Changes in diterpene resin profile of Austrocedrus chilensis following Phytophthora austrocedri infection

OLATE V.; VÉLEZ M.L.; GRESLEBIN A.G.; SCHMEDA-HIRSCHMANN G.

MOLECULES

MOLECULAR DIVERSITY PRESERVATION INTERNATIONAL-MDPI

Lugar: Basel; Año: 2015 vol. 20 p. 15084 - 15097

1420-3049

The populations of the Andean Cupressaceae Austrocedrus chilensis have beenseverely affected by a disease caused by the phytopathogenic fungus Phytophthora austrocedri.A study was undertaken to disclose changes in the resin composition of P. austrocedri-infectedindividuals, including naturally infected and artificially inoculated trees, compared withhealthy A. chilensis trees. GC-MS and 1H-NMR studies showed a clear differentiation amonghealthy and infected resins, with the diterpene isopimara-8(9),15-dien-19-ol as a relevantconstituent in resins from infected trees. The effect of resin fractions from P. austrocedriinfected trees on the pathogen was assessed by measuring the mycelial growth in agar plates.The most active fractions from resin obtained from infected trees inhibited fungal growth bynearly 50% at 1 mg/dish (35.37 μg/cm2). The main constituent in the active fractions were18-hydroxymanool and the aldehyde torulosal. Both compounds are oxidation products ofmanool and can be a chemical response of the tree to the pathogen or be formed from thepathogen as a biotransformation product of manool by microbial oxidation. While the diterpeneprofiles from A. chilensis tree resins can easily differentiate healthy and P. austrocedriinfected individuals, the possible conversion of manool to the antifungal derivatives 4 and 6by the microorganism remains to be established.