Patho toxins produced in vitro by brazilian isolates of helminthosporium maydis
De Carvalho M.G.
Revista de Microbiologia 11(3): 97-103
Culture extracts of races T and O from 2 Brazilian isolates of H. maydis were studied to understand the nature of the compounds most active in pathogenesis. Through extraction and concentrations with organic solvents, lyophilization, acidic hydrolysis of eluate fractions from column chromatograms, and analysis by paper chromatographic methods, distinct, biologically active peptides were found associated with the race T isolate, and at least 1 with the race O isolate. The peptide(s) produced by race T, specifically pathotoxic to male-sterile cytoplasm (maize), came from tube 8 (out of 24 eluate fractions from the Sephadex column) and comprised at least 6 amino acid residues. Its MW was about 700. The other 2 peptides, 1 for each race, were associated with the last column fractions and detected in higher amounts than the race T pathotoxic one. They showed no effect on 2 types of maize tested although clearly inhibitory to conidial germination of Gloeosporium sp., in a test intended as an additional bioassay.