Isolation and partial purification of phytotoxins from liquid cultures ofLeucostoma cinctaandLeucostoma persoonii

摘要

Phytotoxins fromLeucostoma persooniiandLeucostoma cinctawere 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 1000-Da fraction was tested in a peach shoot tip bioassay. Analytical polyacrylamide isoelectrofocusing of the 1000-Da fraction in the pH range 3.5ndash;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.Key words: Cytospora spp., cytospora canker,Prunus persica, peach.