Separation of phenotypically related strains of pathogenic and nonpathogenic Fusarium oxysporum on the basis of free amino acid profiles and extracellular enzymatic activities

anglais. Free amino acids profiles of cell lysates and extracellular cellulolytic and pectolytic enzyme activities of pathogenic and nonpathogenic strains of Fusarium oxysporum were employed as chemo- and bio-taxonomic criteria. Particular nonprotein amino acids were found to be a unique feature of the profile of each strain, especially the nonpathogenic strains (C5 and C14). Amino acid profiles from host-closely related strains revealed a higher degree of homogeneity when compared with host-distinctly related strains. Comparing extracellular cellulolytic and pectolytic enzymatic activities, in the context to separate among morphologically-similar strains, concluded similar and consistent results. However, despite repeated trials, no amino acid or enzymatic pattern unique to pathogenicity and virulence were detected. Thus, these finding confirm and extend the previous information in supporting the contention that variations are distinct enough to separate between strains C5 and C14 into biologically different genotypes. Our data accordingly suggest the potential use of thin layer chromatography as a reliable tool in claryfing the overlaps and confirming genetic affinity in strains of F. oxysporum grouped by morphological characters

italien. I profili degli aminoacidi liberi dei lisati cellulari e le attivita' degli enzimi cellulolitici e pectolitici sono stati usati come criteri chemo e bio-tassonomici su ceppi patogeni e non di Fusarium oxysporum. Un profilo caratteristico degli aminoacidi non proteici e' stato riscontrato in ciascun ceppo studiato, specialmente per quelli non patogeni (C5 e C14). Tuttavia, i profili ottenuti da ceppi isolati dalla stessa specie vegetale mostrano grado di omogeneita' piu' elevato rispetto a quelli relativi a ceppi provenienti da ospiti tassonomicamente differenti. Analoghi risultati sono stati ottenuti comparando le attivita' cellulolitiche e pectolitiche extracellulari. Comunque, nonostante le ripetute prove, non sono stati individuati aminoacidi o profili enzimatici caratteristici per la patogenicita' e virulenza. I risultati confermano la separazione, gia' emersa precedentemente, dei ceppi C5 e C14 in due genotipi biologicamente differenti