incorporating non- and radio-labelled isotopes, for the elucidation of biosynthetic pathways and associated enzyme purification, leading to rational molecular genetic development. The emphasis is on semiochemicals produced as secondary metabolites in higher plants, but includes certain insect pheromones where molecular structure is the same as, or is related to, plant metabolites. Short term plans involve researching towards single gene transfer between plants, principally to modify the secondary metabolism of crop plants so that existing pathways are changed in order to divert normally produced metabolites into the semiochemical target molecules. Chemical studies here also underpin the identification of tissue-specific and signal-activated promoter systems to allow expression of enzymes at appropriate sites and stages during plant growth. Such studies are on specific semiochemicals from the isoprenoid pathway acting as pheromones and host location signals for aphids (Homoptera: Aphididae). This work provides the basis for extension to pests on other major world crops incorporating semiochemicals from other pathways, particularly those related to the phenylalanine ammonia-lyase and the fatty acid lipoxygenase pathways. To define, using electrophysiology coupled gas chromatography (GC), isoprenoid semiochemicals, involved in interactions between plant/aphids/parasitoids, released during feeding and high CO2 stress. 2. To investigate further the molecular structure of specific sesquiterpene hydrocarbons shown in earlier studies to be associated with plant stress. 3. Chemical synthesis in order to investigate resource allocation for stress-related isoprenoid semiochemicals by non-radio isotopic labelling and mass spectrometry (MS). 4. To investigate biomimetic synthesis of cyclopentanoid semiochemicals with all-cis stereochemistry. 5. To synthesise radio- and non- radio isotopically labelled precursors for investigation of cyclopentanoid cyclase enzymes from Nepeta species (Lamiaceae). 6. To synthesise cold isotopically labelled citronellol for investigating biosynthesis of cyclopentanoid sex pheromone components, specifically in aphids. 7. To study further rice pest semiochemical biosynthesis and associated molecular genetics. Conduct preliminary studies on the biosynthesis of stress related isoprenoids. 2.Test the tentative structure proposed for the novel sesquiterpene hydrocarbon stress compounds. 3.Identifiy sample impurities that reduce aphid and parasitoid atrractancy of semi-biotechnological aphid sex pheromone product. 4.provide tentative new biochemical and molecular genetic targets related to plant-plant interactions.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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