Archivio Journal of Plant Pathology

Abstract:

A rapid and sensitive molecular diagnostic assay for Fusarium oxysporum f. sp. chrysanthemi, an economically important pathogen of ornamentals, has been developed and tested on three hosts (Gerbera jamesonii, Osteospermum sp., and Argyranthemum frutescens). A specific primer set (B6003/SNR3) was designed on the basis of a single nucleotide polymorphism (SNP) in the FOW1 gene of F. oxysporum f. sp. chrysanthemi. This primer set was highly specific and able to distinguish this fungus from other formae speciales of F. oxysporum. A 304 bp sequence was amplified from DNA of three isolates of F. oxysporum f. sp. chrysanthemi, whilst no amplification was obtained from DNA of 16 other Fusarium species and formae speciales of F. oxysporum. In conventional PCR with primer pair B6003/SNR3, the detection limit of F. oxysporum f. sp. chrysanthemi was 100 pg of genomic, whilst in a semi-nested PCR, using primer pair B6003/B6004 in the first round, and B6003/SNR3 in the second round, the detection limit was as low as 10 fg of genomic DNA. Semi-nested PCR successfully detected F. oxysporum f. sp. chrysanthemi in three artificially infected symptomless host plants sampled three days after pathogen inoculation.