Role of Endophytic Bacteria in the Remobilization of Leaf Nitrogen Mediated by CsEGGT in Tea Plants (Camellia sinensis L.)

As an important economic plant, tea (Camellia sinensis) has a good economic value and significant health effects. Theanine is an important nitrogen reservoir, and its synthesis and degradation are considered important for nitrogen storage and remobilization in tea plants. Our previous research indicated that the endophyte CsE7 participates in the synthesis of theanine in tea plants. Here, the tracking test confirmed that CsE7 tended to be exposed to mild light and preferentially colonized mature tea leaves. CsE7 also participated in glutamine, theanine, and glutamic acid circulatory metabolism (Gln-Thea-Glu) and contributed to nitrogen remobilization, mediated by the γ-glutamyl-transpeptidase (CsEGGT) with hydrolase preference. The reisolation and inoculation of endophytes further verified their role in accelerating the remobilization of nitrogen, especially in the reuse of theanine and glutamine. This is the first report about the photoregulated endophytic colonization and the positive effect of endophytes on tea plants mediated and characterized by promoting leaf nitrogen remobilization.

Comparative Study of the Colonization of Chromolaena and Tobacco Plants by Bacteria safensis CS4 using Different Methods of Inoculation

BACKGROUND AND OBJECTIVES

This study entails the effectiveness of colonization of bacterial endophytes following inoculation of the cells in plants.

METHODOLOGY

Different methods of inoculation including seed immersion, root immersion and foliar spray were studied on Chromolaena odorata and Nicotiana tabacum for 10, 20 and 30 days. This was to ascertain the colonization ability of the endophytic strain amongst the two set of plants. The foliar parts of the plants were assessed post inoculation for the presence of the bacteria strain, followed by the growth parameters in the plant. Significant differences at p<0.05 of colonization were established by the different inoculation methods.

RESULTS

Foliar spray demonstrated the highest colonization in both Chromolaena and tobacco plants followed by root immersion. Leaf inoculation in tobacco plant demonstrated a positive colonization which is not significant. However, seed inoculation provided colonization in Chromolaena plant at 10, 20 and 30 days post inoculation at a frequency lower than that of tobacco. With root immersion in Chromolaena, there was colonization at 10 days post inoculation, no colonization at 20 days post inoculation, but colonization re-appeared at 30 days (PI). Growth index measured demonstrated a positive relationship between the inoculation of the endophyte and the growth parameters which included stem length and germination rate.

CONCLUSION

This study, therefore, showed that the bacteria strain B. safensis CS4 can effectively be horizontally transferred into tobacco and Chromolaena plants using different methods. Foliar spraying demonstrated the optimal colonization of the strain in the plant leaves.