HR matching - Molecular pathotyping of parasitic nematodes to maximize agronomic lifespan of non-Hosts and host plant Resistances

For food production at an affordable price, large scale mono-crop production systems are unavoidable, but pathogens thrive is such systems. For decades, wide-spectrum pesticides have been used especially for below-ground pathogen control. Because of their highly negative impact on the environment, most of these wide-spectrum pesticides have been or will be phased out. With an estimated damage of $US 125 billion per year, plant-parasitic nematodes are probably the most harmful category of soil pathogens. Mainly because of their limited mobility in soil and their low number of generations per year, host plant resistances are a remarkably durable means to manage of this category of pathogens. The overall goal of this project is to maximize the agronomic life span of host plant resistance (R) genes by matching resistance genes with the virulence characteristics of pathogen populations at field level. This sounds obvious, but for none of agronomically relevant R genes, the corresponding pathogen effectors are known.     In this project, we will use a field pathogenomics approach to identify members of effector families that trigger three, commercially highly relevant resistances in potato: the H1 gene against two pathotypes of the potato cyst nematode (PCN) Globodera rostochiensis, Grp1, conferring resistance against a G. rostochiensis and a G. pallida pathotype, and Rmc1, a major R gene against the Columbian root-knot nematode Meloidogyne chitwoodi.  By exploiting the same principles, we will pinpoint effectors that determine host plant specificities of races of the stem nematode Ditylenchus dipsaci, a major pathogen in horticulture (including flower bulbs).   Effector domain variations that determine recognition by selected resistance proteins, or - in case of races of stem nematodes - host preferences, will serve as the very basis for affordable and specific quantitative PCR assays that will allow full exploitation of the control potential of resistant and non-host plant genotypes.