The approach

 

By producing an F2 generation of the hybrids between Jacobaea vulgaris and Jacobaea aquatica we generated maximal (genetic) variation of relevant ecological traits against an, on average, equal genetic background.

More than hundred lines of the F2 hybrids are kept in tissue culture which gives the opportunity of unlimited multiplication and hence measurements on the same genotypes. For high resolution mapping the number of F1 and F2 lines can be extended endlessly as also the F1 and the parental lines are maintained. 
Upto now more than 5000 partial cDNA’s have been sequenced, showing more than 400 SNP’s. The SNP’s discovered in these cDNA’s will be used to complement the genetic map based on other dominant markers and be an extra aid to discover ecologically important genes. 

one of the many hybridsBecause all the lines are in tissue culture we can use the same genotypes in all experiments and produce a database with all relevant molecular, metabolic and ecological information. We will measure the fitness of the plants under different forms and levels of herbivory, both under controlled conditions and in the habitats of the parental species, and relate this to the metabolome of the plant.

We can detect markers related to plant resistance using QTL-analysis. Similarly we can detect defence related metabolites by e.g. NMR-analysis and search for QTLs for these metabolites. The importance of the identified QTLs will further be studied in bioassays.

QTL analysis will show if the fitness-related molecular markers are likely to represent genes coding for the identified compounds. With this knowledge we can use (selected sets of)  F2-hybrids to study selection in the natural habitat.