Endophytic Fungi 9comparisons within pine and coffee leaves indicate that endophytic
communities are distinct from epiphytic ones, even though they may live less
than a millimeter apart (Santamaria and Bayman, 2005). Temporally as well as
practically, the distinction between endophytes and epiphytes is often
arbitrary. Many horizontally transmitted endophytes presumably start growing
on the surface of the leaf before penetration. Also, endophytes may become
epiphytes when internal tissues are exposed, and may protect the exposed
tissues from the environment. In shoot tip–derived tissue cultures of Pinus
sylvestris, calli were found to be covered by hyphae of the endophytes
Hormonema dematioides, Rhodotorula minuta, and associated biofilms
(Pirttila et al., 2002). How such endophytes coordinate function, interact with
other microbiome biofilm components, and affect plant fitness needs further
exploration.
6. FUNGI AS SOURCE OF BIOACTIVE COMPOUNDS
6.1. Fungal Metabolites
Fungal metabolites are diverse including those associated with proteins
synthesis and respiration. Several secondary metabolites have been isolated
and frequently, chemically defined. Some of these are waste products while
others such as pigments, toxins, and antibiotics clearly have biological
functions. Because of their synthetic abilities, fungi are used in industry for the
production of alcohol, citric acid and other organic acids, various enzymes,
riboflavin, (Kirk et al., 2008).
Schulz et al., (2002) emphasis on fungal endophytes secondary
metabolites. Through 12 years studying endophyte metabolites, they found a
correlation between biological activity of fungal metabolites and biotope. They
reported that a higher proportion of the endophytic fungi exhibited biological
activity than the soil isolates did; whereas 83% of the algal isolates and 80% of
endophytic fungi from plants inhabited at least one of the test organisms for
antibacterial, fungicidal, algicidal or herbicidal activities and only 64% of
those from soil did. Also they had isolated compounds belonged to different
structural groups: terpenoids, steroids, xanthones, chinones, phenols,
isocoumarines, benzopyranones, tetralones, cytochalasines and enniatines.