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Functional relationships between aboveground and belowground spinach (Spinacia oleracea L., cv. Racoon) microbiomes
A Mark Ibekwe1, Selda Ors2, Jorge F S Ferreira1
1US Salinity Laboratory, USDA-ARS, 450 W. Big Springs Rd., Riverside, CA 92507, USA.
The Science of the Total Environment
|February 20, 2020
Summary
Salinity and drought impact spinach microbiomes differently above and below ground, altering bacterial communities and functions across seasons. This research highlights key microbial pathways affected by these environmental stressors.
Area of Science:
- Agricultural Science
- Microbiology
- Environmental Science
Background:
- Salinity poses a significant threat to agriculture, particularly in arid and semiarid regions.
- Seasonal variations in salinity and drought can influence plant-associated microbial communities (microbiomes).
- Limited research exists on the combined effects of salinity and drought on plant microbiomes and their functional roles.
Purpose of the Study:
- To investigate the impact of salinity and drought on spinach (Spinacia oleracea L.) above- and belowground microbiomes.
- To analyze seasonal shifts in bacterial community composition and diversity.
- To assess potential functional consequences for these microbiomes using 16S V4 rRNA gene profiles and Piphillin analysis.
Main Methods:
- Spinach was cultivated in sand tanks under varying salinity and water availability conditions across three seasonal repetitions.
- Bacterial communities were analyzed in soil, rhizosphere, and phyllosphere samples using 16S V4 rRNA gene sequencing.
- Functional gene abundances and pathways were inferred using Piphillin.
Main Results:
- Salinity significantly altered root microbiome beta-diversity but not the relative abundance of microbial taxa.
- Proteobacteria, Cyanobacteria, and Bacteroidetes were dominant in the rhizosphere; Proteobacteria, Bacteroidetes, and Actinobacteria in soil; and Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria in the phyllosphere.
- Functional analysis revealed enriched pathways in the rhizosphere, including monoterpenoid biosynthesis, and indicated differential impacts of salinity and drought on above- and belowground microbiomes.
Conclusions:
- Salinity and drought exert distinct influences on spinach's above- and belowground microbiomes.
- Seasonal changes significantly affect bacterial community structure and function.
- Rhizosphere bacteria exhibit high functional gene abundances, with salinity and drought modulating these profiles.
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