In the course of study on the roles of phytotoxins in the pathogenicity of Botrytis cinerea, we isolated two novel
phytotoxins. They were identified as 3-O-acetyl botcinol and 3-O-acetyl botcinolide. In this study, we investigated
correlation between the two phytotoxins and the pathogenicity of B. cinerea. In liquid cultures, the two
phytotoxins were not produced by three low pathogenic isolates out of 25 B. cinerea isolates. Among strong or
moderate pathogenic isolates, some produced the two phytotoxins, but the others did not. On the other hand,
the ethyl acetate extracts of fermentation broths of 10 out of 25 isolates showed phytotoxic activity against
various plants tested in a whole plant assay. The phytotoxins were detected in all of the 10 phytotoxic ethyl
acetate extracts. In planta, the two phytotoxins were detected in all of the plant tissues infected with strong
pathogenic isolates. However, there was no correlation between the ability of B. cinerea isolates to produce the
two phytotoxins and their pathogenicities. The two phytotoxins began to detect in tomato plant tissues
infected with B. cinerea 2-16 at 3 days after inoculation, increased gradually till 4 days after inoculation, and
then decreased. The above results suggest that 3-O-acetyl botcinol and 3-O-acetyl botcinolide are one of
pathogenicity factors for B. cinerea, but not a primary determinant of its pathogenicity.