48 Khaled A. Selim, Mohamed M. S. Nagia and Dina E. El. Ghwas
four special groups depending on six properties which are tissue(s) colonized,
plant colonization pattern, host range, plant biodiversity levels, ecological
functions and mechanism of transmission between host generations. Class (1)
is Clavicipitaceous endophytes while; non-Clavicipitaceous endophytes are
divided into three special groups class (2), class (3) and class (4) (Rodriguez et
al., 2009). We will summarize each class briefly:
European investigators in 19th century were the first who noted the class
(1) (Clavicipitaceous endophytes) was found in the seeds of Lolium linicolum,
Lolium arvense, Lolium remotum and Lolium temulentum (Vogl, 1898). After
that, Clay, 1988 demonstrated that they are defensive mutualists of host
grasses. From this time, investigations on endophyte natural history, ecology,
physiology and evolution has been followed (Schardl and Moon, 2003; Rao
et al., 2005 and Koulman et al., 2007). Usually these endophytes found within
plant shoots and make systemic intercellular infections. Colonized plants
always harbor one controlling fungal isolate/ genotype. According to Clay and
Schardl, 2002 there are three types of Clavicipitaceous endophytes extended
from pathogenic and symptomatic species (Type I) to mixed combination and
asymptomatic endophytes (Types II and III) respectively. The class (1)
endophytes are primarily transmitted vertically and horizontally on offspring
via seed infections (Saikkonen et al., 2002). Class (1) endophytes confer
drought tolerance, increase plant biomass and produced chemicals that toxic to
herbivory and animals (Clay, 1988). However, the importance of these fungi is
due to the host genotype, environmental conditions and host species (Faeth
and Sullivan, 2003).
On the other hand, class (2) (non-Clavicipitaceous endophytes) are highly
various, symbolizing a polyphyletic aggregation of primarily ascomycete's
fungi with diverse and always bad unknown ecological role. Non-
Clavicipitaceous endophytes have been isolated from everywhere of land plant
and from all terrestrial ecosystems, containing both biomes and ecosystems
ranging from the tundra to the tropics (Arnold and Lutzoni, 2007). The
capacity of lot of fungi to switch between free-living lifestyles and endophytic,
the prudence they supply into the evolution of different ecological modes in
fungi, their ecological roles, their potential applications and the scale of their
diversity are attractive to ecologists, mycologists, applied scientists and
physiologists (Vasiliauskas et al., 2007and Selosse et al., 2008). Non-
Clavicipitaceous endophytes can be distinguish into three classes depend on
mechanism of transmission between host generations, host colonization
patterns, ecological function and planta biodiversity levels as shown in Table
(2).