## 5 Role of Endophytic Bacteria in _Camelia sinensis_ Metabolism
PGPR application led to an enhancement in defense-related enzyme activity in tea leaves (phenyl alanine ammonia lyase, peroxidase, chitinase, and beta-1,3-glucanase). Total phenols also increased quantitatively. Thus, it becomes evident that PGPR application in the soil led to plants biopriming. _B. pumilus_ from tea's rhizosphere was in vitro and in vivo evaluated for its plant growth promoting and biocontrol activities [58]. This bacterium showed positive PGPR traits in vitro and inhibited tea root fungal pathogen growth, such as _P. hypobrunnea, F. lamaoensis, S. repens, S. scleroorum, and S. rdfsii_. Moreover, it enhanced phenolics accumulation and defense enzymes, and revealed a great ability to activate SAR in tea plants. Plant growth promoting ability of _B. megaterium_ isolated from tea bushes rhizosphere was tested on five varieties of tea in potted conditions and in the experimental field [49]. The results of this study showed an increase in height, emergence of new leaves, branches, and an increase in leaf numbers, as well as an increase in leaf dry mass following application of this bacterium. An increase in leaves and branch numbers was prominent after 12 months of application in field, but in potted plants a significant increase was obtained even after 2 months of application. A significant increase in phenolic compound accumulation and chlorophyll content was also stated in tea leaves. _B. megaterium_ was able to solubilize phosphate in vitro and in vivo. Following application  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Role** & **References** \\ \hline Increase defense-related enzymes & [47; 58; 59; 49] \\ Increase nitrogen fixation & [51; 53; 60] \\ Increase polyphenic amount & [47; 49; 58; 59] \\ Indole-3-acetic acid secretion & [57; 51; 52; 57; 52; 58; 59] \\ Inhibition of pathogen growth & [57; 59; 49; 51; 57; 58; 49; 51; 59] \\ Phosphate solubilizers & [47; 59; 51; 53; 58; 49; 51; 53; 59; 60] \\ Positive plant growth & [53; 47; 51; 52; 57; 58; 60; 49; 51; 53; 57; 58; 61; 59; 62; 63; 64; 65; 66; 67; 68; 69; 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 82; 84; 86; 87; 89; 88; 89; 91;  
of this bacterium, soil phosphatase activities were enhanced, soil phosphorus (P) content decreased, and root and leaf phosphate increased. Rooting induction from _C. sinensis_ cuttings by 2000 ppm indole-3-butyric acid (IBA) and PGPR treatments was done under controlled conditions [52]. The cuttings were sampled and treated with 7 bacteria strains, including _Bacillus_ species, _P. polymyxa_, _C. acidovorans_, and 2000 ppm IBA. All bacteria showed IAA producing capacity and higher rooting percentages compared with the control treatment. _B. megaterium_ and _S. marcescens_ were isolated from tea rhizosphere, enhanced tea varieties growth in the experimental field, as well as in nursery, as evidenced by increase in height and emergence of new leaves and branches [48]. Both _B. megaterium_ and _S. marcescens_ were able to solubilize phosphate in vitro and in vivo. Soil phosphate content decreased due to phosphate-solubilizing bacteria (PSB) activity, while root and leaf phosphate contents increased. Both acid and alkaline phosphatase activities in rhizosphere soil of all 5 varieties were enhanced following bacteria application. Thus, tea rhizosphere is a good habitat for PGPR strains represented by _Bacillus_ and _Pseudomonas_ species [60]. Several nitrogen fixers, phosphate solubilizers, and actinomycetes were isolated from tea rhizosphere soil. Microbial strains having plant growth promoting potential were screened in the pot trial. From these, 12 strains were subjected to greenhouse trial, and showed maximum gain in biomass weight of tea plants. This was followed by a field experiment with the same microbial strains as foliar spray to determine their effect on fresh leaf yield. [PERSON], [PERSON], [PERSON], and [PERSON] [2] isolated and identified _P. aeruginosa_ from _C. sinensis_ plantation soil of Barak Valley, Assam, India.