In vitro tolerance to Botrytis cinerea of grapevine 41B rootstock in transgenic plants expressing the stilbene synthase Vst1 gene under the control of a pathogen-inducible PR 10 promoter

Resveratrol is a major phytoalexin in grapevine but its synthesis in respon se to phytopathogen attack decreases with grape berry ripening, A chimeric gene combining an alfalfa PR 10 promoter and Vst1 (Vitis stilbene synthase 1) gene was introduced into the genome of 41B rootstock, Transgenic plants were analysed for resveratrol production in leaves infected with Botrytis u sing an in vitro test. Among the 50 transgenic lines analysed, some exhibit ed a production lower than the non-transgenic control, but others accumulat ed resveratrol from 5-100-fold, Moreover, in the latter clones, symptoms we re highly reduced in response to infection, These results were a good indic ation that the combination of a pathogen-inducible promoter and a defence g ene may increase tolerance against fungi in grapevine, The efficacy of this approach should be further tested by experiments conducted in the vineyard .