Analysis of genetic diversity in Monilinia fructicola from the Ebro Valley in Spain using ISSR and RAPD markers.

The genetic diversity of Spanish and French field populations of Monilinia fructicola, a quarantine fungal pathogen in Europe, was compared with that of Californian, Uruguayan, and New Zealand M. fructicola populations using inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers. Unweighted pair-group method with arithmetic average (UPGMA) cluster analysis and principal component analysis (PCA) of the ISSR data set revealed that the Spanish and French M. fructicola isolates were more closely related between themselves than to the non-European isolates. The levels of genetic diversity in the Spanish and French isolates are lower than those of the non-European isolates, indicating that M. fructicola is a recently introduced pathogen. UPGMA cluster analysis and PCA of the combined ISSR + RAPD data set of the European M. fructicola populations revealed that the Spanish isolates were more closely related among themselves than with the French isolates. Analysis of molecular variance partitioned the genetic variance to among the two regions (Spain and France) (20%), among the regional populations (35%), and within the populations in each region (45%) suggesting restricted gene flow between the three European populations. The observed index of association (I) in each European M. fructicola populations indicates that the French and Spanish populations of M. fructicola are mainly asexually reproducing, with the Sudanell population potentially having a teleomorphic stage. The present finding of low genetic diversity in the Spanish and French M. fructicola populations is probably due to founder effects and genetic drift. [ABSTRACT FROM AUTHOR]