Fig. 1.

A summary of the transformation process of fungi by Agrobacterium tumefaciens. At step a, acetosyringone present in the transformation media is recognized by the bacterium, triggering b the expression of genes within the chromosomal DNA and from the helper plasmid. At stage c, the T-DNA is excised from the T-plasmid. The linear DNA is bound by VirD2, which is recognised by the type IV secretion system for export from the cell, along with other Vir proteins (d). At step e, the DNA enters the fungal nucleus guided by nuclear localization signals on the bacterial-encoded proteins. In the final event f, the T-DNA inserts into the chromosomal DNA of the fungus. The T-DNA should encode a selectable marker such that the integration events can be selected