The ToxB gene was cloned and characterized from a race 5 isolate of Pyrenop
hora tritici-repentis from North Dakota. ToxB contains a 261-bp open readin
g frame that encodes a 23 amino acid putative signal peptide and a 64 amino
acid host-selective toxin, Ptr ToxB. Analysis of Ptr ToxB from heterologon
s expression in Pichia pastoris confirms that ToxB encodes a host-selective
toxin.