Evolutionary Relationships among theFusarium oxysporumf. sp.cubenseVegetative Compatibility Groups

Abstract

Fusarium oxysporum f. sp. cubense, the causal agent of fusarium wilt of banana (Musa spp.), is one of the most destructive strains of the vascular wilt fungus F. oxysporum. Genetic relatedness among and within vegetative compatibility groups (VCGs) of F. oxysporum f. sp. cubense was studied by sequencing two nuclear and two mitochondrial DNA regions in a collection of 70 F. oxysporum isolates that include representatives of 20 VCGs of F. oxysporum f. sp. cubense, other formae speciales, and nonpathogens. To determine the ability of F. oxysporum f. sp. cubense to sexually recombine, crosses were made between isolates of opposite mating types. Phylogenetic analysis separated the F. oxysporum isolates into two clades and eight lineages. Phylogenetic relationships between F. oxysporum f. sp. cubense and other formae speciales of F. oxysporum and the relationships among VCGs and races of F. oxysporum f. sp. cubense clearly showed that F. oxysporum f. sp. cubense's ability to cause disease on banana has emerged multiple times, independently, and that the ability to cause disease to a specific banana cultivar is also a polyphyletic trait. These analyses further suggest that both coevolution with the host and horizontal gene transfer may have played important roles in the evolutionary history of the pathogen. All examined isolates harbored one of the two mating-type idiomorphs, but never both, which suggests a heterothallic mating system should sexual reproduction occur. Although, no sexual structures were observed, some lineages of F. oxysporum f. sp. cubense harbored MAT-1 and MAT-2 isolates, suggesting a potential that these lineages have a sexual origin that might be more recent than initially anticipated.

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana

“…They also, undergo frequent mutations (Fourie et al 2009). These recent reports signal the need for understanding evolution of Fusarium strains which would help in developing strategies to combat disease.…”

Molecular fingerprinting of Fusarium oxysporum f. sp. passiflorae isolates using AFLP markers

“…Earlier research suggested genetic exchanges between and within individual lineages. Fourier et al (2009), studying the relationships between VCG of FOC, demonstrated recombination of genetic material within some lineages of this pathogen, which must be due to parasexuality or heterokaryosis between individuals with very similar genomes.…”

Classification of physiological races of Fusarium oxysporum f. sp. phaseoli in common bean

“…Other authors also relate the same results: analyzing molecularly the isolates of Fusarium oxysporum, they found that the isolates of the same geographic region were grouped in different similarity groups and don not have identical fingerprints (Silva et al, 2013). These results can be explained by the parasexuality created by high mutation rates, according to Fourie et al, (2009), who related the existence of the recombination between lineages of Fusarium oxysporum and the relations between VCGs that occurred because of the genome similarity with the evidence of heterokaryosis.…”