Delivering plasmid DNA into cells to create mutant lines is a
common and well-established procedure for bacteria, plant, and
animal cells. However, this procedure becomes complicated when
it comes to filamentous fungi because the long branching hyphae
cells that form the mycelia are multinucleate. In these fungi,
the introduced DNA plasmid will often integrate into a single
nucleus by either homologous or ectopic recombination, resulting
in heterokaryons that are not suitable for genetic analyses. In
some species, homokaryotic clones can be created by multiple
rounds of single spore isolation; in others, hyphal tip transfer
is required, which depends on extensive technical skills as well
as several culturing rounds before a pure genetic clone is
obtained. Using the plant pathogen Sclerotinia sclerotiorum, Z.
Dallal Bashi, G. Kahachatourians, and D. Hegedus (University of
Saskatchewan, Saskatoon, Canada) developed a technique for
isolating homokaryons following Agrobacterium tumefaciens
transformation using ul