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1) Evolution of Conidiation

Fungal asexual sporulation (conidiation) provides a mechanism for dispersal and dormancy. This developmental process is widespread among the Ascomycete fungi. We are testing models for the evolution of this dispersal process. There is evidence for sporulation in a common ancestor that has been modified to give rise to the variety of form and function seen in the modern lineages of the Ascomycetes. At the same time there is evidence that conidiation has evolved to use lineage-specific regulators, such that different regulatory genes were recruited to control conidial morphogenesis in different fungal lineages. Our hypothesis is that both divergent and convergent evolution have contributed to the genetic pathways governing conidiation.

NSF IOB Funded in collaboration with Dr. Dan Ebbole and Dr. Heather Wilkinson

2) Characterization of Virulence Mechanism in Pathogenic Fungi Associated with Maize Stalk Rot

Stalk rot is the most devastating disease of maize in the US. Despite the significance of the problems due to stalk rots, we have gained little ground in understanding this complex disease. Studies conducted by the PI demonstrated that Fsr1, a multimodular protein in stalk rot pathogen Fusarium verticillioides, is a virulence determinant that regulates host recognition and pathogenesis in maize-pathogen interaction. The long-term goal of this research project is to identify fungal genes and pathways associated with stalk rot pathogenesis. The Fsr1-mediated virulence in F. verticillioides provides a unique opportunity to explore the novel signaling mechanism that controls virulence in maize stalk rot pathogens. Our central hypothesis is that Fsr1 regulates virulence in maize stalk rot pathogens. The aims of this proposal are i) to characterize a novel virulence mechanism in F. verticillioides that is involved in Fusarium stalk rot pathogenesis and ii) to demonstrate that this virulence mechanism is conserved in another stalk rot pathogen, Colletotrichum graminicola. This research will provide new avenues for investigating the virulence mechanisms in pathogenic fungi, which will in turn impact the potential for innovative management strategies.

USDA NRI funded: in collaboration with Dr. Won Bo Shim.

3) Development of Microbial Bioenergy Platform

Texas Agricultural Experiment Station Bioenergy Initiative funded: in collaboration in collaboration with: Dr. Paul de figueiredo, Dr. Zivko Nikolov, Dr. Marty Dickman, Dr. Eliezer Louzada, and Dr. Tom Bianchi.

4) Characterization of Polarity Determinants

Filamentous fungi are defined by the ability to form highly polarized hyphae that invade and colonize substrates. Polarized hyphal growth requires the formation of a stable polarity axis that confines cell wall deposition to a discrete cortical site. Axis formation is presumably triggered by positional signals that locally regulate the organization of the cytoskeleton and vesicle trafficking machinery. Detailed microscopic analyses have identified several cellular systems that are intimately involved in hyphal morphogenesis, and complementary genetic studies emphasize the overall complexity of the underlying mechanisms. A major limitation to understanding these mechanisms is the complete lack of insight into the interactions between the proteins involved in hyphal morphogenesis. The generation of a genetic interaction network for polarity determinants would provide a robust framework for subsequent biochemical studies that reveal the molecular basis of hyphal morphogenesis. Ultimately, this should enable better manipulation of hyphal growth for human benefit.

Proposal in preparation in collaboration with Dr. Steve Harris and Dr. Meritxell Riquelme.

5) The Role of Protein Myristoylation in Morphogenesis

The role of protein lipidation in cell development remains ambiguous. One type of protein lipidation is N-terminal myristoylation, the addition of the fatty acid to the N-terminus of its target protein. The swoF developmental mutant in the model eukaryotic system Aspergillus nidulans has been found to disrupt the N-myristoyl transferase gene. This mutant is unable to maintain hyphal polarized growth during. To understand the connection between this developmental defect and protein myristoylation we have isolated and begun characterization of six suppressors of swoF. We have also used a prediction algorithm to infer that the A. nidulans proteome contains only 41 proteins that are predicted to be modified by myristoylation. The overall objective of this project is to characterize elements involved in both cell development and protein myristoylation in A. nidulans.

Key Course Learning Outcomes

1. You will define core concepts and terminology that will allow you to be conversant in modern Fungal Biology.

2. You will summarize specific examples of fungi as pathogens of humans, animals and plants.

3. You will explain the effect of specific fungal metabolites on the environment and society.

4. You will explain the ecological roles of fungi with specific examples of their interactions with other species.

5. You will assess current perceptions of toxic fungi in the media and the legal system.

6. You will collect information and produce a paper and a talk to be given to your peers in a fungal biology topic of your choice.

7. You will evaluate your peers’ level of understanding by assessing their presentations.

Spring 2008 Course Syllabus

PLPA625 Plant Pathogenic Fungi: This course is designed to introduce advanced students to the Kingdom Fungi. Topics include taxonomy, phylogenetics, and classification schemes used by mycologists and plant pathologists. In addition, the cell biology associated with fungal form and function will be explored along with investigation of cellular physiology, the cell cycle, cell signaling and fungus-plant interactions at the molecular level. The nature of the course requires reference to standard mycology textbooks to gain familiarity with the diversity of the fungal kingdom as well as reference to current literature dealing with all aspects of fungal biology. Although we intend to expose students to a wide array of topics, each topic will be covered to only a limited extent. Therefore, we intend to focus on the conceptual framework of modern research in mycology and fungal plant pathogenesis rather than a comprehensive exploration of mycology nomenclature and systematics.

Fall 2006 Course Syllabus