Molecular Mechanisms Connecting Plant Defense Suppression with Magnaporthe oryzae Growth in Rice Cells

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

Blast, caused by the fungus Magnaporthe oryzae, is the most serious disease of cultivated rice and a global food security threat that annually results in a 10-30% reduction in worldwide rice yields. M. oryzae is also emerging as a major pathogen of wheat. During rice infection, dome-shaped fungal cells called appressoria form on the surface of the rice leaf and access the underlying epidermal cells. Remarkably, fungal growth in living rice cells, called biotrophy, occurs for the first days of infection without activating the robust plant defenses that normally work to keep the host plant disease-free. Yet, despite the fundamental importance of this biotrophic growth stage to crop health, little is known about how plant defense suppression and fungal growth is integrated in host cells. To address these knowledge gaps, this proposal asks: How do fungal cells thrive in rice cells? To answer this, research will be directed towards characterizing mutants of M. oryzae that are impaired in their ability to colonize rice cells in order to unlock the fundamental cellular, biochemical, and genetic regulatory mechanisms that govern the rice-fungus interaction. This work could point to much needed robust and sustainable mitigation strategies and shed light on fundamental growth processes in fungi. The proposed work will foster the molecular training of postdoctoral, graduate and undergraduate students from diverse backgrounds through active participation in tackling the real-world problem of rice blast disease. By addressing the fundamental question "What molecular mechanisms coordinate sustained fungal growth and plant defense suppression in the host cell?" This project aims to resolve substantial issues in plant pathology regarding the processes by which fungal pathogens thrive in plant cells. The stated objectives will use forward and reverse genetics, genome-wide proteomic and metabolic approaches, and live-cell imaging to define key exploitable differences in the metabolism of M. oryzae compared to host rice cells. This could lead to the development of novel crop protection strategies targeting molecular pathways that are critical for the biotrophic growth of the fungus but are not required for the normal function of the host cell, and could shed new light on the basic principles of cell growth. The educational objective will expand scientific education by stimulating undergraduates' science learning, preparing graduate students for scientific life beyond the university, and inspiring scientific interest in minority high school students.