Discrimination of three fungal diseases of potato tubers based on volatile metabolic profiles developed using GC/MS

Summary Volatiles from the headspace of Russet Burbank potato tubers, non-wounded non-inoculated (N-control), wounded-inoculated-with sterile water (W-control), wounded-inoculated withPhytophthora infestans, Pythium ultimum orBotrytis cinerea, respectively, were sampled at 3 and 6 days after inoculation (dai), using gas chromatography/mass spectrometry (GC/MS).Botrytis inoculated tubers produced two specific volatiles: 2-2-propenyl-l,3-dioxolane and 3, 5-heptadiyn-2-one, while thePythium inoculated tubers produced three: 2-methyl-l-butanol, 2-butanone and 2-methyl-2-butanamine. Similarly, ethoxy-ethene was specific forPhytophthora inoculated tubers. 5-l-methylethylidene-l,3-cyclopentadiene was specific to W-control tubers. Discriminant analysis models based on metabolic fingerprints of metabolites or of mass ions correctly classified 80 to 100% of the observations into respective inoculations/diseases. However, a test-validation correctly classified only 44, 50, 44, 50 and 44% of the fingerprints based on consistent metabolites and 44, 63, 38, 75 and 31% of fingerprints based on mass ions, intoBotrytis, N-control,Phytophthora, Pythium and W-control, respectively. The disease discriminatory metabolite markers and the discriminant models developed here can be used to differentiate the three diseases of Russet Burbank potato tubers, after further validation under commercial conditions.