MOLECULAR RECORDS OF MICRO-EVOLUTION WITHIN THE ALGERIAN POPULATION OF FUSARIUM-OXYSPORUM F-SP ALBEDINIS DURING ITS SPREAD TO NEW OASES

The genetic diversity of the date palm wilt pathogen Fusarium oxysporu m f. sp. albedinis in Algeria was assessed using vegetative compatibil ity, restriction fragment length polymorphism (RFLP) of mitochondrial DNA (mtDNA), and random amplified polymorphic DNA (RAPD). Ninety-eight isolates were collected from the main infested regions, Touat, Gourar a and Mzab, and 6 isolates from Morocco were added for comparison. All isolates were vegetatively compatible and belonged to VCG 0170. No va riation was detected in the mtDNA of a subset of 73 isolates and the R APD analysis indicated that they were genetically very closely related . However, some geographic substructuring was apparent, suggesting tha t local diversification of the pathogen might have occurred. These res ults provide evidence that the Algerian isolates of F. oxysporum f. sp . albedinis belong to a same clonal lineage and support the hypothesis that they were probably founded by a single virulent clone that origi nated from the Moroccan eases where the date palm wilt (Bayoud disease ) was first detected. Based on similarity of RAPD patterns occurring i n different eases, and on historical records of the Bayoud disease in Algeria, spread of the pathogen in the different regions is discussed.