Endophytic bacteria associated with critically endangered medicinal plant Trillium govanianum (Wall ex. Royle) and their potential in soil nutrition alleviation

Abstract

Trillium govaniaunm is a critically endangered medicinal plant commonly known as ‘Nag Chhatri’ that grows mainly in the dry temperate zone of western Himalayas India. Here, in the present study, T. govanianum plants have been explored to isolate and identify bacterial endophytes with plant growth promoting potential and to evaluate their effects on soil biochemical property under field conditions. In total, 107 endophytic bacteria have been isolated from T. govanianum which were then tested for their in vitro plant growth promoting activity. Twenty two bacterial strains which showed all PGP traits were selected for evaluating their enzymatic and drought tolerating potential. The best P-solubilisation and IAA production 92.56 ± 2.29 μg/ml, and 62.74 ± 0.58 μg/ml were recorded by strain Ar13 respectively" in this way, the strain Ar13 demonstrated the best P-solubilisation and IAA production, whereas Ms5 produced the highest siderophore production i.e. 94.86 ± 2.02%. The maximum protease (18.00 ± 0.11 mm) was shown by strain Ms5 whereas, Ar13 showed the highest cellulase (20.00 ± 0.41 mm), chitinase (22 ± .02 mm) and ACC deaminase (48.84 ± ± 0.17 µM ά-KB mg−1h − 1). In total three bacterial isolates were further selected for further studies and identified as Pantoea spp. Ar13, Microbacterium spp. Ar17 and Pseudomonas spp. Ms5 by 16S rRNA gene sequencing. Furthermore, these three selected bacterial isolates were utilized individually and in consortia for the field application for consecutive two years. The findings unveiled a notably enhancement of micronutrients in all plants subjected to bacterial strains, when compared to the control group. The consortium of endophytes recorded significantly higher total soil organic carbon (2.58 ± 0.03%), electric conductivity (0.21 ± 0.01 dsm-1), and soil nutrients like available N (418.75 ± 1.42 kg ha-1), P (36.05 ± 0.12 kg ha-1), K (291.23 ± 0.99 kg ha-1) content and soil enzymes like dehydrogenase, phosphatase and microbial population. To our knowledge, this is the very first report of its kind of the isolation of endophytic bacterial strains from T. govanianum and microorganisms that can be utilized in future applications for agricultural sustainability.