techniques could be imprecise in detecting endophytic population (Bent and
Chanway 2002 ). Pw-2R colonized both stem vesicular tissues and root cortical
tissues in a 4-month-old spruce seedling, thus establishing its endophytic nature in
spruce (Shishido et al. 1999 ). Earlier studies have confirmed the presence of bac-
terial endophytes in hybrid spruce growing in regions of BC, Canada, and their role
in growth promotion of spruce seedlings both in greenhouse andfield conditions.
Most bacterial endophytes are isolated from either root or stem tissues of plants but
Cankar et al. ( 2005 ) reported the presence of bacterial endophytes in Norway spruce
(Picea abiesL. Karst) seeds. In a previous study, this group confirmed the presence
of PGPR bacteria in the rhizosphere of Norway spruce trees and characterized their
beneficial effects (Geric et al. 2000 ). Fresh seeds from four different trees of
Norway spruce growing in different locations within a 36 km
2
area in Pokljuka,
Slovenia (1200–1400 m elevation) revealed the presence of bacterial endophytes in
seed coat, endosperm, and embryonic tissue. Most endophytes belonged to genera
Pseudomonas and Rahnella, which are well known for their plant
growth-promoting and N-fixing properties (Cankar et al. 2005 ).
6.3.4 Pseudotsuga, Quercus, Salix, and Thuja
The presence of bacterial endophytes has also been reported in other coniferous
trees like Douglas-fir(Pseudotsuga menziesii) and western red cedar (Thuja
Plicata) and deciduous trees like oak (QuercusL.) and willow (SalixL.). Bal et al.
( 2012 ) reported the isolation of endophytic bacteria from stem and needles tissues
of western red cedar seedlings (2–4 years old) and trees (>20 years old) growing at
a site near Boston Bar, BC, Canada (49°50′N, 121°31′W, elevation 600 m; moist
warm Interior Douglas-fir zone (IDFmw)). Endophytic bacterial strains were
identified as belonging to the genera Arthrobacter, Bacillus, Burkholderia,
Paenibacillus,andPseudomonas. One of the strainsPaenibacillus amylolyticus
C3b was found to produce 241 pmols C 2 H 4 mL−^1 h−^1 of ethylene in the acetylene
reduction assay and was able to grow on N-free growth medium, thereby estab-
lishing its diazotrophic ability (Bal et al. 2012 ). Lodgepole pine bacterial endo-
phyte,P. polymyxaP2b-2R (Bal et al. 2012 ), was also tested for its ability to
colonize and promote the growth of western red cedar seedlings. Bal and Chanway
(2012b) reported that P2b-2R can colonize rhizosphere of cedar with a population
size of 10
5
cfu/g root but cannot colonize the internal tissues. They also reported
that P2b-2R inoculation increased the foliar N content by 33% as compared to the
controls 27 weeks after inoculation. Cedar seedlings inoculated with P2b-2R
derived 56% and 23% of N directly from the atmosphere 27 and 35 weeks after
inoculation, respectively (Table6.2). These results were later confirmed by Anand
and Chanway (2013b). Apart from deriving significant amounts of N from the
atmosphere, western red cedar seedlings accumulated 45% greater shoot biomass
than control seedlings 13 months after inoculation (Anand and Chanway2013b).
Another aim of this study was to investigate the endophytic colonization of cedar
6 Beneficial Effects of Bacterial Endophytes... 125