Culturable bacterial endophytes of Aconitum carmichaelii Debx. were diverse in phylogeny, plant growth promotion, and antifungal potential

Lan Zou; Qian Wang; Muyi Li; Siyu Wang; Kunhao Ye; Wei Dai; Jing Huang

doi:10.3389/fmicb.2023.1192932

Culturable bacterial endophytes of Aconitum carmichaelii Debx. were diverse in phylogeny, plant growth promotion, and antifungal potential

Front Microbiol. 2023 May 17:14:1192932. doi: 10.3389/fmicb.2023.1192932. eCollection 2023.

Authors

Lan Zou^#¹, Qian Wang^#¹, Muyi Li¹, Siyu Wang¹, Kunhao Ye², Wei Dai², Jing Huang¹

Affiliations

¹ School of Life Science and Engineering, Southwest University of Science and Technology, Miangyang, China.
² Institute of Traditional Chinese Medicinal Materials, Miangyang Academy of Agricultural Science, Mianyang, China.

^# Contributed equally.

Abstract

Medicinal plants harbor tremendously diverse bacterial endophytes that maintain plant growth and health. In the present study, a total of 124 culturable bacterial endophytes were isolated from healthy Aconitum carmichaelii Debx. plants. These strains were clustered into 10 genera based on full-length 16S rDNA sequences, among which Bacillus and Pseudomonas were the dominant genera. In addition, A. carmichaelii may capture 10 potential new bacterial species based on multi-locus sequence analysis of three housekeeping genes (gyrA, rpoB, and atpD). The majority of these bacterial endophytes exhibited plant growth-promoting ability through diverse actions including the production of either indole acetic acid and siderophore or hydrolytic enzymes (glucanase, cellulose, and protease) and solubilization of phosphate or potassium. A total of 20 strains inhibited hyphal growth of fungal pathogens Sclerotium rolfsii and Fusarium oxysporum in vitro on root slices of A. carmichaelii by the dual-culture method, among which Pseudomonas sp. SWUSTb-19 showed the best antagonistic activity. Field experiment confirmed that Pseudomonas sp. SWUSTb-19 significantly reduced the occurrence of southern blight and promoted plant biomass compared with non-inoculation treatment. The possible mode of actions for Pseudomonas sp. SWUSTb-19 to antagonize against S. rolfsii involved the production of glucanase, siderophore, lipopeptides, and antimicrobial volatile compounds. Altogether, this study revealed that A. carmichaelii harbored diverse plant growth-promoting bacterial endophytes, and Pseudomonas sp. SWUSTb-19 could be served as a potential biocontrol agent against southern blight.

Keywords: Sclerotium rolfsii; biological control; endophytic bacteria; genetic diversity; plant growth promotion.

Grants and funding

This research was supported by the Natural Science Foundation of Sichuan Province (No. 2022NSFSC1728), the Science and Technology Support Program of Sichuan Province (Nos. 2021NZZJ0025 and 2021YFN0068), the Doctoral Foundation of Southwest University of Science and Technology (No. 20zx7134), and the Innovation and Entrepreneurship Training Program for College Students of Sichuan Province (No. s202210619093).