phytopathogens. Endophytic microorganisms often produce diversity of antimi-
crobial bioactive compound comprising extracellular chitin or lytic enzymes
(glucanase and chitinase). The direct positive effects are production of phytohor-
mones such as IAA, GA, etc. non-symbiotic nitrogenfixation, and biofortification
of phosphorous and other essential nutrients include the trace elements to plants for
phytostimulation and to the soil for increasing fertilization power of soil (Burdman
et al. 2000 ). Innumerable compounds such as hydrocyanic acids (HCN), DAPG,
phenazines, pyrrolnitrin, enzymes and phytohormones to protect plant from toxic
effect of fungal pathogens are considered as the significant products to help
endophytes to be colonized in rhizosphere (Castro-Sowinski et al. 2007 ; Ramette
et al. 2011 ; Jousset et al. 2011 ). Besides, under iron-stress conditions in the soil and
on the surface plant, endophytes produce iron-chelator molecule called side-
rophores used to transport iron in a competitive way and deprived for the patho-
genic fungi as essential bioavailable element (Pedraza et al. 2007 ).
Many rhizosphere microorganisms can activate plant defence mechanisms and
induce a systemic response in plants. Bacteria are able to trigger signalling path-
ways to produce extracellular metabolites with higher toxicity for other microor-
ganism lead to destruction of higher pathogen, called induced systemic resistance
Fig. 7.1 Endophytic bacterial colonization in plants. Bacteria can enter a plant at several root
zones as indicated above. Endophytes can either remain at the site of entry (indicated inblue)or
move deeper inside or occupy the intercellular space of the cortex and xylem vessels (indicated in
green).Redandyellowrepresent rhizospheric bacteria which are unable to colonize inner plant
tissues
7 Role of Bacterial Endophytes in Plant Disease Control 137