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Title: THE POTENTIAL FOR INCREASING PHYTOALEXINS TO ENHANCE PLANT RESISTANCE TO OOMYCETE PATHOGENS

Author
item ZHU, YUN - HARC
item AGBAYANI, RICELLE - HARC
item SAVORY, ELIZABETH - UNIV HAWAII, HONOLULU
item MIYASAKA, SUSAN - UNIV HAWAII, HONOLULU
item Fitch, Maureen
item Moore, Paul

Submitted to: International Congress of Biochemistry and Molecular Biology
Publication Type: Abstract Only
Publication Acceptance Date: 2/3/2006
Publication Date: 6/18/2006
Citation: Zhu, Y.J., Agbayani, R., Savory, E., Miyasaka, S., Fitch, M.M., Moore, P.H. 2006. The Potential for Increasing Phytoalexins to Enhance Plant Resistance to Oomycete Pathogens. The 20th International Congress of Biochemistry and Molecular Biology. Kyoto, Japan. June 18-23, 2006.

Interpretive Summary:

Technical Abstract: Phytoalexins have been shown to be important natural components in plant defense against pathogens. Although the tropical fruit crop papaya (Carica papaya L.) produces several classes of phytoalexins that have been shown to have anti-microbial activity, it is nevertheless highly susceptible to fungal and oomycete pathogens. Resveratrol (trans-3,4’, 5-trihydroxy-stilbene), produced in grapevine and peanut, has been reported to have good anti-microbial activity against several plant pathogens. Therefore, we used an in-vitro inhibition assay to evaluate the effect of resveratrol against Phytophthora, Colletotrichum, and Pythium, that are common pathogens of papaya and taro (Colocasia esculenta). Resveratrol had no effect on the papaya fruit rot pathogen anthracnose, Colletotrichum gloeosporiodes. Nor was it effective on the taro root rot pathogen Pythium. However, it had a significant inhibitory effect at concentrations between 100'M and 1.0 mM on the growth of Phytophtohora mycelia. Media containing 1.0 mM resveratrol inhibited growth of P. palmivora by 50% and of P. colocasiae by 82%. We then transformed papaya with the grapevine stilbene synthase gene and found increased production of resveratrol that correlated with increased resistance to P. palmivora. Similar approaches being used to increase resistance of taro against P. colocasiea will be presented. The potential for increasing phytoalexins to enhance plant resistance to oomycete pathogens will be discussed.