Isolation and partial purification of phytotoxins from liquid cultures of Leucostoma cincta and L. persoonii

A. M. Svircev, Postdoctoral Research Scientist, Horticultural Research Institute of Ontario, Vineland Station, Ontario, Canada L0R 2E0, A. R. Biggs, Associate Professor, West Virginia University, University Experiment Farm, P.O. Box 609, Kearneysville, WV, USA, 25430, and N. W. Miles, Research Scientist, Horticultural Research Institute of Ontario, Vineland Station, Ontario, Canada L0R 2E0

ABSTRACT

Svircev, A. M., Biggs, A. R., and Miles, N. W. 1991. Isolation and partial purification of phytotoxins from liquid cultures of Leucostoma cincta and L. persoonii. Can. J. Bot. 69:1998-2003.

Phytotoxins from Leucostoma persoonii and L. cincta were isolated by sequential ultrafiltration of cell-free culture filtrates through a series of exclusion membranes. Phytotoxic activity, characterized by stem necrosis and leaf wilt, chlorosis and necrosis, was evident when a cold acetone precipitate from the < 1,000 d fraction was tested in a peach shoot tip bioassay. Analytical polyacrylamide isoelectrofocusing of the < 1,000 d fraction in the pH range 3.5 - 6.0 identified two peptide bands at pH 4.0 and 6.0. Preparative granulated bed isoelectric focusing in the same pH range yielded two fractions with phytotoxic activity against peach shoots. Preliminary characterization studies indicate that the two fractions with toxin activity contain small polypeptides.