Identification of pathotypes in Fusarium oxysporum f.sp lentis

Fusarium oxysporum f.sp. lentis (Fol) is one of the most destructive diseases of lentil (Lens culinaris) worldwide. Although differences in in vitro growth pattern and aggressiveness have been observed in its populations, no pathotypes have been reported so far. The objective of this study was to check for the existence of differences in virulence in Fol and to develop a differential set of lentil accessions able to distinguish the virulence patterns. In a first step 28 lentil-resistant accessions reported elsewhere were inoculated with six isolates of Fol with different geographical origins, which showed a highly significant isolate x accession interaction. Based on their contrasting response, four accessions were selected as a putative differential set. In a second step we characterized the virulence pattern of 52 Fol isolates from Iran, Syria and Algeria using the differential set. This allowed the identification of seven different patterns of virulence, named as pathotypes 1 - 7. Pathotype 7 was virulent on all accessions studied. No correlation was found between the pathotype and the geographical origin of the isolates. This is the first report of the existence of pathotypes in Fol. Based on these results; lentil breeding strategies for resistance to the pathogen should be planned according to the prevalent pathotype present in the region.