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Rering CC, Rudolph AB, Li QB, Read QD, Muñoz PR, Ternest JJ, Hunter CT. A quantitative survey of the blueberry (Vaccinium spp.) culturable nectar microbiome: variation between cultivars, locations, and farm management approaches. FEMS Microbiol Ecol 2024; 100:fiae020. [PMID: 38366934 PMCID: PMC10903978 DOI: 10.1093/femsec/fiae020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 01/25/2024] [Accepted: 02/15/2024] [Indexed: 02/19/2024] Open
Abstract
Microbes in floral nectar can impact both their host plants and floral visitors, yet little is known about the nectar microbiome of most pollinator-dependent crops. In this study, we examined the abundance and composition of the fungi and bacteria inhabiting Vaccinium spp. nectar, as well as nectar volume and sugar concentrations. We compared wild V. myrsinites with two field-grown V. corymbosum cultivars collected from two organic and two conventional farms. Differences in nectar traits and microbiomes were identified between V. corymbosum cultivars but not Vaccinium species. The microbiome of cultivated plants also varied greatly between farms, whereas management regime had only subtle effects, with higher fungal populations detected under organic management. Nectars were hexose-dominant, and high cell densities were correlated with reduced nectar sugar concentrations. Bacteria were more common than fungi in blueberry nectar, although both were frequently detected and co-occurred more often than would be predicted by chance. "Cosmopolitan" blueberry nectar microbes that were isolated in all plants, including Rosenbergiella sp. and Symmetrospora symmetrica, were identified. This study provides the first systematic report of the blueberry nectar microbiome, which may have important implications for pollinator and crop health.
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Affiliation(s)
- Caitlin C Rering
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr, Gainesville, FL 32608, United States
| | - Arthur B Rudolph
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr, Gainesville, FL 32608, United States
| | - Qin-Bao Li
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr, Gainesville, FL 32608, United States
| | - Quentin D Read
- Agricultural Research Service, Southeast Area, United States Department of Agriculture, 840 Oval Drive, Raleigh, NC 27606, United States
| | - Patricio R Muñoz
- Horticultural Sciences Department, University of Florida, 2550 Hull Rd, Gainesville, FL 32611, United States
| | - John J Ternest
- Department of Entomology and Nematology, University of Florida, 1881 Natural Area Dr, Gainesville, FL 32611, United States
| | - Charles T Hunter
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr, Gainesville, FL 32608, United States
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2
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Gaube P, Marchenko P, Müller C, Schweiger R, Tenhaken R, Keller A, Junker RR. Inter- and intraspecific phytochemical variation correlate with epiphytic flower and leaf bacterial communities. Environ Microbiol 2023; 25:1624-1643. [PMID: 37011905 DOI: 10.1111/1462-2920.16382] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/24/2023] [Indexed: 04/05/2023]
Abstract
Microbes associated with flowers and leaves affect plant health and fitness and modify the chemical phenotypes of plants with consequences for interactions of plants with their environment. However, the drivers of bacterial communities colonizing above-ground parts of grassland plants in the field remain largely unknown. We therefore examined the relationships between phytochemistry and the epiphytic bacterial community composition of flowers and leaves of Ranunculus acris and Trifolium pratense. On 252 plant individuals, we characterized primary and specialized metabolites, that is, surface sugars, volatile organic compounds (VOCs), and metabolic fingerprints, as well as epiphytic flower and leaf bacterial communities. The genomic potential of bacterial colonizers concerning metabolic capacities was assessed using bacterial reference genomes. Phytochemical composition displayed pronounced variation within and between plant species and organs, which explained part of the variation in bacterial community composition. Correlation network analysis suggests strain-specific correlations with metabolites. Analysis of bacterial reference genomes revealed taxon-specific metabolic capabilities that corresponded with genes involved in glycolysis and adaptation to osmotic stress. Our results show relationships between phytochemistry and the flower and leaf bacterial microbiomes suggesting that plants provide chemical niches for distinct bacterial communities. In turn, bacteria may induce alterations in the plants' chemical phenotype. Thus, our study may stimulate further research on the mechanisms of trait-based community assembly in epiphytic bacteria.
