Oomyceticides (fungicides) and P. infestans: discovery and resistance

Chemical control plays a key role in controlling late blight and other diseases caused by oomycete. It is estimated that more than 50% of the potato crop would be lost without chemical control. Much of our lab's research has the long-term goal of identifying pathways in the pathogen that could be targets of future crop protection chemicals (oomyceticides,commonly [but incorrectly] termed fungicides). We are also involved in projects with more short-term goals. These include studying the mechanism of action of compounds currently under development, identifying the basis of resistance, and designing assays to diagnose resistance within pathogen strains or populations.

The fungicide metalaxyl used to be very effective against P. infestans worldwide. However, the emergence of resistance to this compound has frustrated growers' ability to control late blight and other oomycete diseases. Using modern genomics-based tools, we have mapped the major gene determining resistance and developed assays for detecting resistance

SNPs linked to metalaxyl resistance.

High resolution melt analysis of SNP associated with resistance.

We are also studying how P. infestans survives stresses imposed by chemical toxicants, including fungicides. This includes characterizing ABC transporter efflux proteins, among others.

Expression of ABC transporter superfamily of P. infestans upon exposure to different chemical and growth regimes.

We also partner with chemical companies and others interested in developing new oomyceticides, or studying their modes of action. This includes testing the products of high-throughput screening assays or directed strategies using dsRNA or novel formulations.

Effects of oomyceticide on hyphal morphology.

Uptake of dsRNA using modified technique.