Poster: Late and Moved Abstracts

Abs # 950: Broad- spectrum activity of an amphibian cationic peptide against plant pathogens

Presenter:	Misra, Santosh , smisra@uvic.ca
Authors	Osusky, Milan  (A)   Osuska, Lubica  (A)   Kay, William W (A)   Misra, Santosh  (A)
Affiliations:	(A): University of Victoria

Dermaseptin B1 is very potent cationic antimicrobial peptide found in the skin secretions of the arboreal frog Phyllomedusa bicolor. The synthetic peptide MsrA2 (with an additional methionin at its N-terminus) showed strong in vitro antimicrobial activities against many phytopathogenic bacteria and fungi. MsrA2 was expressed under the control of duplicated-enhancer CaMV 35S promoter in the potato (Solanum tuberosum L.) cultivar Desiree. The stable incorporation of msrA2 gene into plant genome was confirmed by PCR and expression by RT-PCR. The transgenic potato plants showed strong resistance to Erwinia carotovora, the cause of the soft rot of potato tubers. However, the most devastating diseases of potatoes are caused by fungi - late blight disease caused by Phytophthora infestans, and pink rot disease caused by Phytophthora erythroseptica. The diseases are effectively controlled by multiple applications of fungicides. Unfortunately, resistance to fungicides available for these diseases, has developed in both species. Highly stringent challenges demonstrated powerful resistance of transgenic potatoes expressing MsrA2 to several fungal phytopathogens including P. infestans and P. erythroseptica. The morphology and yield of transgenic Desiree plants and tubers were unaffected. Because of its broad-spectrum of antimicrobial activities, MsrA2 can be used to increase plant resistance against microbial infections in other crops (wheat, barley, corn, sugar beet), trees, and flowers threatened by many different bacterial and fungal phytopathogens.. This research is supported by the National Centres of Excellence, Canadian Bacterial Diseases Network funding to SM.