Authors: Yun J Zhu Ricelle Agbayani Mel C Jackson C S Tang Paul H Moore
Publish Date: 2004/08/12
Volume: 220, Issue: 2, Pages: 241-250
Abstract
The phytoalexin resveratrol trans354′trihydroxystilbene a natural component of resistance to fungal diseases in many plants is synthesized by the enzyme trihydroxystilbene synthase stilbene synthase EC 23195 which appears to be deficient or lacking in susceptible plants Earlier workers isolated a stilbene synthase gene Vst1 from grapevine Vitis vinifera L which has subsequently been introduced as a transgene into a range of species to increase resistance of hosts to pathogens to which they were originally susceptible Papaya Carica papaya L is susceptible to a variety of fungal diseases including root stem and fruit rot caused by the pathogen Phytophthora palmivora Since resveratrol at 10 mM inhibited mycelium growth of P palmivora in vitro we hypothesized that papaya resistance to this pathogen might be increased by transformation with the grapevine stilbene synthase construct pVst1 containing the Vst1 gene and its pathogeninducible promoter Multiple transformed lines were produced clonally propagated and evaluated with a leaf disk bioassay and whole plant response to inoculation with P palmivora RNA transcripts of stilbene synthase and resveratrol glycoside were induced in plant lines transformed with the grapevine pVst1 construct shortly after pathogen inoculation and the transformed papaya lines exhibited increased resistance to P palmivora The immature transformed plants appear normal and will be advanced to field trials to evaluate their utilityWe thank Dr R Hain from Bayer AG for providing the grapevine stilbene synthase construct Dr M Fitch ARS/USDA for advice on papaya transformation and clonal propagation and Dr S Schenck Hawaii Agriculture Research Center for providing fungal cultures and advice on pathogen studies This work was partially supported by a cooperative agreement No CA 5853203460 between the US Department of Agriculture Agricultural Research Service and the Hawaii Agriculture Research Center and by a special USDA ARS grant to the College of Tropical Agriculture and Human Resources of the University of Hawaii for minor crop pest control
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