Development of a PCR-based assay for the detection of Fusarium oxysporum strain FT2, a potential mycoherbicide of Orobanche ramosa.

Orobanche ramosa is an important parasitic weed of several agriculturally important crops. A fungal strain identified as Fusarium oxysporum (named FT2) proved to be specific and highly virulent to O. ramosa plants and was proposed as a mycoherbicide for the biological control of this weed to be applied at the soil level. Considering that detecting and tracking the strain is of utmost importance to know the fate of the strain after its release, an amplified fragment length polymorphism (fAFLP) analysis was chosen and utilized with the aim to develop a molecular marker to specifically identify this strain. A wide population of F. oxysporum strains isolated from different hosts was screened against the mycoherbicide strain in order to identify specific fragments belonging to this strain. Two specific fragments were found and their DNA sequences were utilized for primer design. A primer pair (named FT2230F/FT2230R) proved to be strain specific and it amplified a 232 bp DNA fragment of FT2. These primers were used to monitoring the presence of the F. oxysporum strain in the soil. Amplicons were detected from all the soil samples artificially infected by using known amounts of FT2 inoculum, whereas none of the primer sets amplified DNA from soils not infected by FT2.