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Production of a proteinaceous phytotoxin by Ascochyta rabiei grown in expressed chickpea sap
Author(s) -
CHEN Y.M.,
STRANGE R. N.
Publication year - 1994
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.1994.tb02691.x
Subject(s) - phytotoxin , toxin , chromatography , acetone , hydrolysis , biology , molecular mass , amino acid , hydrolysate , extraction (chemistry) , ammonium , high performance liquid chromatography , biochemistry , chemistry , organic chemistry , enzyme
Production of the solanapyrone toxins by Ascochyta rabiei is nutrient dependent. When grown on a medium consisting entirely of expressed sap from the aerial parts of young chickpea plants (PSM). only low concentrations of the solanapyrones were produced (< 24 μM). However, toxicity of 4‐day‐old culture filtrates to isolated cells of chickpea leaflets was comparable with that obtained from 12‐day‐oId culture filtrates on Czapek Dox nutrients supplemented with chickpea seed extract or cations—media that are conducive to solanapyrone production. The additional toxic component which peaked at 4 days in culture was heat labile, losing about 50% of its activity on boiling for 10 min. Affinity for solid‐phase extraction media, precipitation with ammonium sulphate and acetone, ionization properties and UV absorption characteristics suggested that the toxin was a polypeptide. The toxin was purified by solid‐phase extraction, acetone precipitation and high performance liquid chromatography (HPLC) on a C2 column. Hydrolysis of the purified toxin yielded 14 amino acids, and calculation of the numbers of residues of each amino acid suggested a molecular mass of 7, 551 Da, A band corresponding to this molecular mass was present on SDS‐PAGE gels. However, both the native peptide and its hydrolysate contained a compound that reacted with p ‐anisaldehyde suggesting the possibility of a glycosidic moiety.