Our team

Broadly, I am interested in how microbial communities assemble in seeds and persist throughout seed development. I am also interested in monitoring the biodiversity of microbial communities in seeds, and using seed microbiota for sustainable agriculture and plant conservation.

Education

2020-2025: University of California, Davis

Doctor of Philosophy (Ph.D.) in Ecology, Emphasis in Landscape and Ecosystem Ecology, GPA: 3.84

2015-2019: Oregon State University Honors College

Bachelor of Science (Honors) in BioResource Research (Magna Cum Laude), Minor in Soil Science, GPA: 3.83

Professional/Research Experience

2025-present: Postdoctoral Researcher in Seed Microbiomes and Bioinformatics with Dr. Ahmed Abdelfattah, Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB Potsdam), Potsdam, Germany.

2024: Visiting Graduate Researcher with Dr. Matthieu Barret and Dr. Marie Simonin, INRAE Institute for Research on Horticulture and Seeds (IRHS), Angers, France (8 months).

2020-2025: NSF/UC Davis Dean’s Distinguished Graduate Research Fellow with Dr. Johan Leveau and Dr. Rachel Vannette, Plant Pathology/Entomology and Nematology, UC Davis. Dissertation title: Contributions of floral transmission to bacterial community assembly in developing seeds of watermelon (Citrullus lanatus).

2019-2020: Faculty Research Assistant with Dr. Posy Busby and Dr. Jared LeBoldus, Botany and Plant Pathology, Oregon State University.

2017-2019: Honors Undergraduate Research Intern with Dr. Posy Busby, Botany and Plant Pathology, Oregon State University. Honors thesis title: Geographic variation in the seed mycobiome of Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii).

2018: Visiting Undergraduate Intern with Dr. Helen Whelan, Dr. John Hampton and Dr. Travis Glare, Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand. (4 months)

2017: NSF-REU Undergraduate Intern with Dr. Posy Busby, Botany and Plant Pathology, Oregon State University, Corvallis, OR.

2016-2017: Student Archivist with Oregon Hops and Brewing Archives, Special Collections and Archives Research Center, Oregon State University, Corvallis, OR.

2016: Undergraduate Research Intern with Dr. Steve Strauss, Forest Ecosystems and Society, Oregon State University, Corvallis, OR.

Teaching and Mentoring

2024: Guest lecturer for UE4 (Biology and Biotechnology of Seeds and Plant Propagation) at the Institut Agro Rennes-Angers, Angers, France.

2024: Guest lecturer for UE6 (Ecology of Microbial Communities Associated with Plants) at the University of Angers, Angers, France.

2024: Guest lecturer for BIO294B (Seminar in Ecology, Evolution and Conservation) at California State University-Sacramento (CSUS).

2024-2025: Mentor for an honors undergraduate student on her year-three independent project and year-four thesis. Thesis title: Variation in biocontrol effects of stigma- and seed-borne Bacillus against Fusarium wilt in watermelon (Citrullus lanatus).

2024: Mentor to two PhD students on preparations for their qualifying exams as part of the UC Davis QE Support Group. Provided insight on my experience preparing for the qualifying exam, as well as feedback on student drafts of their written proposals and proposal presentations. Also participated in weekly meetings of the support group.

2023: Mentor to two community college students on projects characterizing ecological functions of seed- and stigma-associated microbes of watermelon. Students joined the lab through the Woodland Community College-MESA Summer Undergraduate Research Program.

2022-2023: Mentor to two undergraduate students on a culture-based survey of seed- and stigma-associated microbes of watermelon. Taught students sterile technique, culturing methods for bacteria and fungi, preparing said microbes for long-term storage, DNA extraction, PCR, gel electrophoresis, processing Sanger sequence data for identification with NCBI Genbank, and data visualization and analysis.

2022: Student organizer for Ecology (ECL) 290 course: Biology and Ecology of Plant Reproduction, sponsored by Dr. Susan Harrison, Dr. Rachel Vannette and Dr. Neal Williams.

