On-line detection and diagnosis of plant damage and stress by herbivores and pathogens

Current world agriculture is heavily dependent on chemical inputs to deliver both nutrients for growth and pesticides and fungicides for plant health. To ensure sustainability of agriculture in the future, alternative ways have to be found to secure and increase crop yields whilst reducing the reliance on chemical resources to deliver healthy and productive crops. In Europe the range of products available to combat pest and pathogen attack has already been significantly reduced as a result of changes to EU pesticide and fungicide regulations. In addition there is increasing pressure by consumers on food suppliers and supermarkets alike, to deliver products that are pesticide-free. These drivers are now beginning to influence fundamental plant research which aims to better understand how plants respond to biotic (and abiotic) stresses, with the ultimate aim of identifying novel methods for detecting, monitoring and diagnosing biotic (and abiotic) stresses, and hence allowing more targeted approaches to chemical and other interventions. Plants produce a wide range of volatile organic chemicals (VOCs). The VOC profile for a particular plant species is unique; however that profile can change when a plant is subjected to biotic or abiotic stress. These compounds have a number of functions in plants, as signalling agents, as direct and indirect protectants against biotic stress (herbivores, pathogens) and as protectants against abiotic stresses (high temperature, oxidants). The aim of this project is to determine if it is possible to detect, diagnose and differentiate biotic and abiotic stresses in selected plant species. We have already shown this is possible at the leaf-level in preliminary work using tomato (Laothawornkitkul et al, Environ. Sci. Technol., 22, 8433 - 8438, 2008) but not at the whole plant, glass house or field scales. We will use wheat and oilseed rape as examples of field grown crops, and strawberry, often grown in the field but increasingly grown as a protected crop in the UK. Aphids will be used as the model pest, together with Botrytis as a necrotrophic pathogen and powdery mildew as a biotroph. To facilitate this work we will use the state of the art technologies of proton transfer reaction mass spectrometry (PTR-MS) and proton transfer reaction - time of flight - mass spectrometry (PTR-ToF-MS) with gas chromatography - mass spectrometry (GC-MS) for compound verification where necessary. Initially experiments will be conducted at Lancaster University using PTR-MS and GC-MS. The student will then work at Ionicon in Austria for 12 months, using their latest PTR-ToF-MS instrument, to generate more detailed mass-specific data. Whilst the student is on placement at Ionicon, opportunities will be sought for him/her to have knowledge exchange with experts in eddy covariance flux measurements at the University of Innsbruck, with a view to the possible extension of the work to the field scale. A comparison of profiles under controlled and field conditions will enable an assessment of how changing abiotic parameters impact upon the volatile profile of healthy, control plants compared to those challenged by biotic factors. In the project the student will therefore investigate and measure: the VOC profile of healthy plants; signature chemicals/profiles that designate a particular disease or pest; the level of infestation or infection required in order to detect a change in VOC profile; the impact of changing water status on VOC profiles in the presence or absence of pest or pathogens; how such profiles are modified in a 'real-world' situation where abiotic changes are uncontrolled. This will give the student training in a range of whole plant and chemical detection techniques. The project and industrial collaboration are designed not only to give first-class research training but also to produce first-class scientific output suitable for a PhD thesis.