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Degradation of Corn Cell Walls by Extracellular Enzymes Produced by Helminthosporium maydis Race T. D. F. Bateman, Department of Plant Pathology, Cornell University, Ithaca, New York 14850; T. M. Jones(2), and O. C. Yoder(3). (2)(3)Department of Plant Pathology, Cornell University, Ithaca, New York 14850. Phytopathology 63:1523-1529. Accepted for publication 18 June 1973. DOI: 10.1094/Phyto-63-1523.

Endopolygalacturonase and endoxylanase were produced by Helminthosporium maydis race T growing on a mineral salts-glucose medium at 23 C. Pectin lyase (endopectin methyl-trans-eliminase) with a pH optimum of about 8.5 was produced by the fungus on potato broth-Na polypectate or mineral salts-glucose-Na polypectate media. The endopolygalacturonase exhibited a pH optimum of 4.8, a pI of 8.3, and released mono-, di-, tri-, and higher oligomers of D-galacturonic acid from Na polypectate; this enzyme induced a 50% loss in viscosity of 1% Na polypectate at 30 C with about 0.1% hydrolysis. The xylanase system had a pH optimum between 4 and 6. It released D-xylose and oligomers of D-xylose from xylan. Within 2 hr at 30 C, culture filtrates of H. maydis race T grown on the mineral salts-glucose medium released 31% of the galacturonate, 45% of the xylose, and 75% of the arabinose from the trifluoroacetic acid-Sclerotium rolfsii enzyme hydrolyzable portion of cell walls from leaves of 10-day-old corn seedlings.