USE OF VOLATILE METABOLITE PROFILES TO DISCRIMINATE FUNGAL DISEASES OF CORTLAND AND EMPIRE APPLES

A. Vikram, B. Prithiviraj, A.C. Kushalappa

Abstract


The volatile metabolites from the headspace gas of apple fruits, cvs Cortland and Empire, inoculated with water or four different fungi, Botrytis cinerea Pers., Penicillium expansum Link, Mucor piriformis Fischer and Monilinia sp, were profiled using gas chromatography/ mass spectrometry (GC/MS). A total of 1081 different peaks were detected. The number of compounds that occurred in abundance ³105 and relatively consistently in 6 replicates over 3 incubation periods was 34 and 36, in Cortland and Empire, respectively. Of the consistent metabolites in Cortland, 19 were specific to one or more diseases/inoculations, including five that were unique to apples inoculated with different pathogens. In Empire, 15 compounds were specific to one or more diseases/inoculations, including 3 that were unique to single pathogens. In Cortland, dimethyl ether and propanal were specific to Penicillium, while acetic acid methyl ester and styrene were common only to B. cinerea and Monilinia. Similarly, in Empire the compounds 3,4-dimethyl-1-hexene, butanoic acid-2-methylpentyl ester, and 2-methyl propyl hexanoate were common only to B. cinerea, M. piriformis and Monilinia, respectively. A factor analysis, considering 29 relatively consistent metabolites for both cultivars, discriminated all the disease/inoculations. The disease/ inoculation discriminatory metabolites or groups of these metabolites based on factor models could be used for the early detection of apple diseases in storage. However, for commercial application of the system scale-up studies and validation under practical condition is required.

Keywords


disease diagnosis; post-harvest pathogens; metabolomics; electronic nose

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DOI: http://dx.doi.org/10.4454/jpp.v86i3.991

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