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Affiliation(s)
- Paul Gaube
- Department of Bioinformatics, University of Würzburg, D-97074, Würzburg, Germany
- Center for Computational and Theoretical Biology, University of Würzburg, D-97074, Würzburg, Germany
| | - Polina Marchenko
- Department of Environment and Biodiversity, University of Salzburg, A-5020, Salzburg, Austria
| | - Caroline Müller
- Department of Chemical Ecology, Bielefeld University, D-33615, Bielefeld, Germany
| | - Rabea Schweiger
- Department of Chemical Ecology, Bielefeld University, D-33615, Bielefeld, Germany
| | - Raimund Tenhaken
- Department of Environment and Biodiversity, University of Salzburg, A-5020, Salzburg, Austria
| | - Alexander Keller
- Cellular and Organismic Networks, Center for Organismic Adaptation (CORA), Faculty of Biology, LMU Munich, Planegg-Martinsried, D-82152, Germany
| | - Robert R Junker
- Department of Environment and Biodiversity, University of Salzburg, A-5020, Salzburg, Austria
- Evolutionary Ecology of Plants, Department of Biology, University of Marburg, D-35032, Marburg, Germany
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3
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Hietaranta E, Juottonen H, Kytöviita MM. Honeybees affect floral microbiome composition in a central food source for wild pollinators in boreal ecosystems. Oecologia 2023; 201:59-72. [PMID: 36434466 DOI: 10.1007/s00442-022-05285-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 11/07/2022] [Indexed: 11/26/2022]
Abstract
Basic knowledge on dispersal of microbes in pollinator networks is essential for plant, insect, and microbial ecology. Thorough understanding of the ecological consequences of honeybee farming on these complex plant-pollinator-microbe interactions is a prerequisite for sustainable honeybee keeping. Most research on plant-pollinator-microbe interactions have focused on temperate agricultural systems. Therefore, information on a wild plant that is a seasonal bottleneck for pollinators in cold climate such as Salix phylicifolia is of specific importance. We investigated how floral visitation by insects influences the community structure of bacteria and fungi in Salix phylicifolia inflorescences under natural conditions. Insect visitors were experimentally excluded with net bags. We analyzed the microbiome and measured pollen removal in open and bagged inflorescences in sites where honeybees were foraging and in sites without honeybees. Site and plant individual explained most of the variation in floral microbial communities. Insect visitation and honeybees had a smaller but significant effect on the community composition of microbes. Honeybees had a specific effect on the inflorescence microbiome and, e.g., increased the relative abundance of operational taxonomic units (OTUs) from the bacterial order Lactobacillales. Site had a significant effect on the amount of pollen removed from inflorescences but this was not due to honeybees. Insect visitors increased bacterial and especially fungal OTU richness in the inflorescences. Pollinator visits explained 38% variation in fungal richness, but only 10% in bacterial richness. Our work shows that honeybee farming affects the floral microbiome in a wild plant in rural boreal ecosystems.
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Affiliation(s)
- Elsi Hietaranta
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland.
| | - Heli Juottonen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland
| | - Minna-Maarit Kytöviita
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland
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4
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Russell KA, McFrederick QS. Floral nectar microbial communities exhibit seasonal shifts associated with extreme heat: Potential implications for climate change and plant-pollinator interactions. Front Microbiol 2022; 13:931291. [PMID: 36090097 PMCID: PMC9453676 DOI: 10.3389/fmicb.2022.931291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/25/2022] [Indexed: 11/13/2022] Open
Abstract
Floral nectar contains vital nutrients for pollinators, including sugars, amino acids, proteins, and secondary compounds. As pollinators forage, they inoculate nectar with bacteria and fungi. These microbes can colonize nectaries and alter nectar properties, including volume and chemistry. Abiotic factors, such as temperature, can influence microbial community structure and nectar traits. Considering current climate change conditions, studying the effects of increased temperature on ecosystem processes like pollination is ever more important. In a manipulative field experiment, we used a passive-heating technique to increase the ambient temperature of a California native plant, Penstemon heterophyllus, to test the hypothesis that temperatures elevated an average of 0.5°C will affect nectar properties and nectar-inhabiting microbial communities. We found that passive-heat treatment did not affect nectar properties or microbial communities. Penstemon heterophyllus fruit set also was not affected by passive-heat treatments, and neither was capsule mass, however plants subjected to heat treatments produced significantly more seeds than control. Although we conducted pollinator surveys, no pollinators were recorded for the duration of our experiment. A naturally occurring extreme temperature event did, however, have large effects on nectar sugars and nectar-inhabiting microbial communities. The initially dominant Lactobacillus sp. was replaced by Sediminibacterium, while Mesorhizobium, and Acinetobacter persisted suggesting that extreme temperatures can interrupt nectar microbiome community assembly. Our study indicates that the quality and attractiveness of nectar under climate change conditions could have implications on plant-pollinator interactions.
