Pathogenicity and race characterization of Fusarium oxysporum f. sp. phaseoli isolates from Spain and Greece

Abstract

Virulence ( ≡ severity of disease) and physiological specialization of nine isolates of Fusarium oxysporum f. sp. phaseoli recovered in El Barco de Avila (Castilla y León, west-central Spain) and of two isolates from Chryssoupolis (Greece) were determined. The susceptibility/resistance response showed by a differential set of common bean cultivars ( Phaseolus vulgaris ) selected at the Centro Internacional de Agricultura Tropical (CIAT) delineated the isolates into two new races: races 6 and 7. The results of pathogenicity tests did not show any significant differences in virulence among the isolates. However, the reactions of several Spanish common bean cultivars indicated the presence of two groups of isolates, highly virulent and weakly virulent, among the Spanish isolates analysed. These results indicate that isolates classified in the same race are not homogeneous with respect to virulence, and suggests that race analysis using the CIAT differential cultivars is insufficient to describe the physiological specialization of F. oxysporum f. sp. phaseoli .

EF-1α gene and IGS rDNA sequencing of Fusarium oxysporum f. sp. vasinfectum and F. oxysporum f. sp. phaseoli reveals polyphyletic origin of strains

“…Our phylogenetic analyses showed that strains from the same formae speciales can have very distinct genetic backgrounds, supporting their polyphyletic origin and confirming the observations of several studies on the origin of formae speciales of F. oxysporum (O'Donnell et al, 1998;Baayen et al, 2000;Alves-Santos et al, 2002a;O'Donnell et al, 2009). Determinants of host-specificity may be horizontally transferred between strains of F. oxysporum of different lineages, resulting in polyphyly.…”

“…A wider range of symptoms was observed for strains of Fov than for Fop. Differences in aggressiveness are common among strains of F. oxysporum and can indicate the occurrence of races within formae speciales (Alves-Santos et al, 2002a;Kim et al, 2005). Since only one cultivar of each host species was used to evaluate the pathogenicity of Fov and Fop, the existence of different races among the strains in the present study could not be confirmed but the genetic diversity revealed by the phylogenetic analyses supports such possibility.…”

“…Seven races of Fop have been described based on the virulence to up to eight bean cultivars (Ribeiro & Hagedorn, 1979;Aloj et al, 1987;Woo et al, 1996;Alves-Santos et al, 2002a). Relationship between race and geographic origin has been observed with race 1 occurring in the USA (South Carolina) and Italy, race 2 in Brazil, race 3 in Colombia, race 4 in the USA (Colorado), race 5 and 7 in Greece, and race 6 in Spain.…”

Resistance to Fusarium wilt in common bean

“…Pereira et al (2013) inoculated FOP UFV 01 in differential cultivars of beans, proposed by Woo et al (1996) and Alves-Santos et al (2002), and concluded that this isolate is a new race of the species. FOP UFV 01 inoculum was produced with PDA (potato -dextrose -agar) discs containing mycelia that were transferred to Petri dishes containing PDA.…”

Inheritance of resistance to Fusarium oxysporum f. sp. phaseoli Brazilian race 2 in common bean

“…Seven pathogen races, well-distributed across the continents, are documented in the literature. In Brazil, there are indications of the predominance of one race, designated race 2 (Alves- Santos et al, 2002).…”