Exploration of Root-associated Bacteria from the Medicinal Plant Platycodon grandiflorum

• Published in: Microbes and Environments Vol. 34; no. 4; pp. 413 - 420
• Main Authors: Huang, Cong-Min, Chen, Wen-Ching, Lin, Shih-Han, Wang, Yu-Ning, Shen, Fo-Ting
• Format: Journal Article
• Language: English
• Published: Japan Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles 2019; Japan Science and Technology Agency; Japanese Society of Microbial Ecology (JSME)/Japanese Society of Soil Microbiology (JSSM)/Taiwan Society of Microbial Ecology (TSME)/Japanese Society of Plant Microbe Interactions (JSPMI)/Japanese Society for Extremophiles (JSE)
• Subjects: Acetic acid; Adaptation; Antioxidants - metabolism; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - metabolism; Bacterial Physiological Phenomena; Biomass; Carbon - metabolism; Culture media; DNA; Endophytes; Herbal medicine; Indoleacetic acid; Indoleacetic Acids - metabolism; Inoculation; medicinal plant; Medicinal plants; Microbiological strains; Niches; Nitrogen Fixation; Phosphates; Phosphates - metabolism; Phylogeny; plant constituent-hydrolyzing activities; Plant growth; plant growth promotion; Plant Roots - growth & development; Plant Roots - microbiology; Plants (botany); Plants, Medicinal - growth & development; Plants, Medicinal - microbiology; Platycodon - growth & development; Platycodon - microbiology; Platycodon grandiflorum; Rhizosphere; RNA, Ribosomal, 16S - genetics; root-associated bacteria; rRNA 16S; Seedlings; Seedlings - growth & development; Seedlings - microbiology; Strains (organisms); root-associated bacteria; medicinal plant; plant growth promotion; plant constituent-hydrolyzing activities; Platycodon grandiflorum
• ISSN: 1342-6311; 1347-4405
• DOI: 10.1264/jsme2.ME19030

The present study was performed to investigate root-associated bacteria from Platycodon grandiflorum, a medicinal plant commonly grown in East Asia. Isolates were obtained from the rhizosphere or root interior with various culture media, and phylogenetic analyses were performed based on their 16S rDNA sequences. In consideration of practical applications, traits related to plant growth promotion and niche adaptation were assessed in several endophytic strains with fewer biosafety concerns. The effects of a bacterial inoculation on seedling and mature plant growth were evaluated. Seventeen genera that encompassed more than 30 bacterial lineages were successfully retrieved from the roots, the majority of which have not been reported as P. grandiflorum-associated bacteria, particularly for non-negligible Proteobacteria. Although nitrogen-fixing or phosphate-solubilizing and indole acetic acid-producing activities were recorded in all of the strains selected, these strains were beneficial or detrimental to plant growth as evidenced by their influence on the length of seedlings and biomass of mature plants. Among the 4 endophytic Rhizobium species tested in the present study, the potentially novel Rhizobium sp. BF-E16, which was more compatible with the non-leguminous medicinal plant P. grandiflorum, was identified. Other than plant growth-promoting traits, characteristics such as plant constituent-hydrolyzing activities need to be taken into consideration and their roles clarified when investigating plant growth-promoting rhizobacteria.