Transgenic Betula pendula expressing sugar beet chitinase IV forms normal ectomycorrhizae with Paxillus involutus in vitro

Abstract Mycorrhizal fungi contain chitin in their cell walls and may be influenced by transgenic chitinases. This study examined the ability of a transgenic tree, silver birch (Betula pendula Roth), constitutively expressing the sugar beet chitinase IV gene, to form ectomycorrhizae with Paxillus involutus (Batsch) Fr. Eight transgenic lines showing varying levels of sugar beet chitinase IV expression and the non-transgenic control plants were inoculated by P. involutus in vitro, and the morphology of the mycorrhizae, mycorrhization efficiency and shoot and root fresh weights were studied. All the transgenic birch lines were able to form normal ectomycorrhizae containing distinctive mantles and Hartig nets. The level of sugar beet chitinase IV expression had no significant influence on mycorrhizal colonization. The only significant differences between transgenic and control plants were detected in weight parameters. According to these results, the expression of sugar beet chitinase IV in silver birch is n...