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Deterioration of Stored Pea Seed by Aspergillus ruber: Partial Purification and Characterization of a Toxin to Peas. G. E. Harman, Assistant Professor of Seed Microbiology, Department of Seed Investigations, Cornell University, New York State Agricultural Experiment Station, Geneva, New York 14456; Phytopathology 63:46-49. Accepted for publication 15 July 1972. DOI: 10.1094/Phyto-63-46.

A toxin to peas produced by Aspergillus ruber was extracted from infected living peas and from cultures of A. ruber grown on autoclaved peas. The toxin was partially purified by treatment of aqueous solutions with chromatography on DEAE-Sephadex and Sephadex G-50. The toxin remained in the aqueous phase after treatment with chloroform and butanol. It had a strong negative with chloroform and butanol. It had a strong negative charge at pH values near neutrality, and an apparent molecular weight of 2,000. It was toxic to all cultivars and species of Pisum tested, but did not affect seeds of tomato, lettuce, lima bean, squash, or wheat, embryos of squash or wheat, or lima bean embryonic axes. The most highly purified preparations were active against pea embryonic axes at 0.1 µg/ml. Crude extracts of infected living peas, of cultures of autoclaved peas, and of partially purified preparations of some extracts of living peas also contained another component of larger molecular weight. Crude extracts of autoclaved pea cultures of A. ruber also had toxic activity to lima bean seeds and embryonic axes, but not to any other seeds. This toxicity to lima beans was lost during purification of the pea toxin.