Molecular records of micro-evolution within the Algerian population of Fusarium oxysporum f. sp. albedinis during its spread to new cases

The genetic diversity of the date palm wilt pathogen #Fusarium oxysporum$ f. sp. #albedinis$ in Algeria was assessed using vegetative compatibility, 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, Gourara and Mzab, and 6 isolates from Morocco were added for comparison. All isolates were vegetatively compatible and belonged to VCG 0170. No variation was detected in the mtDNA of a subset of 73 isolates and the RAPD analysis indicated that they were genetically very closely related. However, some geographic substructuring was apparent, suggesting that local diversification of the pathogen might have occurred. These results provide evidence that the Algerian isolates of #F. oxysporum$ s. sp. #albedinis$ belong to a same clonal lineage and support the hypothesis that they were probably founded by a single virulent clone that originated from the Moroccan oases where the date palm wilt (Bayoud disease) was first detected. Based on similarity of RAPD patterns occurring in different oases, and on historical records of the Bayoud disease in Algeria, spread of the pathogen in the different regions is discussed. (Résumé d'auteur