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5
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Adler LS, Irwin RE, McArt SH, Vannette RL. Floral traits affecting the transmission of beneficial and pathogenic pollinator-associated microbes. CURRENT OPINION IN INSECT SCIENCE 2021; 44:1-7. [PMID: 32866657 PMCID: PMC7914268 DOI: 10.1016/j.cois.2020.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 05/22/2023]
Abstract
Flowers provide resources for pollinators, and can also be transmission venues for beneficial or pathogenic pollinator-associated microbes. Floral traits could mediate transmission similarly for beneficial and pathogenic microbes, although some beneficial microbes can grow in flowers while pathogenic microbes may only survive until acquired by a new host. In spite of conceptual similarities, research on beneficial and pathogenic pollinator-associated microbes has progressed mostly independently. Recent advances demonstrate that floral traits are associated with transmission of beneficial and pathogenic microbes, with consequences for pollinator populations and communities. However, there is a near-absence of experimental manipulations of floral traits to determine causal effects on transmission, and a need to understand how floral, microbe and host traits interact to mediate transmission.
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Affiliation(s)
- Lynn S Adler
- Department of Biology, University of Massachusetts, 221 Morrill Science Center, 611 N. Pleasant St., Amherst MA 01002 USA.
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, 127 David Clark Labs, 100 Eugene Brooks Ave., Raleigh, NC 27695 USA
| | - Scott H McArt
- Department of Entomology, Cornell University, 4132 Comstock Hall, 129 Garden Ave., Ithaca, NY 14853 USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California, 43 Briggs Hall, Davis CA 95616 USA
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6
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Evolutionary and Ecological Considerations on Nectar-Mediated Tripartite Interactions in Angiosperms and Their Relevance in the Mediterranean Basin. PLANTS 2021; 10:plants10030507. [PMID: 33803275 PMCID: PMC7999006 DOI: 10.3390/plants10030507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 11/16/2022]
Abstract
The Mediterranean basin hosts a high diversity of plants and bees, and it is considered one of the world's biodiversity hotspots. Insect pollination, i.e., pollen transfer from male reproductive structures to conspecific female ones, was classically thought to be a mutualistic relationship that links these two groups of organisms, giving rise to an admirable and complex network of interactions. Although nectar is often involved in mediating these interactions, relatively little is known about modifications in its chemical traits during the evolution of plants. Here, we examine how the current sucrose-dominated floral nectar of most Mediterranean plants could have arisen in the course of evolution of angiosperms. The transition from hexose-rich to sucrose-rich nectar secretion was probably triggered by increasing temperature and aridity during the Cretaceous period, when most angiosperms were radiating. This transition may have opened new ecological niches for new groups of insects that were co-diversifying with angiosperms and for specific nectar-dwelling yeasts that originated later (i.e., Metschnikowiaceae). Our hypothesis embeds recent discoveries in nectar biology, such as the involvement of nectar microbiota and nectar secondary metabolites in shaping interactions with pollinators, and it suggests a complex, multifaceted ecological and evolutionary scenario that we are just beginning to discover.
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7
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Vannette RL. The Floral Microbiome: Plant, Pollinator, and Microbial Perspectives. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-013401] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Flowers at times host abundant and specialized communities of bacteria and fungi that influence floral phenotypes and interactions with pollinators. Ecological processes drive variation in microbial abundance and composition at multiple scales, including among plant species, among flower tissues, and among flowers on the same plant. Variation in microbial effects on floral phenotype suggests that microbial metabolites could cue the presence or quality of rewards for pollinators, but most plants are unlikely to rely on microbes for pollinator attraction or reproduction. From a microbial perspective, flowers offer opportunities to disperse between habitats, but microbial species differ in requirements for and benefits received from such dispersal. The extent to which floral microbes shape the evolution of floral traits, influence fitness of floral visitors, and respond to anthropogenic change is unclear. A deeper understanding of these phenomena could illuminate the ecological and evolutionary importance of floral microbiomes and their role in the conservation of plant–pollinator interactions.
