Genetic and phenotypic differences of Fusarium oxysporum f. sp . citri isolated from sweet orange and tangerine.

Fusarium oxysporum f. sp citri is a new soil-borne pathogen of mature citrus trees in Tunisia. ISSR and RAPD markers were used in this study to characterize strains of Fusarium oxysporum from citrus in Tunisia. Pathogenicity assays revealed that Fusarium oxysporum isolates caused from 32 to 95 % disease on seedlings of Citrus aurantium. Results showed that pathogenic isolates were classified into two groups on the basis of ISSR and RAPD fingerprints, suggesting a level of genetic specificity and diversity not previously identified on Fusarium oxysporum f. sp citri. Cluster analysis, principal coordinate analysis and population structure indicated that the different isolates appears to be related only to the host. Potential primers related to ISSR markers could be selected to characterize Tunisian strains of Fusarium oxysporum and determine genetic differences of the pathogen virulence. With this investigation we characterize Fusarium wilt on citrus trees by the mean of ISSR and RAPD markers. [ABSTRACT FROM AUTHOR]