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Physiology and Biochemistry

Polypeptides Associated with Gliotoxin Production in the Biocontrol Fungus Gliocladium virens. C. J. Ridout, Biocontrol of Plant Diseases Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705-2350, Present address: School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; R. D. Lumsden, Biocontrol of Plant Diseases Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705-2350. Phytopathology 83:1040-1045. Accepted for publication 27 May 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1993. DOI: 10.1094/Phyto-83-1040.

Two polypeptides (18.7- and 33.8-kDa) were purified from mycelial extracts of Gliocladium virens G20 with two-dimensional electrophoresis and used for the production of antiserum in the eggs of turkey hens. The resulting antisera were used to investigate the association of these polypeptides with gliotoxin production in G. virens. Mycelia from 20 strains of G. virens and three other gliotoxin-producing fungal genera were extracted into denaturing electrophoresis buffer and analyzed with immunoblotting procedures. Both polypeptides were detected in mycelial extracts from 15 strains that produced gliotoxin but were not detected in extracts from five strains that did not produce gliotoxin or in extracts from three other fungal genera. Antiserum against the 33.8-kDa polypeptide also reacted against mycelium of G. virens G20 extracted into nondenaturing Tris-HCl buffer. Gliotoxin was detected in the culture filtrate of G. virens grown in Weindling's medium after incubation of germinating chlamydospores for 24 h, whereas the 18.7-kDa polypeptide was detected in denatured mycelial extracts of G. virens after 16 h of growth. The 33.8-kDa polypeptide was detected after growth of germinating chlamydospores for 64 h. The chlamydospores contained two polypeptides (78- and 100-kDa) that cross-reacted with the antiserum raised against the 33.8-kDa polypeptide. These results may facilitate the identification and characterization of genes expressed during the production of gliotoxin by G. virens.