ABSTRACT
Endophytes are fungi or bacteria living inside plants without eliciting symptoms or disease, common to a large number of plant species (Petrini, 1986; Schulz et al., 1993; Redlin and Carris, 1996). Hundreds of fungal and bacterial species can be detected in a coniferous host, living in buds, leaves, wood, and bark of trees (Petrini, 1986; Fisher and Petrini, 1990; Kowalski and Kehr, 1992; Müller and Hallaksela, 1998, 2000; Pirttilä et al., 2003). Also conifer roots are inhabited by various endophytic microorganisms (Addy et al., 2005). Most of the endophytes form local infections and are transmitted horizontally via spores, and their ecological roles in relation to host tree are suggested to vary from latent pathogens or saprophytes to neutral commensalists or sometimes even mutualists (e.g., via defensive mutualism) (Arnold, 2007; Saikkonen, 2007; Sieber, 2007).
