Abuelgasim Elzein, Frank Brändle, Georg Cadisch, Jürgen Kroschel, Paul Marley, Marco Thines
(AE) Institute for Plant Production and Agroecology in the Tropics and Subtropics (380), University
of Hohenheim, D-70593 Stuttgart, Germany; Tel: +49-711-45924346; Fax: +49-711-45922304; E-mail: email@example.com and (MT) Institute
of Botany (210), University of Hohenheim, D-70593 Stuttgart, Germany.
Fusarium oxysporum isolates (Foxy 2 and PSM197) are potential, highly host specific mycoherbicides for the
control of the parasitic weeds Striga hermonthica and S. asiatica. Their target weeds, Striga spp., are major biotic constraints
in cereal and legume production in semi-arid tropical Africa, where they adversely affect livelihood of millions of
subsistence farmers. The aim of this study was to characterize and sequence the Striga mycoherbicides Foxy 2 & PSM197
in order to more clearly distinguish them from other morphologically similar pathogenic Fusarium oxysporum strains. The
fungal isolates were cultivated on PDA medium and characterized based on the analysis of partial DNA sequence of the
internal transcribed spacer (ITS) regions of the nuclear ribosomal RNA gene. Both isolates were identical in their ITSsequence.
The unique and identical ITS-sequence of the two isolates obtained, compared to the sequences of Fusarium
oxysporum forma speciales deposited in GenBank along with the host specificity to Striga demonstrated in previous studies,
provides strong evidence to propose these pathogens of Striga as a new forma specialis (f. sp. strigae). The possibility
to clearly distinguish between the new forma specialis and all pathogenic Fusarium oxysporum strains sequenced so far
will facilitate and encourage the acceptance and introduction of Striga-mycoherbicides for practical field application by
regulatory authorities and farmers.