MODIFICATION OF THE RIBOSOMAL TARGET AND DRUG EFFLUX PUMPS: MECHANISMS OF RESISTANCE TO TRICHOTHECENE MYCOTOXINS
R MITTERBAUER1, T KARL1, M LEMMENS2, H BUERSTMAYER2 and G ADAM1
1Center of Applied Genetics, University of Agricultural Sciences (BOKU), Vienna, Austria; 2Institute for Agrobiotechnology, Tulln, Austria
Background and objectives
Results and conclusions
We have identified the mutation in the yeast ribosomal protein conferring trichothecene resistance and have introduced a plant homologue with the corresponding mutation into tobacco using Agrobacterium-mediated transformation. At present it is unclear if differences in the ribosomal resistance exist in the wheat breeding material. A restriction fragment length polymorphism between a highly sensitive and a highly resistant wheat cultivar used for generating a doubled haploid mapping population has been detected using the ribosomal protein gene as a probe.
The second mechanism, pleiotropic drug resistance mediated by broad specificity drug efflux pumps, seems to be the predominant mechanism operating in wheat. We observed a strong correlation between trichothecene resistance and resistance to other inhibitors (e.g. cycloheximide) that are substrates of the yeast ABC transporter protein encoded by the PDR5 gene. Evidence for the existence of homologous ABC transporter genes in plant genomes that most likely play a prominent role in plant defence against many toxic metabolites will be presented. Furthermore, we will report on our attempts to express the yeast PDR5 gene in tobacco.
Our identification of candidate trichothecene resistance genes could be extremely important for both classical resistance breeding strategies employing marker-assisted selection, and biotechnological approaches for improving Fusarium resistance of cereals.