2022: Mentor to a high school student on a culture-based survey of seed- and stigma-associated microbes of watermelon. Taught the student sterile technique, culturing of plant tissues for microbial emergence and isolating microbes into pure culture.

2021: Student organizer for Ecology (ECL) 290 course: Theoretical Models in Metacommunity Ecology, sponsored by Dr. Alan Hastings and Dr. Marcel Holyoak.

2021: Mentor for a rotating microbiology Ph.D. student on longitudinal profiling of the Citrus leaf microbiota. Taught the student bioinformatic processing of metabarcoding data and data visualization in R.

2020: Mentor for an honors undergraduate student characterizing culturable fungal wood endophytes of Populus trichocarpa. Taught the student field sampling methods, sterile technique, culturing plant tissue for fungal isolation, and isolating fungi into pure culture.

Scientific publications

*= undergraduate/community college mentee

Nelson RA, GE Bergmann, E Jochim and FS Valdovinos. In prep. The spillover of floral fungi across ecological boundaries. (co-first author)

Miller MGA, GE Bergmann, RI Alcalá Briseño, Y Lan, KL Søndreli, PE Busby and JM LeBoldus. In prep. The interaction between Septoria stem canker and the mycobiome of Populus trichocarpa stems.

Bergmann GE, Lui K*, Lopez C*, Velasco A*, Marais C, Barret M, Simonin M, Vannette RL, and JHJ Leveau. 2025. Contribution of floral transmission to the assembly and health impact of bacterial communities in watermelon seeds. bioRxiv. https://doi.org/10.1101/2025.02.12.637993

Bergmann GE, Heitmann, SJ, Busby, PE and JHJ Leveau. 2023. Characterization of Seed Mycobiota Using Culture-Dependent and Culture-Independent Approaches. In Microbial Environmental Genomics (MEG) (pp. 65-78). New York, NY: Springer US.

Bergmann GE and JHJ Leveau. 2022. A metacommunity ecology approach to understanding microbial community assembly in developing plant seeds. Frontiers in Microbiology 13. DOI: https://doi.org/10.3389/fmicb.2022.877519

Bergmann GE and PE Busby. 2021. The core seed mycobiome of Pseudotsuga menziesii var. menziesii across provenances of the Pacific Northwest, USA. Mycologia 113(6): 1169-1180. DOI: 10.1080/00275514.2021.1952830.

Heitmann S, GE Bergmann, E Barge, M Ridout, G Newcombe and PE Busby. 2021. Culturable seed microbiota of Populus trichocarpa. Pathogens 10(6): 653. https://doi.org/10.3390/pathogens10060653

Bergmann GE. 2019. Impacts of pesticide pollution on soil microbial communities, ecosystem function and human health. Reference Module in Earth Systems and Environmental Sciences. https://doi.org/10.1016/B978-0-12-409548-9.11269-2.

Other publications and media

Candeias M. 2025. Exploring the Seed Microbiome. In Defense of Plants (podcast interview). https://www.indefenseofplants.com/podcast/2025/8/12/ep-539-exploring-the-seed-microbiome

Goss B and GE Bergmann. 2024. Is it just science? Aggie Brickyard Volume XIV ‘Mosaics,’ UC Davis Graduate Group in Ecology, pages 10-11. https://aggiebrickyard.github.io/posts/FallVol/

Bergmann GE. 2024. The ephemeral landscape of the floral stigma. UC Davis Ecology Graduate Symposium, Davis, CA. (Photograph exhibition)

Bergmann GE. 2023. "Creature Feature: Douglas Squirrel." The Ethogram, UC Davis Graduate Group in Animal Behavior. https://theethogram.com/2023/10/03/creature-feature-douglas-squirrel/

Bergmann GE. 2021. “Daybreak.” Aggie Brickyard Volume XI ‘Mileposts,’ UC Davis Graduate Group in Ecology, page 22. https://aggiebrickyard.github.io/posts/WinterVolume-XI/

