Rapid purification of host-specific pathotoxins from Alternaria alternata f. sp. lycopersici by solid-phase...

A simplified, rapid procedure for the purification of two phytotoxic metabolites (TA and TB) from cell-free culture filtrates of Alternaria alternata f. sp. lycopersici was developed using hydrophobic chromatography on macroporous, C18 bonded silica followed by gel filtration. Baseline separation of TA from TB was achieved in the final preparation and yields of 80% were obtained with retention of full biological activity in all assay systems tested. Toxin analysis by nuclear magnetic resonance and high-performance liquid chromatography indicated TA was at least 99% pure. The efficiency of the procedure allows rapid accumulation of pure TA and TB for studies on the molecular mode of action and host plant response to this novel host-specific phytotoxin.