FIRST REPORT OF SESAME WILT DISEASE CAUSED BY FUSARIUM PROLIFERATUM IN IRAN
M. Torabi, M. Ghorbany, M. Salari, M.R. Mirzaee
In July 2012 a survey was conducted to determine the fungal agents of wilt and crown rot disease of sesame in South Khorasan province, Iran. Fusarium proliferatum (T. Matsushima) Nirenberg ￼ was isolated and identified based on morphological characteristics on PDA, CLA and SNA culture media (Nirenberg and O'Donnell, 1998; Leslie and Summerell, 2006) from 47% of infected tissues. Colonies were fast growing, forming abundant aerial mycelium, with colorless to dark purple appearance on colony reverse. On CLA, club-shaped and single-celled microconidia were formed in chains and in conidial heads arising from mono-phialides and poly-phialides, the macroconidia were slender, almost straight, and usually 3-5 septa. Chlamydospores were absent. The internal transcribed spacer (ITS) region of ribosomal DNA was amplified using fungal-specific primer pair ITS1F/ITS4 and the PCR product was sequenced. Comparison of the sequence (GenBank accession No. KM459007) revealed 100% similarity to F. proliferatum (GenBank accession Nos AF291061 and HQ607967). Pathogenicity of the fungus was confirmed by inoculating 2-week-old seedlings of Oltan cultivar with an adjusted conidial suspension. Symptoms similar to those observed in the field appeared on inoculated seedlings. The fungus was consistently re- isolated from symptomatic plants, while controls remained symptomless. To our knowledge, this is the first report of F. proliferatum causing sesame wilt disease in Iran.