8 Afra Khiralla, Rosella Spina, Sakina Yagi et al.
Avoiding abiotic stressOne attribute that appears unique to Class II NC-endophytes is the ability
of individual isolates to asymptomatically colonize and confer habitat-adapted,
fitness benefits on genetically distant host species representing monocots and
eudicots (Rodriguez et al., 2009). This phenomenon was discovered by
comparing fitness benefits conferred by Class II endophytes in plants growing
in geothermal soils Curvularia protuberate, coastal beaches Fusarium
culmorum and agricultural fields Colletotrichum spp. (Redman et al., 2002;
Márquez et al., 2007).
Increase of biomassMost of class II endophytes examined have increased host shoot and/or
root biomass. Tudzynski and Sharon (2002) stated that this was a result of the
induction of plant hormones by the host or biosynthesis of plant hormones by
the fungi.
Protection from fungal pathogensMany endophytes of class II protect hosts to some extent against fungal
pathogens (Danielsen and Jensen, 1999; Narisawa et al., 2002; Campanile et
al., 2007) by different strategies like production of secondary metabolites
(Schulz et al., 1999). Few studies revealed interactions with host defenses;
fungal parasitism (Samuels et al., 2000); induction of systemic resistance (Vu
et al., 2006); or competition with endophytes for resources or niche space.
5. ENDOPHYTES VERSUS EPIPHYTES
Endophytes are often contrasted with epiphytes, which live on external
plant surfaces (Santamaria and Bayman, 2005). In practice, the distinction is
that epiphytes can be washed of plant surfaces or be inactivated by surface
disinfection, usually with sodium hypochlorite and ethanol to break surface
tension, whereas endophytes cannot. Thus, an epiphyte that survives surface
disinfection and grows in culture might be assumed to be an endophyte
(Arnold and Lutzoni, 2007). Although there are few studies comparing
phylloplane and endophytic fungal communities of the same leaves,