Analysis of Genetic Diversity of Fusarium tupiense, the Main Causal Agent of Mango Malformation Disease in Southern Spain

Mango malformation disease (MMD) has become an important global disease affecting this crop. The aim of this study was to identify the main causal agents of MMD in the Axarquia region of southern Spain and determine their genetic diversity. Fusarium nzangiferae was previously described in the Axarquia region but it represented only one-third of the fusaria recovered from malformed trees. In the present work, fusaria associated with MMD were analyzed by arbitrary primed polymerase chain reaction (ap-PCR), random amplified polymorphic DNA (RAPD), vegetative compatibility grouping (VCG), a PCR screen for mating type idiomorph, and phylogenetic analyses of multilocus DNA sequence data to identify and characterize the genetic diversity of the MMD pathogens. These analyses confirmed that 92 of the isolates were F. tupiense, which was previously only known from Brazil and Senegal. In addition, two isolates of a putatively novel MMD pathogen were discovered, nested within the African Glade of the Fusarium fujikuroi species complex. The F. tupiense isolates all belonged to VCG I, which was first described in Brazil, and the 11 isolates tested showed pathogenicity on mango seedlings. Including the prior discovery of F. mangiferae, three exotic MMD pathogenic species have been found in southern Spain, which suggests multiple independent introductions of MAID pathogens in the Axarquia region.