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Affiliation(s)
- Rachel L. Vannette
- Department of Entomology and Nematology, University of California, Davis, California 95616, USA
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8
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Microbial Co-Occurrence in Floral Nectar Affects Metabolites and Attractiveness to a Generalist Pollinator. J Chem Ecol 2020; 46:659-667. [PMID: 32246258 DOI: 10.1007/s10886-020-01169-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/27/2020] [Accepted: 03/06/2020] [Indexed: 12/25/2022]
Abstract
Microbial metabolism can shape cues important for animal attraction in service-resource mutualisms. Resources are frequently colonized by microbial communities, but experimental assessment of animal-microbial interactions often focus on microbial monocultures. Such an approach likely fails to predict effects of microbial assemblages, as microbe-microbe interactions may affect in a non-additive manner microbial metabolism and resulting chemosensory cues. Here, we compared effects of microbial mono- and cocultures on growth of constituent microbes, volatile metabolite production, sugar catabolism, and effects on pollinator foraging across two nectar environments that differed in sugar concentration. Growth in co-culture decreased the abundance of the yeast Metschnikowia reukaufii, but not the bacterium Asaia astilbes. Volatile emissions differed significantly between microbial treatments and with nectar concentration, while sugar concentration was relatively similar among mono- and cocultures. Coculture volatile emission closely resembled an additive combination of monoculture volatiles. Despite differences in microbial growth and chemosensory cues, honey bee feeding did not differ between microbial monocultures and assemblages. Taken together, our results suggest that in some cases, chemical and ecological effects of microbial assemblages are largely predictable from those of component species, but caution that more work is necessary to predict under what circumstances non-additive effects are important.
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9
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Morris MM, Frixione NJ, Burkert AC, Dinsdale EA, Vannette RL. Microbial abundance, composition, and function in nectar are shaped by flower visitor identity. FEMS Microbiol Ecol 2020; 96:5700281. [DOI: 10.1093/femsec/fiaa003] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 01/08/2020] [Indexed: 11/12/2022] Open
Abstract
ABSTRACT
Microbial dispersal is essential for establishment in new habitats, but the role of vector identity is poorly understood in community assembly and function. Here, 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.
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Affiliation(s)
- Megan M Morris
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Natalie J Frixione
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Alexander C Burkert
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
| | | | - Rachel L Vannette
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
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10
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Schaeffer RN, Rering CC, Maalouf I, Beck JJ, Vannette RL. Microbial metabolites elicit distinct olfactory and gustatory preferences in bumblebees. Biol Lett 2019; 15:20190132. [PMID: 31311487 DOI: 10.1098/rsbl.2019.0132] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Animals such as bumblebees use chemosensory cues to both locate and evaluate essential resources. Increasingly, it is recognized that microbes can alter the quality of foraged resources and produce metabolites that may act as foraging cues. The distinct nature of these chemosensory cues however and their use in animal foraging remain poorly understood. Here, we test the hypothesis that species of nectar-inhabiting microbes differentially influence pollinator attraction and feeding via microbial metabolites produced in nectar. We first examined the electrophysiological potential for bumblebee (Bombus impatiens) antennal olfactory neurons to respond to microbial volatile organic compounds (mVOCs), followed by an olfactory preference test. We also assessed gustatory preferences for microbial-altered nectar through both no-choice and choice feeding assays. Antennal olfactory neurons responded to some mVOCs, and bees preferred nectar solutions inoculated with the bacterium Asaia astilbes over the yeast Metschnikowia reukaufii based on volatiles alone. However, B. impatiens foragers consumed significantly more Metschnikowia-inoculated nectar, suggesting distinct roles for mVOCs and non-volatile metabolites in mediating both attraction and feeding decisions. Collectively, our results suggest that microbial metabolites have significant potential to shape interspecific, plant-pollinator signalling, with consequences for forager learning, economics and floral host reproduction.
