Impacts of chitinase-transformed silver birch on leaf decomposition and soil organisms

Genetically manipulated silver birch (Betula pendula) leaves were used in microcosms experiments to evaluate their impacts on different groups of decomposing soil fauna. Birches were transformed to produce chitinase IV from sugar beet. We compared decomposition rates of leaves, growth and reproduction of soil fauna deriving nutrition from these leaves. Population numbers of collembolans (Folsomia candida and Lepidocyrtus lignorum) and nematodes were measured and decomposition rates of the birch leaves were recorded. Woodlice (Porcellio scaber) juveniles living in the microcosms were weighed at 2- to 4-week intervals to determine growth rate. This study revealed that birch leaves manipulated to produce chitinase affected negatively to the numbers of nematodes and positively on numbers of collembolans. Total decomposing rate and leaf mass loss per nematode were highest in chitinase leaves. No differences in growth or survival of woodlouse juveniles between transgenic and control birches were detected.