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Abstract

Characterisation and identification of Fusarium foetens, causative agent of wilting and stem rot of begonia elatior hybrids (Begonia x hiemalis) by its volatile compounds.

Five morphologically different isolates of Fusarium foetens were cultivated on potato dextrose agar (PDA), and the fungal volatile compounds were detected and analysed by headspace sorptive extraction (HSSE) followed by gas chromatography / mass spectrometry (GC/MS). Ten sesquiterpenes and five cyclohexane derivatives were detected. Hierarchical cluster analysis enabled the differentiation between red coloured sesquiterpene producing strains and white or pink coloured cyclohexane derivative producing strains. This result has been confirmed by sensory characterisation carried out by sensory trained examiners. Sesquiterpenes 10, 11 and 18 were detected in all isolates of both groups, however, in the first group at a higher level with an average of 88 %-peak area. The patterns of a RAPD-PCR analysis did not show any differences between the isolates. However, RAPD-PCR enables a clear differentiation of Fusarium foetens from Fusarium begoniae and Fusarium oxysporum f. sp. cyclaminis isolates. The combination of both techniques, the HSSE and the RAPD-PCR, provides an improvement in identification of F. foetens and differentiation of its strains. Begonia elatior hybrids (Begonia x hiemalis), cultivar ‚Barkos‘ , were inoculated with a sesquiterpene producing strain of Fusarium foetens and incubated in a moist chamber. The volatile organic compounds were extracted and analysed by using the same methods as for the above-mentioned in vitro experiments. The three sesquiterpenes 10, 11 and 18, previously detected on agar plates, achieved an average of 63 %-peak area. Only traces of the main compounds were detected in extracts from whole infected plants. Therefore, practical application e.g. in the form of a so-called „e-nose“ to help detect infected plants is currently not realistic, but holds promise for the future.



Tschöpe, B.; Hey, M.; Wohanka, W.; Hennig, F. 2007. Characterisation and identification of Fusarium foetens, causative agent of wilting and stem rot of begonia elatior hybrids (Begonia x hiemalis) by its volatile compounds. European Journal of Horticultural Sciences 72 (4), 152-157.