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Affiliation(s)
- Robert N Schaeffer
- Department of Entomology, Washington State University, Pullman, WA 99164, USA.,Department of Entomology and Nematology, University of California Davis, Davis, CA 95616, USA
| | - Caitlin C Rering
- Chemistry Research Unit, Center for Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL 32608, USA
| | - Isabelle Maalouf
- Department of Entomology and Nematology, University of California Davis, Davis, CA 95616, USA
| | - John J Beck
- Chemistry Research Unit, Center for Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL 32608, USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California Davis, Davis, CA 95616, USA
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11
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Madden AA, Epps MJ, Fukami T, Irwin RE, Sheppard J, Sorger DM, Dunn RR. The ecology of insect-yeast relationships and its relevance to human industry. Proc Biol Sci 2019; 285:rspb.2017.2733. [PMID: 29563264 DOI: 10.1098/rspb.2017.2733] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 02/28/2018] [Indexed: 01/03/2023] Open
Abstract
Many species of yeast are integral to human society. They produce many of our foods, beverages and industrial chemicals, challenge us as pathogens, and provide models for the study of our own biology. However, few species are regularly studied and much of their ecology remains unclear, hindering the development of knowledge that is needed to improve the relationships between humans and yeasts. There is increasing evidence that insects are an essential component of ascomycetous yeast ecology. We propose a 'dispersal-encounter hypothesis' whereby yeasts are dispersed by insects between ephemeral, spatially disparate sugar resources, and insects, in turn, obtain the benefits of an honest signal from yeasts for the sugar resources. We review the relationship between yeasts and insects through three main examples: social wasps, social bees and beetles, with some additional examples from fruit flies. Ultimately, we suggest that over the next decades, consideration of these ecological and evolutionary relationships between insects and yeasts will allow prediction of where new yeast diversity is most likely to be discovered, particularly yeasts with traits of interest to human industry.
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Affiliation(s)
- Anne A Madden
- Department of Applied Ecology, North Carolina State University, David Clark Labs, 100 Brooks Avenue, Raleigh, NC 27607, USA
| | - Mary Jane Epps
- Department of Biology, Mary Baldwin University, 101 East Frederick Street, Staunton, VA 24401, USA
| | - Tadashi Fukami
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, David Clark Labs, 100 Brooks Avenue, Raleigh, NC 27607, USA
| | - John Sheppard
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 400 Dan Allen Drive, Raleigh, NC 27606, USA
| | - D Magdalena Sorger
- Department of Applied Ecology, North Carolina State University, David Clark Labs, 100 Brooks Avenue, Raleigh, NC 27607, USA.,Research & Collections, North Carolina Museum of Natural Sciences, 11 West Jones Street, Raleigh, NC 27601, USA
| | - Robert R Dunn
- Department of Applied Ecology, North Carolina State University, David Clark Labs, 100 Brooks Avenue, Raleigh, NC 27607, USA.,Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, 2100 Copenhagen Ø, Denmark.,German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany
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12
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Russell AL, Ashman TL. Associative learning of flowers by generalist bumble bees can be mediated by microbes on the petals. Behav Ecol 2019. [DOI: 10.1093/beheco/arz011] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Abstract
Communication is often vital to the maintenance of mutualisms. In plant-pollinator mutualisms, plants signal pollinators via floral displays, composed of olfactory, visual, and other plant-derived cues. While plants are understood to be associated with microbes, only recently has the role of microbial (yeast and bacteria) inhabitants of flowers as intermediaries of plant-pollinator communication been recognized. Animals frequently use microbial cues to find resources, yet no study has examined whether microbes directly mediate learned and innate pollinator responses. Here, we asked whether microbes on the flower surface, independent of their modification of floral rewards, can mediate these key components of pollinator preference. In the field, we characterized flower and bumble bee microbial abundance, and in laboratory assays we tested whether bumble bees (Bombus impatiens) discriminated flowers on the basis of an experimental floral microbial community on the petals and whether microbe-derived chemicals were effective cues. Learning of microbial community cues was associative and reward context-dependent and mediated by microbial chemicals. Deconstructing the experimental microbial community showed bees innately avoided flowers with bacteria, but were undeterred by yeast. Microbial cues thus potentially facilitate dynamic communication between plants and pollinators such as bumble bees, especially as pollinator visitation can change flower microbiota. We suggest that the study of communication in mutualism generally would benefit by considering not only the multicellular eukaryote partners, but their microbial associates.
