Duration: 10/01/2003 to 09/30/2008

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

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 (Farr et al., 1989; Knogge, 1996; Sutton, 1980).

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 (Bailey et al., 1992; Redman et al., 2001). Even within each of these lifestyles, pathogenesis may be correlated to toxins or extracellular enzymes (Anderson, 1978; Centis et al., 1996; English et al., 1972). Clearly, pathogenesis is complex (Dangl et al., 1996; Mendgen et al., 1995; Kuc, 1990; Hammond-Kosack and Jones, 1996). 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 (Prusky et al., 2000). 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 (Freeman and Rodriguez, 1992; Hammerschmidt and Kuc 1982a; Hammerschmidt et al., 1982b). 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 (Freeman and Rodriguez, 1993; Hwang et al., 1995; Kolattakudy et al., 1995; Kubo et al., 1996; Redman et al, 1999; Rodriguez and Redman, 1992). 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.

Objectives

Procedures and Activities

Expected Outcomes and Impacts

Projected Participation

View Appendix E: Participation

Educational Plan

This information exchange group, which was established in 1991, has an excellent track record of exchange of research and educational information through the workshop format of its annual meetings and its website ( www.uark.edu/depts/plant ). The website allows easy, inexpensive access of information to all members pertaining to the exchange of ideas, coordination of laboratory and field research, protocols, contacts, meeting highlights, schedules, publications and the fungal repository. Emphasis will be placed on publication of both individual and joint research/review articles and enhancing the available information base allowing for the better understanding of plant-fungal interactions. Ultimately, this information will be used to provide guidance for the development of management tools to enhance economic productivity and promote environmental stewardship.

Organization/Governance

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.

Literature Cited

REFERENCES

1. Anderson, A.J. 1978. Extracellular enzymes produced by Colletotrichum lindemuthianum and Helminthosporium maydis during growth on isolated bean and corn walls. Phytopath. 68:1585-1589.

2. Bailey, J.A., O'Connell, R.J., Pring, R.J. and Nash, C. 1992. Infection strategies of Colletotrichum species. in Colletotrichum: Biology, Pathology and Control. J.A. Bailey and M.J. Jeger eds. CAB International, UK. pp88-120.

3. Centis, S., Dumas, B., Fournier, J., Marolda, M. and Esquerre-Tugaye, M.T. 1996. Isolation and sequence analysis of Clpg1, a gene coding for an endopolygalacturonase of the phytopathogenic fungus Colletotrichum lindemuthianum. Gene. 170:125-129.

4. Dangl, J.L., Dietrich, R.A., and Richberg, M.H. 1996. Death dont have no mercy: cell death programs in plant-microbe interactions. Plant Cell. 8:1793-1807.

5. English, P.D., Maglothin, A., Keegstra, K. and P. Albersheim. 1972. A cell wall-degrading endopolygalacturonase secreted by Colletotrichum lindemuthianum. Plant Physiol. 49:293-297.

6. Farr, D.F., Bills, G.F., Chamuris, G.P., & Rossman, A.Y. 1989. Fungi on plants and plant products in the United states. APS Press, St. Paul, Minnesota, USA.

7. Freeman, S. and Rodriguez, R.J. 1993. Genetic conversion of a fungal plant pathogen to a non-pathogenic endophytic mutualist. Science. 260:75-78.

8. Freeman, S. and Rodriguez, R.J. 1992. A rapid, reliable bioassay for pathogenicity of Colletotrichum magna on cucurbits and the isolation of non-pathogenic mutants. Plant Disease. 76:901-905.

9. Mendgen, K., Mitchell, A.J., Callow, J.A., and OConnell, R.J. 1995. Analysis of differentiation and development of the specialized infection structures formed by biotrophic fungal plant pathogens using monoclonal antibodies. Can. J. Bot. 73(suppl. 1):s408-s417.

10. Hammerschmidt, R. and Kuc, J. 1982a. Lignification as a mechanism for induced systemic resistance in cucumber. Physiol. Plant Pathol. 20:61-71.

11. Hammerschmidt, R., Nuckles, E. M., and Kuc, J. 1982b. Association of enhanced peroxidase activity with induced systemic resistance of cucumber to Colletotrichum lagenarium. Physiol. Plant Pathol. 20:73-82.

12. Hammond-Kosack, K.E. and Jones, J.D.G. 1996. Resistance gene-dependent plant defense responses. Plant Cell. 8:1773-1791.

13. Hwang, CS., Flaishman, M.A., and Kolattukudy, P. 1995. Cloning of a gene expressed during appressorium formation by Colletotrichum gloeosporioides and a marked decrease in virulence by disruption of this gene. Plant Cell. 7:183-193

14. Knogge, W. 1996. Fungal infection of plants. Plant Cell. 8:1711-1722.

15. Kolattukudy, P.E., Rogers, L.M., Li, D., Hwang, CS., and Flaishman, M.A. 1995. Surface singnaling in pathogenesis. Proc. Natl. Acad. Sci. 92:4080-4087.

16. Kubo, Y., Takano, Y., Endo, N., Yasuda, N., Tajima, S., and Furusawa, I. 1996. Cloning and structural analysis of the melanin biosynthesis gene SCD1 encoding s-cytalone Dehydratase in Colletotrichum lagenarium. Appl. Environ. Micro. 62:4340-4344.

17. Kuc, J. 1990. A case for self defense in plants against disease. Phytoparasitica 18:3-8.

18. Prusky, D., Freeman, S., and Dickman, M., eds. 2001. in Host specificity, pathology and host pathogen interactions of Colletotrichum. APS press,

19. Redman, R.S., Dunnigan. D.D., and Rodriguez, R.J. 2001. Fungal symbiosis from mutalism to parasitism: who controls the outcome, host or invader? New Phytol. 151:705-716.

20. Redman, R.S., Ranson, J.C., and Rodriguez, R.J. 1999. Conversin of a pathogenic fungus Colletotrichum magna to a nonpathogenic endophytic mutualist by gene disruption. MPMI. 11:969-975.

21. Rodriguez, R.J. and R. Redman. 1992. Molecular transformation and genome dynamics of Colletotrichum species. in The Biology of Colletotrichum Species. John Bailey, Richard Shattock eds., Cambridge press, England. pp47-66.

22. Sutton B. C. 1980. The coelomycetes, pp524-537. Commonwealth Mycoligical Institute, England

Attachments

Land Grant Participating States/Institutions

AR, FL, GA, IN, KS, KY, MI, MN, MS, NC, NY, OR, SC, TX, WI

Non Land Grant Participating States/Institutions

CSIRO Tropical Agriculture Group, Hebrew University, Noble Foundation, University of British Columbia, University of Kyoto, University of Washington, Volcani Institute