Pseudomonas aeruginosa Ld-08 isolated from Lilium davidii exhibits antifungal and growth-promoting properties

A plant growth-promoting and antifungal endophytic bacteria designated as Ld-08 isolated from the bulbs of Lilium davidii was identified as Pseudomonas aeruginosa based on phenotypic, microscopic, and 16S rRNA gene sequence analysis. Ld-08 exhibited antifungal effects against Fusarium oxysporum, Botrytis cinerea, Botryosphaeria dothidea, and Fusarium fujikuroi. Ld-08 showed the highest growth inhibition, i.e., 83.82±4.76% against B. dothidea followed by 74.12±3.87%, 67.56±3.35%, and 63.67±3.39% against F. fujikuroi, B. cinerea, and F. oxysporum, respectively. The ethyl acetate fraction of Ld-08 revealed the presence of several bioactive secondary metabolites. Prominent compounds were quinolones; 3,9-dimethoxypterocarpan; cascaroside B; dehydroabietylamine; epiandrosterone; nocodazole; oxolinic acid; pyochelin; rhodotulic acid; 9,12-octadecadienoic acid; di-peptides; tri-peptides; ursodiol, and venlafaxine. The strain Ld-08 showed organic acids, ACC deaminase, phosphate solubilization, IAA, and siderophore. The sterilized bulbs of a Lilium variety, inoculated with Ld-08, were further studied for plant growth-promoting traits. The inoculated plants showed improved growth than the control plants. Importantly, some growth parameters such as plant height, leaf length, bulb weight, and root length were significantly (P ≤0.05) increased in the inoculated plants than in the control un-inoculated plants. Further investigations are required to explore the potential of this strain to be used as a plant growth-promoting and biocontrol agent in sustainable agriculture.