Snyder et Hansen in 1940 simplified nomenclature and taxonomy of the genus Fusarium by minimizing the significance of morphological variation. On the basis of host-specificity they established formae speciales and included them in a single species Foxysporum Schlecht. emend. Snyder et Hansen. Up to date over 120 host-plants of nearly the same number of formae speciales have been recognized. Formae speciales were differentiated by means of pathogenicity tests and additional methods: serological, biochemical, genetic, vegetative compatibility tests and molecular biology analysis, as RFLP and PCR. Recently the differentiation of vegetative compatibility groups (VCGs) seems to be important in the characteristics of formae speciales. A systematic numbering of VCGs was proposed for standarization of the system used for categorizing genetic diversity in Foxysporum. It might be the beginning of a new taxonomic system of Fusarzum oxysporum.
Fruit rot of tomato is a serious disease caused by Fusarium species. Sampling was conducted throughout Selangor, Malaysia and fungal species identification was conducted based on morphological and gene encoding translation elongation factor 1-α (tef1-α) sequence analysis. Five species of Fusarium were discovered namely F. oxysporum (including F. oxysporum f. sp. lycopersici), F. solani, F. equiseti, F. proliferatum and F. verticillioides. Our results provide additional information regarding the diversity of Fusarium species associated with fruit rot disease of tomato.
Activation of the phenolic pathway is known to be part of a defense response against cell wall-derived elicitors from pathogens. Many examples of a defense response by increasing the synthesis of phenolic compound against the elicitor were demonstrated in the past, but the elicitor structure has so far been poorly characterized. Our results indicate that a disaccharide fraction containing the following structure: a-D-mannopyranosyl (1=>2)a/ß-D-glucopyranosyl and a-D-mannopyranosyl (1=>x) inositol, isolated from Fusarium oxysporum L., promotes rapid and transient phenylalanine ammonia lyase activity in Rubus fructicosus cells at nanomolar concentration. The disaccharides were isolated by size-exclusion chromatography directly from extracts obtained by alkaline treatment of F. oxysporum mycelium. Their structure was determined by 500-MHz-1H-NMR spectroscopy combined with methylation analysis and fast atom bombardment mass spectrometry.
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