Induction of stilbene synthase by Botrytis cinerea in cultured grapevine cells

The interaction between Botrytis cinerea Pers. and grapevine (Vitis vinifera L.) was studied in a model system of reduced complexity. Cultured plant cells and fragments of fungal cell wall were used to simulate some of the processes taking place upon infection of grapevine with B. cinerea. A soluble glucan elicitor was prepared from the fungal cell wall by acid hydrolysis. Like the insoluble wall preparation, the soluble fragment derived from the cell wall acted upon plant cells in eliciting stilbene formation. In grapevine cells, the interaction with the fungus led to a dramatic shut-off general protein synthesis and to the selective formation of a small set of proteins involved in induced resistance. The proteins synthesized de novo with highest rates were stilbene synthase (StiSy) and l-phenylalanine ammonia-lyase (PAL). Stilbene synthase was purified to apparent homogeneity and its molecular properties were characterized. The enzyme is a homodimer with subunit M_r 43 000 and pl = 5.4. Although there were indications of the presence of isoenzymes, these were not distinguished by charge differences. In size, the grapevine StiSy shows microheterogeneity and differs from the appreciably larger enzyme prepared from peanut. Prior to induction by fungal attack, virtually no stilbenes are formed in the plant cell. Upon induction of the pathway leading to the stilbene resveratrol, StiSy activity determines the ratelimiting step in the metabolic sequence. The highly induced grapevine cells produce and secrete resveratrol and derivatives which are known to be fungistatic.Abbreviations PAL l-phenylalanine ammonia-lyase - SDS-PAGE sodium dodecyl sulfate-polyacrylamine gel electrophoresis - StiSy stilbene synthase (resveratrol forming) The authors thank Dr. Blaich, Bundesforschungsanstalt Geilweilerhof, Siebeldingen, F.R.G., for provision of callus culture. This paper is based on research supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.     

Evaluation of potato tuber moth (Lepidoptera: Gelechiidae) resistance in tubers of Bt-cry5 transgenic potato lines

The potato tuber moth, Phthorimaea operculella (Zeller), in tropical and subtropical countries, is the most destructive pest of potato, Solanum tuberosum L. The larvae attack foliage and tubers in the field and in storage. The purpose of this study was to evaluate the efficacy of a Bt-cry5 transgene to control the potato tuber moth in tuber tissues. Tuber bioassays using stored (11-12 mo old) and newly harvested tubers of Bt-cry5-Lemhi Russet and Bt-cry5-Atlantic potato lines showed up to 100% mortality of 1st instars. Mortality was lowest in the newly harvested tubers of Bt-cry5-Atlantic lines (47.1-67.6%). Potato tuber moth mortality was 100% in the Bt-cry5-Spunta lines that were transformed with Bt-cry5 gene controlled by the CaMV 35S promoter (pBIML5 vector) and in 2 of 3 lines transformed with Bt-cry5 gene controlled by the Gelvin super promoter (pBIML1 vector). The transgenic Spunta lines expressing Bt-cry5 controlled by the patatin promoter (pBMIL2 vector) showed the lowest tuber moth mortality (25.6 and 31.1%). The Bt-cry5 transgenic lines with high tuber expression of B. thuringiensis have value in an integrated pest management system to control potato tuber moth.