“Student Spotlight January 2020.” 2020. Mycological Society of America Student-Postdoc Section. https://msastudents.org/student-spotlights/current-student-spotlight/

“A Fungus Among Us.” 2018. Faces of Ag Sci, Oregon State University. https://agsci.oregonstate.edu/feature/fungus-among-us

Invited Oral Presentations

Bergmann GE. 2024. Assessing the role of floral transmission to seed bacterial community assembly in watermelon (Citrullus lanatus). Graduate Student Research group on Plant Microbiomes, Wageningen University and Research, Wageningen, The Netherlands, September 16.

Bergmann GE and PE Busby. 2022. The core seed mycobiome of Pseudotsuga menziesii var. menziesii across provenances of the Pacific Northwest, USA. American Phytopathological Society webinar: The Role of the Microbiome in Forest Disease, Regeneration, and Biodiversity, October 12 (virtual).

Bergmann GE. 2021. The mysteries of seed microbes. Deschutes Public Library Webinar Series, October 19, Davis, CA (virtual). https://www.deschuteslibrary.org/calendar/event/62584.

Bergmann GE. 2020. From seed to stem (and back again): my journey in plant microbiome research. Meristems speaker series, Oregon State University Botany and Plant Pathology Club, February 26, Corvallis, OR.

Submitted Oral Presentations

*= undergraduate/community college mentee

Bergmann GE, L Colaert-Sentenac, A Darrasse, M Brunel, L Suteau, C Marais, M Briand, M Simonin, M Barret & JHJ Leveau. 2025. Bacterial arrival order during floral transmission affects pathogen infection of seeds, and microbiota assembly in seedlings. Seed Microbiome Working Group Quarterly Meeting (virtual).

Bergmann GE. 2025. Stigma bacterial communities impact fruit development and pathogen transmission to seeds. UC Davis Ecology Graduate Symposium, Davis, CA.

Bergmann GE. 2024. Floral stigmas and developing seeds share functionally diverse bacterial communities in commercial watermelon (Citrullus lanatus). UC Davis Ecology Graduate Symposium, Davis, CA.

Bergmann GE, CM Lopez*, K Lui*, A Velasco*, RL Vannette, and JHJ Leveau. 2023. Overlap between stigma and seed bacterial communities of watermelon (Citrullus lanatus) and their effects on seedling vigor. 2nd Young AMICI Symposium, virtual. Bergmann GE. 2022. Testing the transmission of microbes from flowers to seeds. UC Davis Ecology Graduate Group Recruitment Symposium, February 4, Davis CA (virtual).

Bergmann GE. 2019. Identity and drought tolerance effects of fungal seed endophytes in Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii). Oregon State University Honors College thesis seminar, May 24, Corvallis, OR.

Bergmann GE, S Hatwal, E Barge, K Gervers, H Whelan and PE Busby. 2019. Fungi in Douglas-fir seeds: Who are they, and what are they doing? Cascade Mycological Society general meeting, April 17, Eugene, OR.

Bergmann GE. 2018. Provenance-based characterization of Pseudotsuga menziesii fungal seed endophytes and their involvement in seedling drought tolerance. OSU Mycology Club meeting, May 29, Corvallis, OR.

Poster Presentations

*= undergraduate/community college mentee, +=high school mentee

K Lui*, GE Bergmann and JHJ Leveau. 2025. Impact of Bacillus strains on Watermelon seed germination under Fusarium infection. UC Davis Undergraduate Research and Creative Activities Conference (URSCA), Davis, CA.

GE Bergmann, C Marais, M Simonin, M Barret, RL Vannette and JHJ Leveau. 2024. Contribution of floral transmission to seed microbiota assembly in watermelon. 5th Plant Microbiome Symposium, Amsterdam, The Netherlands.

