FIRST REPORT OF SESAME WILT DISEASE CAUSED BY FUSARIUM PROLIFERATUM IN IRAN

Abstract

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 monophialides and poly-phialides, the macroconidia were slender, almost straight, and usually 3-5 septate. 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-weekold 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.