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Title: Response of plant associated microbiome to plant-root colonization by exogenous bacterial endophyte in perennial crops

Author
item Yurgel, Svetlana
item AJEETHAN, NIVETHIKA - Dalhousie University
item SMERTENKO, ANDREI - Washington State University

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2022
Publication Date: 4/5/2022
Citation: Yurgel, S., Ajeethan, N., Smertenko, A. 2022. Response of plant associated microbiome to plant-root colonization by exogenous bacterial endophyte in perennial crops. Frontiers in Microbiology. Volume 12, Article 863946. https://doi.org/10.3389/fmicb.2022.863946.
DOI: https://doi.org/10.3389/fmicb.2022.863946

Interpretive Summary: Plant growth promoting microorganisms (PGPM) can be used as biofertilizers or biocontrol agents (BCA) to reduce the use of fertilizers and pesticides in agricultural systems. The efficiency of these BCA depends not only on the ability of the microorganism to promote plant growth but also on their ability to establish symbiosis with the plant and the stability of the introduced microbes in plant tissue over extended growth periods. In this study we used a single bacterial inoculation to monitor its effect on the soil and plant-associated microorganisms over a one-year period. We determined that that while bacterial inoculations might have a short-term effect on the composition for root-associated bacteria, they can boost cooperation between PGPM inside the plant roots. We demonstrated that this cooperation could exist for the extended period of time. Therefore, the application of BCA might promote the establishment of symbiosis between naturally accruing PGPM and perennial crops and provide additional benefits for plant health and production.

Technical Abstract: The application of bacterial inoculums for improving plant growth and production is an important component of sustainable agriculture. However, the efficiency of inoculums for perennial crops depends on the stability of the introduced endophytes in host-plant tissue over extended growth periods. In this study we monitored the effect of a single bacterial strain inoculation on the diversity and structure of soil and plant-associated microbiomes over one-year period. An endophyte isolated from Vaccinium angustifolium (wild blueberry) roots and annotated as Rhizobiales was used for inoculation of 1 year-old Lonicera caerulea (Haskap) plants. A significant level of bacterial community perturbation was detected after 3 months post-inoculation in plant root and soil, while rhizosphere community was not significantly affected. About 14% of soil and 23% of root associated community variation correlated with application of the inoculant, which was accompanied by an increased cooperation between taxa belonging to Proteobacteria and Actinobacteriota phyla and decreased cooperation between Firmicutes in plant roots. A decrease in bacterial Shannon diversity was detected in roots of inoculated plants. Additionally, the families of Rhizobiaceae and Enterobacteriaceae were overrepresented in the roots of inoculated plants relative to the non-inoculated control. After a year of field growth, no differences in bacterial community composition as well as alpha- and beta- diversities were detected between bacterial communities from inoculated and non-inoculated roots. However the introduction of RF67 trigger an interaction within root associated microbiome, which was detected 3 month and 1 year post inoculation. These findings suggest that while exogenous endophytes might have a short-term effect on the root microbiome structure and composition, they can boost cooperation between plant-growth promoting endophytes, which can exist for the extended period of time.