Identification and Characterization of Fusarium mexicanum Causing Mango Malformation Disease in Mexico

The following is a summary of Fusaria associated with mango malformation disease (MMD) in Mexico. From 2002 to 2009, 142 strains were isolated from symptomatic mango inflorescences and vegetative tissues from various cultivars in eight geographically diverse Mexican states. Initially, isolates were screened for genetic diversity using arbitrarily primed-PCR and RAPD DNA markers. At least seven genetically diverse MMD-associated genotypes were detected, one of which predominated (92 of 141). Maximum parsimony analyses of a five-locus dataset comprising 5.8 kb of aligned DNA sequence data indicated that at least three phylogenetically distinct Fusaria within the American clade of the Gibberella fujikuroi species complex (GFSC) may be associated with MMD. These included F. sterilihyphosum and two undescribed species. These analyses also revealed that one of the undescribed species within the American clade of the GFSC, which we formally described as Fusarium mexicanum, appeared to be the most common MMD-associated species in Mexico. PCR primers for the specific detection of the MMD pathogens F. sterilihyphosum and F. mangiferae failed to detect F. mexicanum. This novel, genealogically exclusive species was also distinguished morphologically. In addition, Koch's postulates were completed for this species via a pathogenicity experiment which demonstrated that it could induce malformation on nucellar seedlings of cultivar 'Ataulfo'.