Defusing mini-chromosomes—the Achilles’ heel of the wheat blast pandemic

Introduction

PANDEMIC is an ambitious high-risk/high-gain program to deliver an innovative pathogen-guided strategy for crop disease resistance. The wheat blast pandemic is a clear and present danger to global food security. It is caused by the blast fungus, Magnaporthe oryzae, which, after emerging in Brazil only ~35 years ago, has spread over the last 5 years to Southeast Asia and Africa.

Background

We discovered that all isolates of the pandemic wheat blast fungus belong to a single, asexual clonal lineage. These pandemic isolates carry a supernumerary mini-chromosome (mChr) of ~2 Mb, which encodes 19 secreted effector (virulence) proteins and renders the pandemic lineage highly virulent. We propose that this mChr is the Achilles’ heel of the pandemic fungus.

Project Goals

In PANDEMIC, my team and I will target the mChr virulence properties by gene editing and engineering of disease resistance genes that target mChr-encoded effectors. The central hypothesis of this project is that detailed knowledge about the biophysical properties of pathogen effector-host target interactions can guide bioengineering of non-transgenic disease resistance in wheat.

Methodology

To achieve our goal, we will employ a multi-disciplinary approach combining genetics, structural biology, and gene editing. Specifically, we will pursue the following objectives:

1. GENETICS: Determine the mChr-encoded effectors conferring high virulence on the pandemic wheat blast fungus.

2. BIOPHYSICS: Define the biophysical properties of effector-host target interactions.

3. IMMUNITY: Apply CRISPR/Cas gene editing to deliver innovative, non-transgenic solutions for blast disease management.

Expected Outcomes

At the completion of this project, my team and I will generate a detailed understanding of the biophysical properties of mChr-encoded effector-target protein complexes and deliver novel traits and non-transgenic solutions for developing resistance against the pandemic wheat blast fungus.