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Research was conducted to examine the targeted mutants of Cochliobolus carbonum lacking the two major extracellular polygalacturonases (exoPG). The purification of the exoPG activity of C carbonum and the cloning of its gene, PGX1, was also performed. Double pgn1/pgx1 mutant strain was developed by crossing. The continued growth of the pgn1/pgx1 mutant strain on pectin could be attributed to one or more of PG residual activities.

Mixed-linked glucanases (MLGases) or extracellular enzymes that degrade beta-glucan from the fungus Cochliobolus carbonum were identified and characterized. Three peaks of MLGase activity, named Mlg1a, Mlg1b and Mlg2, were resolved by hydrophobic-interaction high performance liquid chromatography and cation-exchange. Results showed that the N-terminal amino acid sequences of Mlg1a and Mlg1b were identical. Mlg1a was glycosylated while Mlg1b was not. Mlg1a and Mlg1b hydrolyzed beta1,3-glucan while Mlg2 did not.

The filamentous fungi Cochliobolus carbonum contains three cationic xylanases, XYL1, XYL2 and XYL3 that encode for the extracellular 22-kDa family of G xylanases. XYL1 and XYL3 mRNA's are present in infected plants. XYL2 and XYL3 have no contribution towards the extracellular xylanase activity. Multiple xylanase disruptions are produced by crossing single xylanase mutants. The triple mutant is still pathogenic on maize as evident from its lesion size, morphology and rate of lesion development.

Cochliobolus carbonum, the phytopathogenic fungus, generates an enzyme that degrades beta1,3-glucanase, and the purified enzyme is used to isolate the gene EXGI from genomic DNA. EXG1 mutant growth is normal on oat bran and sucrase, but reveals a 65% decrease on pure beta1, 3-glucan. EXG1 mutant has been found to be pathogenic to maize.