DM (Dennie) te Molder BSc

Research:

Plant pathogenic nematodes are the most important biotic threat to global agricultural productivity. Disease control mainly relies on the use of quarantine measures, crop rotation schemes, and resistant cultivars. Efficient use of these methods requires an understanding of the distribution, diversity, and dispersal abilities of these pests. These characteristics are not readily apparent for microscopic organisms such as nematodes and are therefore studied through population genetics. We examine the population structure and the forces that shape this structure over time trough spatiotemporal sampling efforts and genetic selection experiments, which are combined with next generation sequencing to measure the changes in allele frequencies.

One of the important plant pathogenic nematodes that we are studying trough these means is the stem nematode Ditylenchus dipsaci. Stem nematodes can infect over 500 different plant species that include a wide range of both crops and weeds, making it difficult to design effective crop rotation schemes. However, research indicates that D. dipsaci can be subdivided into multiple (sub)species, that although morphologically indiscernible, have differing host ranges. Earlier efforts resulted in the conceptualisation of over 30 “host races”, but these races do not seem to be supported by a genetic basis and have only been of limited use in disease management. By employing a population genetics approach we hope to retire the dated notion of “host races” and replace it with a genetically founded subdivision that will help farmers design better crop rotation schemes.