Bioprospecting Beneficial Endophytic Bacterial Communities Associated With Rosmarinus Officinalis for Alleviating Plant Productivity

Abstract

The present study was aimed to isolate and identify root endophytic bacteria with multifunctional plant growth promoting (PGP) traits from medicinal plant Rosemarinus officinalis grown in the North-Western Himalayas. A total of 42 strains were isolated, exhibiting variable degrees of PGP traits, including P-solubilization (10-375 µg/ml), IAA (6-66 µg/ml), siderophore (32.37-301.48 %SU) production and antifungal activity in terms of percent growth inhibition (%GI) against Fusarium oxysporum (44.44-77.77 %GI), Fusarium graminiarum (48.88-71.42 %GI) and Rhizoctonia solani (44.44-77.7 %GI). 16S rDNA sequencing results showed lineage of these strains to 15 genera viz., Aneurinibacillus, Bacillus, Beijerinckia, Cedecea, Ensifer, Enterobacter, Kosakonia, Lactobacillus, Lysobacter, Oxynema, Pseudomonas, Pantoea, Paenibacillus, Pseudoxanthomonas and Serratia. The effect of 11 potential strains was selected for in vivo growth studies of R. officinalis. The results showed that the inoculation of Bacillus subtilis KU21, Pseudomonas aeruginosa SI12, and Cedecea lapagei KU14 significantly increased the physical growth parameters of plant over uninoculated control viz., number of lateral of branches (43.95-46.39 %), stem height (29.04-38.57 %), root length (32.31-37.14 %), shoot (34.76-40.91 %) and root biomass (62.89-70.70 %). Physiological characteristics such as total chlorophyll (30.41-30.96 %), phenol (14.43-24.55 %) and carotenoids (34.26-39.87 %) content, also showed a relative increase as compared to uninoculated control; furthermore, the macronutrients (NPK) contents of the plant as well as soil also showed an increase. The developed module may be recommended for sustainable production of R. officinalis in the North-Western Himalayan region without hampering the soil health and fertility.