42 Khaled A. Selim, Mohamed M. S. Nagia and Dina E. El. Ghwas
2) The endophytes fungi or bacteria are living a part or all of their life
cycle and causing asymptomatic infections inside plant tissues
(Wilson, 1995).Both of these definitions (but not de Bary’s) include endophytes of roots,
which have been found in everywhere (Schulz et al., 2006). In addation, the
final stages of infections by pathogens are inclusive in theses identification,
but excluded from them mycorrhizal fungi because they are partly external and
often symptomatic (Saikkonen et al., 1998). The term endophytes are often
joined with alternate to refer to a specific host, the type of tissue occupied or a
taxonomic group of hosts (e.g., bark endophytes and systemic grass
endophytes). This mean that, the identification of endophytes are depend
primarily on location rather than symbiotic interaction type. Recent
applications of the terms of endophytes never consistent and not accepted by
all researchers but in 1991 Petrini showed an identification of endophytes that
has been accepted widely. Endophytic are important group of microorganisms
linked with different organs and tissues of aquatic and terrestrial plant, whose
infections are unclear and the infected host tissue are symptomless (Stone
et al., 2000) rather than parasites which caused disease and reduce fitness of
their host plant. Therefore, the defined endophytes are wide enough to contain
any microorganisms (cyanobacteria, fungi and bacteria) that living in the
internal tissues of plants. On the other hand, the word endophyte for grass
hosts (primarily Poaceae) was specially used for this type of systemic
nonpathogenic symbiosis. These grasses endophyte support their hosts with
many advantage like protection against herbivory and pathogens (Saikkonen
et al., 1998). Taxonomically theses fungi begin related to Neotyphodium
anamorphs of Balansiae (Clavicipitaceae); they colonize root tissues and culm
of species of leaf and cool season grasses. Host and fungus are working
together as a single organism and sporulation on the host is completely
suppressed. Also, endophytes of Festuca, Lolium and other genera of grasses
which derived from Epichloë species are inter specific hybrid strains and lead
to partial or completely host sterility (Moon et al., 2000).
2. DISTRIBUTION OF ENDOPHYTIC FUNGI IN NATURE
In the last two decades, researchers proved that, endophytic fungi colonize
land plants everywhere on the earth. Endophytes are isolated from plants
growing in in tropical temperature, boreal forest, aquatic and extreme arctic