Margaret E. Daub

Professor Plant Pathology

Head, Department of Plant Biology

• B.A. (Biology), College of Wooster, Ohio;
• Ph.D. (Plant Pathology), U. of Wisconsin-Madison

Research Interests

Efforts in my laboratory are focused on the isolation and characterization of genes from plant pathogens that have potential usefulness in the genetic engineering of disease-resistant plants. Our major efforts currently are directed at developing strategies for engineering resistance to a group of fungal plant pathogens (Cercospora species) which parasitize plants by producing photoactivated, active-oxygen-producing toxins. Genes that encode resistance have been isolated from the fungus and are being characterized for function and for their ability to impart resistance. One of the resistance genes encodes a key step in a novel pathway for biosynthesis of pyridoxine (vitamin B6). This pathway is distinct from the defined pathway in E. coli, however, plants, fungi, protozoa, Archaebacteria, and some eubacteria share this new pathway. We are currently working to isolate and characterize other steps in this pathway. In addition, we are studying the role of pyridoxine in active oxygen resistance, as we have shown that pyridoxine is a potent quencher of singlet oxygen and appears to play a heretofore unrecognized role in cellular antioxidant defenses. Efforts are also ongoing in the lab to isolate and characterize toxin degradation genes from bacteria, as toxin degradation may also be a useful strategy for obtaining disease resistance.

Molecular Plant-Pathogen Interactions

Publications (Last 5 years)

• Ehrenshaft, M., Jenns, A. E., and Daub, M. E. 1995. Targeted gene disruption of carotenoid biosynthesis in Cercospora nicotianae reveals no role for carotenoids in photosensitizer resistance. Mol. Plant Microbe Interact. 8:569-575.
• Clark, R. A., Stephens, T. R., Bowden, E. F., and Daub, M. E. 1995. Electrochemical studies of the phytotoxin cercosporin. J. Electroanal. Chem. 389:205-208.
• Jenns, A. E., Scott, D. L., Bowden, E. F., and Daub, M. E. 1995. Isolation of mutants of the fungus Cercospora nicotianae altered in their response to singlet-oxygen-generating photosensitizers. Photochem. Photobiol. 61:488-493.
• Jenns, A. E. and Daub, M. E. 1995. Characterization of mutants of Cercospora nicotianae sensitive to the toxin cercosporin. Phytopathology 85:906-912.
• Moyer, J. W., Daub, M. E., and Robb, K. L. 1995. Thrips and TSWV/INSV. pp. 119-131 In W. Banner and M. Klopmeyer, eds. New Guinea Impatiens, A Ball Guide. Ball Publishing, Batavia, IL.
• Daub, M. E., Jenns, A. E., and Ehrenshaft, M. 1995. Fungal resistance to photosensitizers that generate singlet oxygen. pp. 201-216 In J. R. Heitz and K. R. Downum, eds. Light-Activated Pest Control. American Chemical Society Press, Washington, DC.
• Sherman, J. M., Moyer, J. W., and Daub, M. E. 1996. Genetically engineered resistance to tomato spotted wilt virus in chrysanthemum (Dendranthema grandiflora): a model system for virus protection in ornamental crops. Acta Hort. 431:432-441.
• Daughtrey, M., Jones, R., Baker, J., Moyer, J., and Daub, M. 1997. Tospoviruses strike the greenhouse industry: INSV has become a major pathogen on flower crops. Plant Disease 81:1220-1230.
• Daub, M. E., and Ehrenshaft, M. 1997. The photoactivated toxin cercosporin: toxicity, resistance, regulation and role in disease. pp. 37-66 In R. K. Upadhyay and K. G. Mukerji, eds. Toxins in Plant Disease Development and Evolving Biotechnology. Oxford & IBH Publishing, Co. PVT. LTD. New Delhi.
• Daub, M. E., Jones, R. K., and Moyer, J. W. 1997. Biotechnological approaches for virus resistance in floral crops. pp. 335-351 In R. L. Geneve, R. N. Trigiano, J. E. Preece, and S. A. Merle, eds. Biotechnology of Ornamental Plants. CAB International, Wallingford.
• Sherman, J. M, Moyer, J. W., and Daub, M. E. 1998. A single high-efficiency regeneration and Agrobacterium-mediated transformation system for the genetic engineering of multiple chrysanthemum genotypes. J. Am. Soc. Hort. Sci. 123:189-194
• Sherman, J. M., Moyer, J. W., and Daub, M. E. 1998. Tomato spotted wilt virus resistance in chrysanthemum expressing the virual nucleocapsid gene. Plant Dis. 82 :407-414.
• Ehrenshaft, M., Jenns, A. E., Chung, K. R., and Daub, M. E. 1998. SOR1, a gene required for photosensitizer and singlet oxygen resistance in Cercospora fungi is highly conserved in divergent organisms. Mol. Cell 1:603-609.
• Daub, M. E., Ehrenshaft, M., Jenns, A. E., and Chung, K. R. 1998. Active oxygen in fungal pathogenesis of plants: the role of cercosporin in Cercospora diseases. pp. 31-56 In J. T. Romeo, K. R. Downum, and R. Verpoorte, eds. Phytochemical Signals and Plant-Microbe Interactions, Recent Advances in Phytochemistry, Vol 32, Plenum Press, NY.
• Moyer, J. W., and Daub, M. E. 1998. Control TSWV/INSV in floral crop production: gene transfer technology may offer solutions. SAF Grower Notes 3:5-7
• Ehrenshaft, M. Chung, K. R., Jenns, A. E., and Daub, M. E. 1999. Functional characterization of SOR1, a gene required for resistance to photosensitizing toxins in the fungus Cercospora nicotianae. Current Genetics 34:478-485.
• Chung, K. R., Jenns, A. E., Ehrenshaft, M., and Daub, M. E. 1999. A novel gene required for cercosporin toxin resistance in the fungus Cercospora nicotianae. Mol. Gen. Genet. 262:382-389.
• Ehrenshaft, M., Bilski, P., Li, M., Chignell, C. F., and Daub, M. E. 1999. A highly conserved sequence is a novel gene involved in de novo vitamin B6 synthesis. Proc. Natl. Acad. Sci. 96:9374-9378.
• Herrero, S., Culbreath, A. K., Csinos, A. S., Pappu, H. R., Rufty, R. C., and Daub, M. E. 2000. Nucleocapsid gene-mediated transgenic resistance provides protection against tomato spotted wilt virus epidemics in the field. Phytopathology 90:139-147.
• Daub, M. E., Li, M., Bilski, P., and Chignell, C. F. 2000. Dihydrocercosporin singlet oxygen production and subcellular localization: a possible defense against cercosporin phototoxicity in Cercospora. Photochem. Photobiol. 71:135-140.
• Bilski, P., Li, M. Y., Ehrenshaft, M., Daub, M. E., and Chignell, C. F. 2000. Vitamin B6 (pyridoxine) and its derivatives are efficient singlet oxygen quenchers and potential fungal antioxidants. Photochem. Photobiol. 71:129-134.
• Daub, M. E. and Ehrenshaft, M. 2000. The photoactivated Cercospora toxin cercosporin: contributions to plant disease and fundamental biology. Annu. Rev. Phytopathol. 38 (In Press).

Contact Information

Dr. Margaret E. Daub
North Carolina State University
Department of Plant Biology
Box 7612
Gardner Hall 2124
Raleigh, NC 27695-7612
Tel: (919) 513-3807
FAX: (919) 515-3436
Email: Margaret_Daub@ncsu.edu