Journal of Plant Pathology Archive

Abstract:

Fusarium wilt disease of carnation is one of the most im- portant diseases in all major carnation growing regions of Iran. This fungal disease is caused by Fusarium oxysporum f. sp. dianthi W.C. Snyder & H.N. Hansen. In 2011, an exten- sive sampling was carried out from carnation greenhouses in two Iranian provinces (Tehran and Markazi). Fungal iso- lates were identified as F. oxysporum based on morphological characters (Nelson et al., 1983). Pathogenicity tests were per- formed by root dipping carnation cuttings of the susceptible cv. Rendezvous. Controls were included by dipping carna- tion cuttings in sterile distilled water. All inoculated plants developed wilt symptoms after 50 days of incubation at 28 to 30°C. Fifty isolates were selected randomly for further molecular characterisation by comparison with eight F. oxy- sporum f. sp. dianthi isolates from Italy (courtesy of Professor A. Garibaldi), which were used as reference for races 1, 2, 4 and 8. F. oxysporum f. sp. dianthi races were identified by PCR amplification of transposon insertions (Chiocchetti et al., 1999). DNA was amplified using primers Ft3, R4.2, R8.1, R2.1 and IMP2 as described. Amplified fragments of 295 bp and 564 bp corresponded to races 1 (or 8, since the primers used do not allow discrimination between these two near- isogenic races) and to race 2, respectively. Of fifty isolates, 42 were identified as belonging to race 2 and two isolates were identified as race 1 (or 8). None of the tested isolates be- longed to race 4. Six isolates did not generate any amplifica- tion by using the tested primers. To the authors’ knowledge, this is first report of detection of Fusarium oxysporum f. sp. dianthi races in Iran.