MGA Miller, GE Bergmann, RI Alcalá Briseño, Y Lan, KL Søndreli, PE Busby and JM LeBoldus. 2024. The interaction between Septoria stem canker and the mycobiome of Populus trichocarpa stems. Joint Meeting of the APS Pacific Division and Conference on Soilborne Plant Pathogens, Corvallis, Oregon, USA.

GE Bergmann, RL Vannette and JHJ Leveau. 2024. Overlap between stigma and seed bacterial communities of watermelon (Citrullus lanatus). 63rd Annual ASTA Flower and Vegetable Seed Conference, Monterey, CA. GE

Bergmann, RL Vannette and JHJ Leveau. 2023. Overlap between stigma and seed bacterial communities of watermelon (Citrullus lanatus). UC Davis Research Retreat on Host-Microbe Interactions, Tahoe City, CA.

Barragan K*, GE Bergmann, RL Vannette and JHJ Leveau. 2023. Diverse pairwise interactions between flower- and seed-borne microbes of watermelon (Citrullus lanatus). WCC-MURSP poster symposium, Davis, CA.

Lopez CM*, GE Bergmann, RL Vannette and JHJ Leveau. 2023. Stigma- and seed-sourced microbes of watermelon (Citrullus lanatus) influence seedling health. WCC-MURSP poster symposium, Davis, CA. (POSTER)

Lui K*, AM Velasco*, GE Bergmann, R Mahajan+, RL Vannette and JHJ Leveau. 2023. What microbes are found in watermelon (Citrullus lanatus) flowers and seeds? UC Davis Undergraduate Research and Creative Activities Conference (URSCA), Davis, CA.

Bergmann GE, E Barge, H Whelan and PE Busby. 2019. Exploring the identity and function of fungal seed endophytes of Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii). Mycological Society of America meeting, August 12, Minneapolis, MN.

Bergmann GE, S Hatwal, E Barge, K Gervers, H Whelan and PE Busby. 2019. Exploring the identity and function of fungal seed endophytes in Douglas-fir (Pseudotsuga menziesii). OSU Undergraduate Showcase of Biological and Ecological Research, April 13, Corvallis, OR.

Bergmann GE, S Hatwal, E Barge, K Gervers, H Whelan and PE Busby. 2019. Exploring the identity and function of fungal seed endophytes in Douglas-fir (Pseudotsuga menziesii). OSU Microbiology Student Association Research Symposium, April 13, Corvallis, OR.

Bergmann GE, E Elorriaga, C Ma and SH Strauss. 2016. Gene editing in trees. OSU Celebrating Undergraduate Excellence Symposium. Corvallis, OR.

Grants, Scholarships, Awards and Honors

2024: Jastro & Shields Graduate Research Award, University of California-Davis ($2738)

2024: France-Berkeley Fund Grant, University of California ($12,000 – co-written with Dr. Johan Leveau and Dr. Matthieu Barret)

2024: Global Grad Grant- Research Track, University of California-Davis ($2000)

2023: Jastro & Shields Graduate Research Award, University of California-Davis ($3000)

2022: Jastro & Shields Graduate Research Award, University of California-Davis ($2363)

2020: Graduate Research Award, Sonoma County Mycological Association ($1000)

2020-2025: National Science Foundation (NSF) Graduate Research Fellow ($34,000 per year, three tenure years)

2020-2024: University of California-Davis Dean’s Distinguished Graduate Fellow ($28,000 per year, three tenure years)

2019: Best Undergraduate Poster Presentation Prize, Mycological Society of America ($100)

2019: Best Poster Presentation Prize, Oregon State University Undergraduate Showcase of Biological and Ecological Research ($50)

2019: Student Mentor Travel Award, Mycological Society of America ($750)

2018: Inductee, Gamma Sigma Delta Agriculture Honor Society

2018: Benjamin A. Gilman International Scholar ($4500)

2018: Honors College Experiential Scholarship, Oregon State University ($1000)

2018: Undergraduate Research Award, Mycological Society of America ($500)

2018: Freeman Rowe Educational Scholarship, Cascade Mycological Society ($1000)

