Title: Microbial abundance, composition, and function in nectar are shaped by flower visitor identity

Journal Article · · FEMS Microbiology Ecology
ORCiD logo [1];  [2];  [3];  [2];  [3]
  1. San Diego State Univ., CA (United States); Univ. of California, Davis, CA (United States); Stanford Univ., CA (United States)
  2. San Diego State Univ., CA (United States)
  3. Univ. of California, Davis, CA (United States)

Microbial dispersal is essential for establishment in new habitats, but the role of vector identity is poorly understood in community assembly and function. In this study, we compared microbial assembly and function in floral nectar visited by legitimate pollinators (hummingbirds) and nectar robbers (carpenter bees). We assessed effects of visitation on the abundance and composition of culturable bacteria and fungi and their taxonomy and function using shotgun metagenomics and nectar chemistry. We also compared metagenome-assembled genomes (MAGs) of Acinetobacter, a common and highly abundant nectar bacterium, among visitor treatments. Visitation increased microbial abundance, but robbing resulted in 10× higher microbial abundance than pollination. Microbial communities differed among visitor treatments: robbed flowers were characterized by predominant nectar specialists within Acetobacteraceae and Metschnikowiaceae, with a concurrent loss of rare taxa, and these resulting communities harbored genes relating to osmotic stress, saccharide metabolism and specialized transporters. Gene differences were mirrored in function: robbed nectar contained a higher percentage of monosaccharides. Draft genomes of Acinetobacter revealed distinct amino acid and saccharide utilization pathways in strains isolated from robbed versus pollinated flowers. Our results suggest an unrecognized cost of nectar robbing for pollination and distinct effects of visitor type on interactions between plants and pollinators. Overall, these results suggest vector identity is an underappreciated factor structuring microbial community assembly and function.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDA; USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1775029
Report Number(s):
LLNL-JRNL-814184; 1022619
Journal Information:
FEMS Microbiology Ecology, Journal Name: FEMS Microbiology Ecology Journal Issue: 3 Vol. 96; ISSN 0168-6496
Publisher:
Federation of European Microbiology SocietiesCopyright Statement
Country of Publication:
United States
Language:
English

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