Study of Onion Seed Borne Fusarium in Razavi and Northern Khorasan

Fusarium species are one of the most important pathogens on onion in Iran and out of whit few are transmitted by onion seeds. In order to identify onion seed borne Fusaria in Razavi and Northern Khorasan provinces, in the September 2007 seed samples from different field of four localities were studied using cultural media, greenhouse assay and molecular technique respectively. In the first experiment surface disinfested and nonsterlized onion seeds were cultured on PDA, in the second experiment surface disinfested seeds were planted in outoclaved soil under greenhouse condition.. F. proliferatum and F. oxysporum were detected and isolated from seeds cultured on PDA and seedlings grown in greenhouse. The rate of F. proliferatum transmitted by seed found to be 0-15 and 0- 6.7 % on PDA and greenhouse respectively, while it was between 0-48 and 0-10 %. for F. oxysporum. For molecular studies after extracting F. proliferatum DNA isolated from seed samples and performing PCR by selecting specific primers, molecular weights of bands on agarose gel were compared using the labwork 3,0,2 software. Distinctive difference were observed between molecular weights of bands from diverse regions. A positive significant correlation was also observed between the results of culture media and molecular methods. The result of this study confirmed that F. proliferatum and F. oxysporum are both seed borne on onion.