Protection of Crops against Insect and Fungal Pests

Crop protection is another field suffering from rapidly ermerging resistance to currently used pesticides, as was recently documented for Strobilurin, a pesticide of fungal origin. The Bioresources business area is developing new and environmentally-beneficial strategies for plant protection that pose no risks to humans or beneficial organisms such as bees. Together with university research groups, we are developing approaches based on RNA interference (RNAi) for protecting plants. RNAi involves the use of double stranded (ds)RNA to knock down the expression of selected genes with great specificity in cells and whole organisms. Our goal is to identify suitable target genes in model insects such as the red flour beetle Tribolium castaneum, and then to knock down their counterparts in pest species. Modified agricultural crops producing dsRNA corresponding to essential insect genes can selectively inhibit pests feeding on the crop and ingesting the dsRNA. The specificity of RNAi allows the development of precision tools for long-lasting protection against specific insect pests.
Several challenges remain to be addressed: the dsRNA must be absolutely specific to pest species, so we must acquire detailed genomic knowledge in several model insects to allow the identification of pest-specific target genes. The Bio-Ressources group participates in several international sequencing consortia focusing on model insect genomes e.g. the red flour beetle and the pea aphid Acyrthosiphon pisum. 50 insect genome sequences have been completed, and this allows us to screen pest insects for genes that are both species-restricted and essential for development.
Specific peptides expressed in plants represent another new and highly specific approach for protecting plants. Metchnikowin, a small peptide once identified in Drosophila, retains its antifungal activity when expressed in plants and confers complete resistance against pathogenic fungi in barley, for example, without affecting at all other, beneficial fungi.