DNA Metabarcoding of Pollen

DNA metabarcoding” is the use of genetic markers to taxonomically identify mixed-species samples, using high-throughput DNA sequencing. We got interested in developing methods for DNA metabarcoding of pollen in order to build highly-resolved pollination networks via molecular identification of pollen carried by pollinators, but it also has a range of other interesting and important applications from forensics to provenance identification to paleontology. Our past methods development work on this topic, and our current work on quantitation, have been supported by the Army Research Office.  Karen Bell, a former post-doc in our lab and currently a faculty member at the University of Western Australia and CSIRO, is a key collaborator in this work.

Key Publications

Bell KL, Burgess KS, Dobbs EK, Botsch JC, Read TD, Brosi BJ. 2019. Quantitative and qualitative and assessment of pollen DNA metabarcoding using constructed species mixtures. Molecular Ecology, 28:431–455
Lucas A, Bodger O, Brosi BJ, Ford C, Forman D, Greig C, Hegarty M, Neyland P, de Vere N. 2018. Generalisation and specialisation in hoverfly (Syrphidae) grassland pollen transport networks revealed by DNA metabarcoding. Journal of Animal Ecology, 87:1008–1021
Lucas A, Bodger O, Brosi BJ, Ford C, Forman D, Greig C, Hegarty M, Neyland P, de Vere N. 2018. Floral resource partitioning by individuals within generalised hoverfly pollination networks revealed by DNA metabarcoding. Scientific Reports, 8: 5133
Bell KL, Fowler J, Burgess KS, Dobbs EK, Gruenewald D, Lawley B, Morozumi C, Brosi BJ. Applying pollen DNA metabarcoding to the study of plant-pollinator interactions. Applications in Plant Sciences, 2017. 5(6): 1600124

This work shows the integration between our DNA metabarcoding work and our network studies—demonstrating for the first time that highly-resolved pollination networks can be constructed by metabarcoding pollen carried by flower visitors. We highlight a number of suggestions for using this technique for network studies.

Bell KL, Loeffler VM, Brosi BJ. 2017. An rbcL reference library to aid in the identification of plant species mixtures by DNA metabarcoding. Applications in Plant Sciences, 5(3): 1600110
Bell K.L., N. De Vere, A. Keller, R. Richardson, A. Gous, , K.S. Burgess, B.J. Brosi. Pollen DNA barcoding: current applications and future prospects. Genome, 2016. 59(9): 629-640

This review lays out the current status of pollen metabarcoding, including its promise as a technique, its limitations, and key areas for future research.

Bell, K.L., K.S. Burgess, K.C. Okamoto, R. Aranda, B.J. Brosi. 2016. Review and future prospects of DNA barcoding methods in forensic palynology. Forensic Science International: Genetics, 21: 110-116
Bee and wildflower


While metabarcoding works well for establishing the presence of particular species, it performs poorly in establishing relative proportions of species in a sample. With funding from the Army Research Office (2017-2020) and in collaboration with Karen Bell (UWA) and Tim Read (Emory), we have just begun a project to develop methods for quantitative pollen metabarcoding, by correcting for isolation, copy number, and amplification biases using both new laboratory assays (with samples designed in a phylogenetic context) and with informatics approaches. We are currently recruiting a post-doc with experience in bioinformatics and statistics to work on this project. In exploring topics like organellar copy number in a phylogenetic context, this work also has interesting potential implications for the evolution of organellar genomes in a phylogenetic context and for transgene containment.

In work driven by Natasha De Vere (National Botanical Garden of Wales) and her doctoral student Andrew Lucas, we are collaborating on studies focused on understanding the structure and dynamics of syrphid fly pollen transport networks. This work is taking place in Wales, whose entire flora is included in DNA barcode libraries, making it an ideal test case for integrating metabarcoding into ecological studies.