2017: NSF Research Experience for Undergraduates (REU) in Microbial Ecology

2017: E.R. Jackman Friends and Alumni Scholarship ($2000)

2016: Inductee, National Society of Collegiate Scholars

2016: Waldo-Cummings Outstanding Student Award, Oregon State University

2016: Undergraduate Research, Scholarship and the Arts Award, Oregon State University ($1000)

2016: Honors College DeLoach Work Scholarship, Oregon State University ($1000)

2015-2019: Presidential Scholar, Oregon State University ($10,000 per year, four tenure years)

2015-2019: Honors Scholar, Oregon State University

Professional Service and Development

2025-present: Member of the Microbes and Social Equity Working Group

2025: Certificate in Peer Review from Nature Masterclasses

2024: Certificate in Global Leadership-Research Track from UC Davis Global Affairs

2024-present: Member of the American Phytopathological Society (APS)

2023-2024: Admissions Reviewer for the UC Davis Graduate Group in Ecology

2023-present: Peer Reviewer for Functional Ecology, BMC Plant Biology, Microbial Biotechnology, Tree Physiology, Environmental Microbiome, Phytobiomes Journal, BMC Microbiology, ISME J and FEMS Microbiology Ecology.

2022-2024: Speaker host for the UC Davis Ecology and Evolution Seminar Series

2022-present: Member of the Seed Microbiome Working Group

2022: Volunteer at the 11th International Symposium on Leaf Surface Microbiology (Phyllosphere 2022)

2021-2022: Mentee in the UC Davis First-Gen Grads Peer Mentoring Program

2020-2021: Communication Chair of the Mycological Society of America Student-Postdoc Section

2018-2021: Member of the Mycological Society of America

2017-2020: Member of the Cascade Mycological Society

2017: Certificate in “Introduction to R and RStudio” workshop from Oregon State University

Community Outreach

2025: Mentor with the UC Davis Transitioning from PUIs to Graduate School program

2023-2024: Mycoblitz planning committee member with the Redwood Forest Foundation Inc.

2023-2024: Mentor with the UC Davis Guardian Scholars Program

2022-2023: Science Communication Volunteer with Graduate Student & Post-Doctoral SACNAS Chapter @ UC Davis

2022-2024: Graduate Student Mentor with the UC Davis Ecology and Evolution Graduate School Preview Program

2019-2020: Staff Mentor with the Oregon State University Mycology Club

2019: CACP Conversants Volunteer with INTO OSU, Oregon State University

2018: Student Course Representative with the Lincoln University Student Association, Lincoln, New Zealand

2018: Tree Planting Volunteer with the Te Ara Kakariki Greenway Canterbury Trust, New Zealand

2016-2017: Challenge Day Group Leader with the OSU Science & Math Investigative Learning Experiences

2015-2019: Family Camp Counselor with Candlelighters for Children with Cancer

References

Ahmed Abdelfattah, Scientist and Team Leader

Microbiome Management Working Group

Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB Potsdam)

AAbdelfattah@atb-potsdam.de

Johan H.J. Leveau, Professor

Department of Plant Pathology, University of California-Davis

jleveau@ucdavis.edu

Rachel L. Vannette, Associate Professor and Vice Chair

Department of Entomology and Nematology, University of California-Davis

rlvannette@ucdavis.edu

Marcel Holyoak, Professor and Associate Dean

Department of Environmental Science and Policy, University of California-Davis

maholyoak@ucdavis.edu

Matthieu Barret, Scientist and Team Leader

Team on Emergence, systematics and ecology of plant pathogenic bacteria (EmerSys)

INRAE Institute for Research on Horticulture and Seeds (INRAE-IRHS)

matthieu.barret@inrae.fr

Marie Simonin, Scientist

Team on Emergence, systematics and ecology of plant pathogenic bacteria (EmerSys)

INRAE Institute for Research on Horticulture and Seeds (INRAE-IRHS)

marie.simonin@inrae.fr