Genetic and Molecular Insights into Mechanisms Underlying a Maize Disease

Purdue University, West Lafayette IN

Investigators

Abstract

A major goal of research on plant-pathogen interactions is to elucidate mechanisms that underlie susceptibility and resistance responses in the host, ultimately to control the impact of pathogens on the agricultural economy. A pathosystem that provides a unique opportunity to address these questions in maize involves race 1 of Cochliobolus carbonum, a fungal pathogen. This pathosystem is characterized by severe leaf blight and ear mold disease, a key mediator of which is HC-toxin, an epoxide-containing cyclic tetrapeptide. The significance of HC-toxin in disease etiology is underscored by the fact that it is the target for a disease resistance mechanism that evolved naturally in maize to counter C. carbonum race 1. This resistance mechanism operates via reduction of a key carbonyl group on HC-toxin. The modus operandi by which HC-toxin facilitates C. carbonum race 1 pathogenesis however remains unknown. Gaining an insight into this question is the objective of this proposal, which will be accomplished by a combination of genetic and genomics approaches. The genetic approach will focus on identifying and characterizing maize mutants that no longer succumb to infection by the pathogen. The genomics approach will leverage DNA microarray-based gene expression profiling to identify genes whose expression is impacted by HC-toxin during colonization by C. carbonum. The results of this project will uncover key components of the maize defense response and how these components are evaded by C. carbonum race 1 to cause disease. The knowledge and resources generated will pave the way for future advances in this area, providing a firm foundation for the development of environmentally safe and sustainable strategies for crop protection in maize as well as other cereals. This research will provide training opportunities in genetics, genomics, bioinformatics, and pathology to a postdoctoral fellow and several undergraduate students.