Volatile metabolic profiling for discrimination of potato tubers inoculated with dry and soft rot pathogens

Volatile metabolites from ‘Russet Burbank’ potatoes inoculated withErwinia carotovora ssp.carotovora (ECC),Erwinia carotovora ssp.atroseptica (ECA), andFusarium sambucinum (FSA) were analyzed by sampling the headspace at 3 and 6 days after inoculation and then using a gas chromatograph/mass spectrometer (GC/MS) to identify the compounds. Non-wounded noninoculated and wounded non-inoculated tubers served as checks. Compounds with an abundance of ≥105 and with frequency of ≥3 out of 20 replicates (10 replicates × 2 incubation times) were subjected to further analysis. A total of 81 volatile metabolites were detected, of which 58 were specific to one or common to a few, but not to all inoculations/diseases. Acetic acid ethenyl ester was unique to ECA, while cyclohexene, diazene, and methoxy-(1,1-dimethyl-2-dihydroxy-ethyl)-amine were unique to ECC, and 2,5-norbornadiene and styrene were unique to FSA. Several metabolites were common only to tubers inoculated with ECC and ECA and were not detected in fungus-inoculated or in control tubers. High abundances of acetone and butane were detected in ECC- and ECA-inoculated tubers, respectively. The possible use of differences in volatile metabolic profiles to discriminate diseases of potato tubers in storage is discussed.ResumenLos metabolites volátiles de la papa Russet Burbank, inoculados conErwinia carotovora ssp.carotovora (ECC),Erwinia carotovora ssp.atroseptica (ECA)y Fusarium sambucinum (FSA) se analizaron por muestreo del espacio circundante 3 y 6 días después de la inoculación. Para identificar los compuestos se utilizó un cromatógrafo de gas/ espectómetro de masa (GC/MS). Sirvieron como testigos, tubérculos sin herir sin inocular y tubérculos heridos sin inocular. Los compuestos en cantidades ≥105 y con una frecuencia ≥3 de 20 repeticiones (10 repeticiones × 2 periodos de incubación), fueron sujetos a análisis posteriores. Se detectó un total de 81 metabolites volátiles, de los cuales 58 fueron especificos a una o comunes a unas pocas pero no a todas las inoculaciones/enfermedades. El ácido acético etenil ester fue exclusivo de ECA, mientras que el ciclohexeno, diazeno y metoxi-(1,1 dimetil-2-dihidroxi-etil)-amina fueron exclusivos de ECC, y el 2,5-norbordarieno y el estireno fueron exclusivos de FSA. Algunos metabolites fueron comunes solamente en los tubérculos inoculados con ECC y ECA y no se detectaron en los inoculados con el hongo o en los testigos. Abundante acetona y butano se detectó en los tubérculos inoculados con ECC y ECA respectivamente. Se discute el posible uso de las diferencias de los perfiles volatiles metabólicos para distinguir las enfermedades en los tubérculos almacenados.

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