Mutualistic Outcomes Across Plant Populations, Microbes, and Environments in the Duckweed Lemna minor

• Published in: Microbial ecology 2020-08, Vol.80 (2), p.384-397
• Main Authors: O’Brien, Anna M., Laurich, Jason, Lash, Emma, Frederickson, Megan E.
• Format: Article
• Language: English
• Subjects: Abiotic factors; Aggregation; Aquatic habitats; Aquatic plants; Araceae - drug effects; Araceae - genetics; Araceae - growth & development; Araceae - microbiology; Bacteria - growth & development; Biomedical and Life Sciences; Bioremediation; Contaminants; Duckweed; Ecology; Environmental stress; Factorial experiments; Floating plants; Freshwater plants; Genetic Fitness; Genotype; Genotype & phenotype; Genotypes; Geoecology/Natural Processes; Host Microbial Interactions; Lemna minor; Life Sciences; Microbial activity; Microbial Ecology; Microbiology; Microbiomes; Microbiota; Microbiota - physiology; Microorganisms; Nature Conservation; Phenotypes; Phytoremediation; Plant growth; PLANT MICROBE INTERACTIONS; Plant population; Plant populations; Populations; Symbiosis; Urban areas; Water Pollutants, Chemical - adverse effects; Water pollution; Water Quality/Water Pollution; Zinc; Zinc - adverse effects
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-019-01452-1

The picture emerging from the rapidly growing literature on host-associated microbiota is that host traits and fitness often depend on interactive effects of host genotype, microbiota, and abiotic environment. However, testing interactive effects typically requires large, multi-factorial experiments and thus remains challenging in many systems. Furthermore, most studies of plant microbiomes focus on terrestrial hosts and microbes. Aquatic habitats may confer unique properties to microbiomes. We grew different populations of duckweed (Lemna minor), a floating aquatic plant, in three microbial treatments (adding no, “home”, or “away” microbes) at two levels of zinc, a common water contaminant in urban areas, and measured both plant and microbial performance. Thus, we simultaneously manipulated plant source population, microbial community, and abiotic environment. We found strong effects of plant source, microbial treatment, and zinc on duckweed and microbial growth, with significant variation among duckweed genotypes and microbial communities. However, we found little evidence of interactive effects: zinc did not alter effects of host genotype or microbial community, and host genotype did not alter effects of microbial communities. Despite strong positive correlations between duckweed and microbe growth, zinc consistently decreased plant growth, but increased microbial growth. Furthermore, as in recent studies of terrestrial plants, microbial interactions altered a duckweed phenotype (frond aggregation). Our results suggest that duckweed source population, associated microbiome, and contaminant environment should all be considered for duckweed applications, such as phytoremediation. Lastly, we propose that duckweed microbes offer a robust experimental system for study of host–microbiota interactions under a range of environmental stresses.