A new Fusarium lineage within the Gibberella fujikuroi species complex is the main causal agent of mango malformation disease in Brazil

Abstract

Mango malformation is a serious disease in tropical and subtropical areas of the world and has been attributed to various Fusarium spp., including F. mangiferae, F. proliferatum, F. sacchari, F. sterilihyphosum and F. subglutinans. Isolates of Fusarium associated with mango malformation from Brazil, Egypt, India, South Africa and the United States were evaluated through amplified fragment length polymorphisms (AFLPs) and partial DNA sequences of the genes encoding β‐tubulin (tub2) and translation elongation factor 1‐α (tef1). These techniques were used to delimit species and to estimate the genetic and phylogenetic relatedness of the isolates. In the AFLP analysis, most of the Brazilian isolates formed a unique cluster. Additionally, one small cluster was formed by isolates of F. sterilihyphosum from Brazil and South Africa, and another by isolates of F. mangiferae from Egypt, India, South Africa and the United States. In the phylogenetic analysis, most of the Brazilian isolates represented a new phylogenetic lineage in the Gibberella fujikuroi species complex, where they formed a sister clade to F. sterilihyphosum. Representatives of both clades were pathogenic to mango (cv. Tommy Atkins) and Koch's postulates were completed for isolates belonging to the new lineage and to F. sterilihyphosum. Thus, most of the mango malformation disease in Brazil is due to a distinct phylogenetic lineage of Fusarium, and to a lesser extent by F. sterilihyphosum. The new phylogenetic lineage identified in this study, together with F. mangiferae and F. sterilihyphosum, are the only known taxa of Fusarium proven to be capable of causing mango malformation.