Other grantholders

Rob Verpoorte, University of Leiden, The Netherlands
Cathie R. Martin, John Innes Centre, United Kingdom
Alisdair R. Fernie, Max Planck Institute for Molecular Plant Physiology, Germany

Despite the general belief that a successful applied genomics project requires a combination of molecular, genetic, metabolomic and ecological approaches our programme is one of the first to integrate this range of expertise. We intend to study a phenolic compound, chlorogenic acid (CGA), which acts as an antioxidant in plants and is expected to protect against degenerative, age related diseases. While most studies on CGA have focussed on human health aspects, our programme will study the importance of CGA for plant resistance against herbivorous insects. Specifically we want: 1) to develop tomato lines resistant to western flower thrips (Frankliniella occidentalis) by increasing natural CGA levels, 2) to explore the natural variation in CGA levels in tomatoes, 3) to identify the genetics behind CGA production levels, 4) to understand the relationship of CGA biosynthesis to other primary and secondary metabolite pathways, 5) to increase our understanding of the role of CGA in thrips resistance, in particular to identify possible synergy of CGA with other (phenolic) compounds and to determine the activity of various other cinnamic acid esters against thrips. The excessive use of pesticides has led to resistance of WFT to various insecticides and to residue problems on marketable crops. Host-plant resistance to thrips will, therefore, be an important contribution towards economic, environmental and health benefits.

Plant Ecology, Leiden (P.G.L. Klinkhamer):
The necessary pre-experiments to standardize thrips bioassays and to combine these with metabolomic measurements have been successfully accomplished. In this regard a whole plant as well as a leaf thrips bioassay has been established. Also, different thrips rearing methods to allow for rearing of different thrips biotypes have been successfully established. An experiment to study induction of CGA by thrips has been executed and the results are under analysis. The study of the natural variation of thrips resistance and CGA contents of wild and cultivated tomatoes has been conducted. Wild tomatoes had half as much thrips damage as cultivated ones. Within the wild tomatoes lines differed significantly in thrips damage, while the cultivated tomato lines did not differ in thrips damage. Leaf material of this experiment is now used for a NMR analysis. Furthermore, the genetically engineered tomatoes of C. Martin with doubled CGA contents are under investigation for thrips resistance as well as genetically engineered tomatoes of A. Fernie, with doubled CGA contents following inhibition of the mitochondrial citrate synthase.

Plant Metabolomics, Leiden (R. Verpoorte):
NMR analysis of tomato leaves has been successfully established. Furthermore, a method for the isolation of cinnamic esters has been developed. This allowed the isolation of the isomers of CGA as well as various cinnamic acid esters from plant materials. However, the amounts gained are still insufficient to be incorporated into an in-vitro thrips bioassay.

Cell and Developmental Biology (C. Martin):
Genetic engineering using the transcription factor AtMYB12 to increase CGA levels in tomato 20 fold is underway. Fruit specific lines with increased CGA levels are already available. Current work concentrates on increasing CGA levels also in the vegetative tomato parts.

Molecular Physiology (A. Fernie):
Profiling of CGA alongside a wide spectrum of primary metabolites for the introgression lines is currently under way.