engleski

Laccase activity change in cryphonectria hipovirus 1-infected cryphonectria parasitica is influenced by culture conditions, fungal isolate and virus strain

In chestnut blight fungus Cryphonectria parasitica, laccase, a polyphenol oxidase, is thought to be involved in pathogenesis towards chestnut due to its ability to degrade lignin, which is intensively synthetized by chestnut trees as a defensive reaction. Infection with virus Cryphonectria hypovirus 1 (CHV1), a hyperparasite of C. parasitica, has been shown to reduce laccase activity of infected fungus, reducing its virulence towards chestnut. Thus far the research has been done on only limited number of fungal isolates and virus strains. Objectives Our aim was to determine the effect of local CHV1 strains on laccase activity in different Croatian C. parasitica isolates, which could have important implications in choosing the optimal virus strain for human aided biocontrol of chestnut blight. Three CHV1 strains were transferred to three Croatian isolates of C. parasitica by hyphal anastomosis. The cultures were grown on potato dextrose agar and broth, and laccase activity was assayed with 2, 2'-azino-bis(3-etilbenzotiazoline-6-sulphonic acid) as a substrate. For cultures grown on solid medium total laccase activity was measured, and for cultures grown in liquid medium extra- and intracellular laccase activity was measured. Conclusions: When grown on solid medium, total laccase activity of CHV1-infected fungal isolates increased compared to control, virus-free isolates. In liquid medium extracellular laccase activity either increased or decreased, depending on fungal isolate, while the intensity of the change depended on the virus strain. Intracellular laccase activity of isolates grown in liquid medium showed almost no responsiveness to CHV1 infection. Thus we conclude that C. parasitica laccase activity depends on more parameters than just the CHV1 infection.

fungal laccase ; hypovirus ; mycovirus-host interaction

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