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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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Genomic and transcriptomic resources for candidate gene discovery in the Ranunculids
PremiseMultiple transitions from insect to wind pollination are associated with polyploidy and unisexual flowers inThalictrum(Ranunculaceae), yet the underlying genetics remains unknown. We generated a draft genome ofThalictrum thalictroides, a representative of a clade with ancestral floral traits (diploid, hermaphrodite, and insect pollinated) and a model for functional studies. Floral transcriptomes ofT. thalictroidesand of wind‐pollinated, andromonoeciousT. hernandeziiare presented as a resource to facilitate candidate gene discovery in flowers with different sexual and pollination systems. MethodsA draft genome ofT. thalictroidesand two floral transcriptomes ofT. thalictroidesandT. hernandeziiwere obtained from HiSeq 2000 Illumina sequencing and de novo assembly. ResultsTheT. thalictroidesde novo draft genome assembly consisted of 44,860 contigs (N50 = 12,761 bp, 243 Mbp total length) and contained 84.5% conserved embryophyte single‐copy genes. Floral transcriptomes contained representatives of most eukaryotic core genes, and most of their genes formed orthogroups. DiscussionTo validate the utility of these resources, potential candidate genes were identified for the different floral morphologies using stepwise data set comparisons. Single‐copy gene analysis and simple sequence repeat markers were also generated as a resource for population‐level and phylogenetic studies.
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- Award ID(s):
- 1911539
- PAR ID:
- 10453684
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Applications in Plant Sciences
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2168-0450
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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