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Carbon, nitrogen and pH regulate the production and activity of a polygalacturonase isozyme produced by Penicillium expansum

Jurick, Wayne M., Vico, Ivana, Gaskins, Verneta L., Peter, Kari A., Park, Eunhee, Janisiewicz, Wojciech J., Conway, William S.
Archives of Phytopathology and Plant Protection 2012 v.45 no.9 pp. 1101
Penicillium expansum, ammonia, apples, carbon, clones, complementary DNA, enzyme activity, fruits, genes, glutamates, glutamine, isoelectric point, isozymes, metabolism, nitrogen, nutrient uptake, pH, pectins, polygalacturonase
The influence of carbon, nitrogen and pH on polygalacturonase activity produced by Penicillium expansum were investigated. P. expansum mycelial growth was greatest on lyophilized fruit tissue and the highest PG activity occurred in apple pectin medium. Nitrogen source influenced PG activity and was highest with ammonia while the greatest mycelial mass was supported by glutamate or glutamine. PG activity and mycelial mass peaked 5 days after inoculation as polyuronide content decreased and the pH and ammonium levels increased in apple pectin medium. A single active PG isozyme with an isoelectric point of ~7.6 was produced in apple pectin medium and a partial cDNA clone was obtained that was most homologous to the pggII gene from P. griseoroseum. The results from this study indicate that P. expansum can modulate the activity of PG in response to nutrient sources and ambient pH through signaling pathways that modulate nutrient acquisition, uptake and metabolism.