50 Khaled A. Selim, Mohamed M. S. Nagia and Dina E. El. Ghwas
occurring within herbaceous and photosynthetic tissues, class (3) endophytes
are present in fruits and flowers, as well as in inner bark and asymptomatic
wood (Tejesvi et al., 2005). Fungi with identical life recorded to class (3)
endophytes also found inside asymptomatic lichens and this case are called
‘endolichenic’ fungi (Arnold et al., 2003). It forms highly localized infections.
The variety of class (3) endophytes inside a host tissue or plant can be much
high (like > 20 species listed from a single tropical leaf (Arnold et al., 2003).
Merlin, 1922, while isolating and studying ectomycorrhizal fungi had
spotted a brown to blackish pigmented fungus related to terrestrial plant roots.
After that it was identified as class (4) endophytes (non-clavicipitaceous
endophytes) which are initially ascomycete’s fungi that are sterile or conidial
and that make melanized structure like as intra- and intercellular hyphae and
microsclerotia in the roots. These root-associated fungi and sterile called
“mycelium radicus astrovirens (MRA)”. The different type of class (4)
endophytes inside individual plants has not been enough evaluated. Also, it is
not confirmed to now if it increases fitness to hosts, rhizosphere competence
and mode of transmission or not. This class of endophytes is present in host
plants such as non-mycorrhizal from arctic, temperature zones, alpine, tropical
ecosystems, Antarctic and sub-alpine (Jumpponen, 2001).
6. BIOTECHNOLOGICAL APPLICATIONS OF ENDOPHYTES
Endophytes are producers of various types of bioactive secondary
metabolites containing derivatives of benzopyranones, phenolic acids,
alkaloids, flavonoids, terpenoids, xanthones, quinones, steroids, tetralones,
xanthones and others (Tan and Zou, 2001). These bioactive metabolites have
wide applications such as antibiotic, antiparasitics, agrochemicals, anticancer
agents, immunosuppressants and antioxidants (Strobel, 2003). In addition, they
play essential roles in nature.
6.1. In Agriculture Fields
About 300.000 plant species growing in different area on the earth are
becoming a host to one or more endophytes (Strobel and Daisy, 2003). Also,
the existence of big number of different endophytes plays important role on
ecosystems with a big difference, for example the temperature rainforests and
tropical area which, are found in Brazil containing about 20% of its