Abstract
Borbonol, a preformed antifungal substance, was isolated from roots and stems of
Persea borbonia and was detected in tissues of several other
Persea spp. showing varying degrees of resistance to
Phytophthora cinnamomi. However, it was not found in the highly susceptible species,
Persea indica. Borbonol was isolated as a mixture of four chemically related compounds, the major one of which (borbonol-2) was structurally identical to the previously described compound, isoobtusilactone A. Borbonol significantly inhibited vegetative growth of
Phytophthora cinnamomi at a minimum concentration of 1 μg ml
−1 and inhibited sporangium production at concentrations of 5 to 10 μg ml
−1. Despite its potent antifungal activity, the available evidence does not causally link it to expression of the resistance to
Phytophthora cinnamomi that occurs in several wild
Persea spp.