Rhizosphere bacteriome assemblage following initial fluctuations is delayed with nitrogen additions in tomato seedlings

Authors: DIXON, MARY - Colorado State University; ROHRBAUGH, CARLEY - Colorado State University; Manter, Daniel; Delgado, Jorge; VIVANCO, JORGE - Colorado State University

Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2024
Publication Date: 11/27/2024
Citation: Dixon, M.M., Rohrbaugh, C., Manter, D.K., Delgado, J.A., Vivanco, J.M. 2024. Rhizosphere bacteriome assemblage following initial fluctuations is delayed with nitrogen additions in tomato seedlings. Biology and Fertility of Soils. 61:233-246. https://doi.org/10.1007/s00374-024-01882-1.
DOI: https://doi.org/10.1007/s00374-024-01882-1

Interpretive Summary: Microbial communities respond to a variety of disturbances such as planting. In this study, we explored weekly changes in the soil microbial community following planting under different N rates and types (urea vs slow-release urea). In the control treatment, microbial communities stabilized two weeks after planting; whereas, when N fertilizers were applied, bacteria continued to fluctuate through the fifth week. This study shows that although fertilizer can influence bacterial communities the changes are not long lasting and depend upon the rate of fertilizer applied.

Technical Abstract: Little is known about how seedlings sense new soil environments and how the rhizosphere microbiome changes accordingly. It is important to elucidate these changes to better understand the feedbacks that contribute to nutrient cycling and plant fitness. Here, we explored how the tomato rhizosphere microbiome developed weekly throughout the vegetative developmental stage and with variable additions of nitrogen (N) fertilizers. Bacterial communities expressing diverse functions highly fluctuated in the first and second week after the planting of seedlings, and these fluctuations diminished progressively after the third week. Bacteria capable of biocontrol stabilized after the fourth week, while those involved in nutrient cycling continued to change in abundance week-to-week. Thus, bacterial specialization may be concomitant with microbiome stabilization. When N fertilizers were applied, bacteria with diverse functions continued to fluctuate through the fifth week. However, regardless of fertilization, rhizosphere bacterial communities stabilized and were closely related by the sixth week than the early weeks of vegetative development. Ultimately, we conclude that it may take two weeks for plants roots to select for specific root-associated bacteria, but when N is applied, this period is extended. This study showcases the dynamics of rhizosphere assemblage and how this process is affected by N additions.