Pseudomonas, Bacillus, XanthomonasandErwiniaare growth promontory as well
as inhibit various diseases causing phytopathogen in plants. Endophytes also pro-
mote plant growth by enhance phosphate solubilisation (Verma et al. 2001 ;
Wakelin et al. 2004 ) IAA production (Lee et al. 2004 ) siderophore production
(Costa and Loper 1994 ) and facilitating vitamins to plants (Pirttila et al. 2004 ). The
other physiological adjustments include osmotic, stamal regulation and morpho-
logical modifications such as alteration in root morphology enhanced immobi-
lization of minerals nutrients along with nitrogen accumulation and its metabolism
(Compant et al.2005a, b).
Free-living and endophytic bacteria use similar mechanism to enhance plant
growth and development beside, being different in their efficiency for their bene-
ficial effect. Plant Growth-Promoting Rhizobacteria (PGPR) are able to colonize in
the root vicinity thereby promoting plant growth and increase yield. Phytohormones
such as IAA contributes for root abundance and hence, provide enhanced minerals
and nutrient uptake to the plant. Production of diffusible and non-diffusable anti-
fungal metabolites assists in the biocontrol soil-borne fungi. The detailed mecha-
nism of action of endophytic bacteria is given below (Fig.7.2).
Fig. 7.2 Mechanism of action of endophytic bacteria
142 A. Muthukumar et al.