Skip to main content
ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #319089
Title: Microbial communities in the rhizosphere and the root of lettuce as affected by contaminated irrigation water

Author
item ZHANG, YUPING - University Of Nebraska
item JEWETT, CHRISTIAN - University Of Nebraska
item Gilley, John
item BARTLETT-HUNT, SHANNON - University Of Nebraska
item SNOW, DANIEL - University Of Nebraska
item HODGES, LAURIE - University Of Nebraska

Submitted to: FEMS Microbiology Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2018
Publication Date: 9/1/2018
Citation: Zhang, Y., Jewett, C., Gilley, J.E., Bartlett-Hunt, S., Snow, D., Hodges, L. 2018. Microbial communities in the rhizosphere and the root of lettuce as affected by contaminated irrigation water. FEMS Microbiology Ecology. 94(9). https://doi.org/10.1093/femsec/fiy135.
DOI: https://doi.org/10.1093/femsec/fiy135

Interpretive Summary: Pathogens may contaminate food crops when reclaimed wastewater is used to irrigate croplands. However, little is known about how pathogens interact with the microbial communities associated with food crops. The objective of this study was to determine the effects of irrigation with recycled wastewater containing a pathogen (Salmonella) on the structure of the microbial communities in the soil and in the root of a leafy green vegetable (lettuce). The effects of different soil textures, lettuce cultivars, and harvest times on microbial communities were also examined. Results show that the microbes in the root originated primarily from microbes in the soil. The diversity of the bacterial community in roots was much lower than that in the soil. Based on diversity analyses, the Salmonella in irrigation water significantly altered the structure of the microbial community in the soil, but not in the root, likely by triggering the plant defense mechanisms. Soil texture played a more significant role than lettuce cultivar and harvest time in shaping the structure of the bacterial communities in the soil and the root.

Technical Abstract: Enteric pathogens may contaminate food crops when reclaimed wastewater is used to irrigate croplands. However, little is known about how external enteric pathogens interact with the microbial communities associated with food crops produced in the field. The objective of this study was to determine the effects of irrigation with recycled wastewater containing an enteric pathogen (Salmonella) on the structure of the microbial communities in the rhizosphere and in the root of a leafy green vegetable (lettuce). The effects of different soil textures, lettuce cultivars, and harvest times on microbial communities were also examined. A factorial design was used for the greenhouse experiment, and the microbial communities were characterized using Illumina sequencing of the 16S rRNA gene. Results show that the microbes in the root originated primarily from microbes in the rhizosphere. The alpha diversity of the bacterial community in roots was much lower than that in the rhizosphere. Based on beta diversity analyses, the Salmonella in irrigation water significantly altered the structure of the microbial community in the rhizosphere, but not in the root, likely through altering the composition of root exudates by triggering the plant defense mechanisms. Soil texture played a more significant role than lettuce cultivar and harvest time in shaping the structure of the bacterial communities in the rhizosphere and the root.