A functional genomics approach toward the understanding of plant secondary metabolism: II. Functional analysis and combinatorial biochemistry in different expression systems

A novel technology platform, developed by us, facilitates the discovery of differentially expressed genes in any plant system without pre-existing sequence knowledge and allows therefore the isolation of specific full-length cDNAs which can be further characterized by: A. Functional analysis by homologous expression In our tobacco BY-2 model system the overexpression of 22 genes resulted in three lines exhibiting an altered alkaloid accumulation pattern compared to controls. Targeted metabolite analysis is carried out by HPLC-PDA. B. Combinatorial biochemistry by heterologous expression The genes derived from the tobacco transcriptional profiling are used for the transformation of other species, too. One of the tested genes for example influences the tropane alkaloid biosynthesis, which is partly the same as for nicotine alkaloids, in Hyoscyamus muticus hairy roots. The effects on the completely different terpenoid indole alkaloids in Catharanthus roseus hairy roots are also investigated. GC- and LC-systems are used for the analysis of alkaloids.