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Affiliation(s)
- Avery L Russell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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13
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Rering CC, Beck JJ, Hall GW, McCartney MM, Vannette RL. Nectar-inhabiting microorganisms influence nectar volatile composition and attractiveness to a generalist pollinator. THE NEW PHYTOLOGIST 2018; 220:750-759. [PMID: 28960308 DOI: 10.1111/nph.14809] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 08/21/2017] [Indexed: 05/18/2023]
Abstract
The plant microbiome can influence plant phenotype in diverse ways, yet microbial contribution to plant volatile phenotype remains poorly understood. We examine the presence of fungi and bacteria in the nectar of a coflowering plant community, characterize the volatiles produced by common nectar microbes and examine their influence on pollinator preference. Nectar was sampled for the presence of nectar-inhabiting microbes. We characterized the headspace of four common fungi and bacteria in a nectar analog. We examined electrophysiological and behavioral responses of honey bees to microbial volatiles. Floral headspace samples collected in the field were surveyed for the presence of microbial volatiles. Microbes commonly inhabit floral nectar and the common species differ in volatile profiles. Honey bees detected most microbial volatiles tested and distinguished among solutions based on volatiles only. Floral headspace samples contained microbial-associated volatiles, with 2-ethyl-1-hexanol and 2-nonanone - both detected by bees - more often detected when fungi were abundant. Nectar-inhabiting microorganisms produce volatile compounds, which can differentially affect honey bee preference. The yeast Metschnikowia reukaufii produced distinctive compounds and was the most attractive of all microbes compared. The variable presence of microbes may provide volatile cues that influence plant-pollinator interactions.
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Affiliation(s)
- Caitlin C Rering
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr., Gainesville, FL, 32608, USA
| | - John J Beck
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, 1700 SW 23rd Dr., Gainesville, FL, 32608, USA
| | - Griffin W Hall
- Department of Entomology and Nematology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | - Mitchell M McCartney
- Mechanical and Aerospace Engineering, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
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14
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Chappell CR, Fukami T. Nectar yeasts: a natural microcosm for ecology. Yeast 2018; 35:417-423. [PMID: 29476620 DOI: 10.1002/yea.3311] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/09/2018] [Accepted: 02/09/2018] [Indexed: 11/10/2022] Open
Abstract
The species of yeasts that colonize floral nectar can modify the mutualistic relationships between plants and pollinators by changing the chemical properties of nectar. Recent evidence supporting this possibility has led to increased interest among ecologists in studying these fungi as well as the bacteria that interact with them in nectar. Although not fully explored, nectar yeasts also constitute a promising natural microcosm that can be used to facilitate development of general ecological theory. We discuss the methodological and conceptual advantages of using nectar yeasts from this perspective, including simplicity of communities, tractability of dispersal, replicability of community assembly, and the ease with which the mechanisms of species interactions can be studied in complementary experiments conducted in the field and the laboratory. To illustrate the power of nectar yeasts as a study system, we discuss several topics in community ecology, including environmental filtering, priority effects, and metacommunity dynamics. An exciting new direction is to integrate metagenomics and comparative genomics into nectar yeast research to address these fundamental ecological topics.
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Affiliation(s)
- Callie R Chappell
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tadashi Fukami
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
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15
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Fungal Honeydew Elements as Potential Indicators of the Botanical and Geographical Origin of Honeys. FOOD ANAL METHOD 2017. [DOI: 10.1007/s12161-017-0862-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Schaeffer RN, Mei YZ, Andicoechea J, Manson JS, Irwin RE. Consequences of a nectar yeast for pollinator preference and performance. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12762] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Robert N. Schaeffer
- Department of Biological Sciences Dartmouth College Hanover New Hampshire03755 USA
| | - Yu Zhu Mei
- Department of Biological Sciences Dartmouth College Hanover New Hampshire03755 USA
| | - Jonathan Andicoechea
- Department of Biological Sciences Dartmouth College Hanover New Hampshire03755 USA
| | - Jessamyn S. Manson
- Department of Biology University of Virginia Charlottesville Virginia22904 USA
| | - Rebecca E. Irwin
- Department of Biological Sciences Dartmouth College Hanover New Hampshire03755 USA
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