Poster: Plant Pathogen/Symbiont Interactions

Abs # 762: Transgenic poplars expressing an antimicrobial cecropin-melittin chimeric gene

Presenter:	Yevtushenko, Dmytro P., dmytro@uvic.ca
Authors	Yevtushenko, Dmytro P. (A) (B)  Romero, Rafael  (A)   Kay, William W. (A) (B)  Misra, Santosh  (A) (B)
Affiliations:	(A): University of Victoria, Department of Biochemistry and Microbiology (B): SynGene Biotek Inc.

Few poplar species combine desirable growth characteristics with necessary disease resistance. Cationic antimicrobial peptides (CAP) present an effective natural defense system against a broad spectrum of pathogens and provide an opportunity to overcome the limitations of conventional breeding by expression of CAP genes in transgenic plants. Although poplar is a model system for tree biotechnology, many commercially valuable genotypes are difficult to transform and regenerate from tissue culture. We optimized an Agrobacterium-mediated transformation procedure for a hybrid poplar (Populus nigra x P.maximowiczii) using the b-glucuronidase (GUS) reporter gene system. A plant transformation vector expressing a modified cecropin-melittin chimeric gene, which encodes a small membrane-active peptide with antimicrobial and antifungal properties, was introduced into poplar plants. Development of an efficient petiole- and leaf-based regeneration protocol and explant-dependent selection conditions were crucial to generate transgenic poplars. Stable gene integration in regenerated plants was confirmed by PCR. Bioassay of transgenic plants using co-cultivation of leaf explants in the presence of Fusarium ssp. showed enhanced plant resistance to the pathogenic fungus. These plants are being tested against poplar leaf rust caused by a Melampspora species, and against other phytopathogens.