II. Requested Duration: October 2003 through September 2008

III. Title: Biochemistry and Genetics of Plant-Fungal Interactions

Filamentous fungal pathogens cause diseases on all agricultural crops around the world resulting in millions of tons of crop losses and billions of dollars in lost revenue annually. Strategies to combat fungal diseases include fungicides, crop rotation, plant resistance, and disease-free seed all of which have had limited success in controlling disease. The ability of fungi to develop fungicide resistance and overcome plant resistance continues to interfere with designing long term control measures for pathogenic fungi. For many decades, liberal fungicide application regimes was the main strategy for fungal disease control. However, in recent years, control of disease in agriculture has become challenging due to the removal and/or federal regulations concerning fungicides. With the loss of this traditional disease control measure, the need for new, innovative control measures that are economically sound, and environmentally friendly, become more important than ever to address future needs. Unfortunately, there is a dearth of knowledge concerning the biochemical and genetic bases of fungal pathogenicity which has hindered the development of alternative disease control strategies.

A better understanding of plant-fungal interactions and the response of plants to pathogens is critical to the development of effective and long term control measures. For example, phytopathogenic fungi express several different pathogenic lifestyles including biotrophy, hemibiotrophy, and necrotrophy, and may show tissue specificity or microhabitat preferences. Even within each of these lifestyles, pathogenesis may be correlated to toxins or extracellular enzymes. Clearly, pathogenesis is complex. In addition, the level of complexity surrounding pathogenesis studies is exacerbated by the fact that there are numerous species of plant pathogenic fungi of agricultural importance. In order to realistically make advances in understanding pathogenesis and hence, provide insightful information for the development of management tools, the multi-disciplinary complexities involved in host-pathogen interactions must be simultaneous studied with several fungal genera. If granted a renewal, the goal of the NCR-173 committee will be to design meetings in which individuals from several diverse disciplines and fungal systems will be able to interact and share information (via a website based platform) to better understand host-pathogen interactions.

Initiated in 1991 (first meeting - January 1992), and renewed in 1994 and 1998, the NCR-173 group began by focusing on the genetics and biochemistry of host-parasite interactions in the genus Colletotrichum. Colletotrichum was chosen because it is a model fungal system for the study of phytopathogenesis. Collectively, Colletotrichum species are easy to maintain and manipulate in culture, numerous research laboratories worldwide study this genus, and plant bio-assays, biochemical, molecular, and genetic protocols have been optimized in several of these species. By focusing our efforts on a single genus, an enormous amount of information was quickly obtained from the various labs. The exchange of ideas and results in subsequent meetings allowed us to begin building the foundation for understanding the basis of plant-fungal interactions. Through collaborative interactions made possible by this NCR committee, understanding the genetic and molecular bases of pathogenicity in the fungal genus Colletotrichum has been advanced (Appendix 1). Major areas of research have focused on classical genetic analysis, intercellular communication between fungal and plant cells, molecular systematics of this genus, chromosomal analysis, molecular transformation of these fungi, and genetic aspects of disease. In addition, over the last 3 years (since the previous renewal) several laboratories have made significant advances in these areas both collectively and individually. These developments have occurred, in large part, as a result of concerted interactions among the participants of NCR-173 both during and subsequent to our annual meetings. We have met annually and these sessions have fostered scientific information exchange and an opportunity to coordinate research efforts and management strategies into host-fungal interactions encompassing the genus Colletotrichum and more recently, has expanded to other fungal genera as well.

We have continually stressed interdisciplinary activities which are clearly reflected in the make up of our participants. Membership in NCR-173 includes classical geneticists, population biologists, evolutionary biologists, molecular biologists, physiologists, mycotoxicologists, plant molecular biologists, field epidemiologists, and pest management scientists. Thus, this is an exceptional collaborative interaction between a blend of basic and applied scientists representing land grant universities, private industry and government. We also have committee members from throughout the region, the country, and other countries. The interdisciplinary nature of the NCR-173 meetings has allowed several laboratories to make greater advances than if the group were restricted to specific labs or systems. Over time we have found that the inclusion of scientists studying pathogenesis in other fungal systems has been of tremendous value. As a result of this increasing scientific diversity in our membership and as noted in our previous administrative review, we are proposing a change to the title of our group to more accurately reflect the extended focus of our committee. The change in title of NCR-173 will reflect the shift in emphasis from Colletotrichum to now include several different pathogenic fungal genera such as Alternaria, Fusarium, Sclerotinia, Cochliobolus, Pyrenophera, Monolinia, and Ustilago.

These fungi were chosen because they represent diverse genera in which major areas of research from labs worldwide are focused. Collectively, these fungi express several different pathogenic lifestyles (biotrophy, hemibiotrophy, and necrotrophy), may show tissue specificity or microhabitat preferences, and produce toxins and/or extracellular enzymes involved in pathogenicity. In addition, classical genetic analysis, biochemical, molecular, and applied field studies addressing plant-fungal interactions are presently being addressed in these systems. By widening our scope from a single model system to encompass several model systems, the information shared will allow us to compile and analyze a great deal of information regarding the universal similarities and unique differences involved in pathogenesis. In so doing, NCR-173 will broaden its scope and generate new synergisms.

This is a request for a continuation of an existing NCR committee. During the tenure of the existing committee, we have had five very successful and productive meetings, three of which included international participation. As stated, our repository is in place; over 1000 cultures are present. A WEB homepage has also been developed and can be accessed (http://www.uark.edu/depts/plant/). The homepage provides general information about the repository and allows individuals to view or download the database. Scientists can request a culture online or provide needed information to deposit a culture into the repository. Culture requests still must meet all state and federal requirements prior to shipping. Committee members have published numerous papers since 1998 that are directly relevant to our objectives and research efforts. Several of those manuscripts have been the result of collaborations established and maintained because of NCR-173 (Appendix 1).

There will be two officers for NCR-173. A secretary will be elected every two years at the appropriate annual meeting. The secretary records and distributes minutes of the annual meeting, and then becomes chair of the committee for the following two years. The chair directs the activities of the committee, serves as the liaison between the committee and the administrative advisor, and makes arrangements for the next annual meeting.

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Admin. Advisor, NCA-14 Chair, NCA-14