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Tomato Plants Transformed with the Inhibitor-of-Virus-Replication Gene Are Partially Resistant to Botrytis cinerea

First, second, third, fourth, and seventh authors: Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250; fifth author: Evogene Ltd. P.O.B. 2100, Rehovot 76121; and sixth author: The Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.

Tomato plants transformed with a cDNA clone encoding the inhibitor-of-virus-replication (IVR) gene were partially resistant to Botrytis cinerea. This resistance was observed as a significant reduction in the size of lesions induced by the fungus in transgenic plants compared with the lesions on the nontransgenic control plants. This resistance was weakened when plants were kept at an elevated temperature, 32°C, before inoculation with B. cinerea compared with plants kept at 17 to 22°C prior to inoculation. Resistance correlated with the presence of IVR transcripts, as detected by reverse transcription-polymerase chain reaction. This is one of the few cases in which a gene associated with resistance to a virus also seems to be involved in resistance to a fungal disease.