Rhizobacterial volatiles: structure elucidation and impact on gene expression in Arabidopsis thaliana

• Applicants: Professor Dr. Wittko Francke (†); Professorin Dr. Birgit Piechulla
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 73053051

Rhizobacterial volatiles inhibit the growth of many fungi and Arabidopsis thaliana. The cytotoxic effects are caused by organic volatiles released by Stenotrophomonas, Serratia and Pseudomonas species. Recently, we identified and synthesized a polymethylated bicyclic hydrocarbon, 1,2,4,5,6,7,8- heptamethyl-3-methylenebicyclo[3.2.1]oct-6-ene (which we like to term: ‘sodoferin’), showing a new, unique carbon skeleton, but the structures of many volatiles that affect growth of plants and microorganisms are still unknown. Therefore, a primary goal of this application aims at structure elucidation and synthesis of these compounds. Synthetic samples (pure substances as well as mixtures) and isolated natural volatiles will be tested to understand their biological functions. The response at the level of gene expression using full genome microarrays will highlight genes that are up- and down-regulated after bacterial VOC fumigation in A. thaliana. T–DNA A.t. knockout mutants corresponding to genes of interest will be selected accordingly, to elucidate the modes of action, target sites and signalling pathways addressed by the bacterial volatiles. A mutant screen will be initated to reveal new target sites. The proposed project aims at the elucidation of new interaction/ communication patterns between plants and bacteria and will add new facets to the understanding of resistance mechanisms that can be useful in plant protection and plant biotechnology.

• DFG Programme: Research Grants