Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Francis, Jacob [1], Mueller, Tobias G [1], Vannette, Rachel L [1].

Intraspecific variation in nectar microbiome among co-occurring cultivars of Epilobium canum.

Flowers host communities of bacteria and fungi that can affect plant reproduction directly and influence pollinator behavior, including pollen transfer. While intraspecific variation in floral traits such as structure, color, and pollinator reward have well documented effects on plants' interactions with macroorganisms, much less is known about how individual and population level variation in floral traits impacts interactions with microbes. Here we used a combination of surveys and controlled microbial manipulations of the nectar of  Epilobium canum  (Greene, Onagraceae) to investigate sub-species level variation in nectar microbiome abundance and structure. We constructed a common garden of four distinct cultivars of  E. canum. Using a culture based approach, we characterized nectar microbe communities of 320 open-visited flowers across 8 plants (10 flowers per plant) of each cultivar. We found significant intraspecific variation in standing nectar microbe densities. Within a cultivar, individual plants differed in the density (colony forming units per  mL of nectar) of nectar dwelling bacteria (log-LME, LRT,  Î§²=56.01, p=0.001) and fungi (log-LME, LRT,  Î§²=39.30, p =0.046). Despite variation among plants within a cultivar, cultivars also differed significantly in bacterial densities (log-LME, LRT,  Î§²=16.35, p=0.0009)    and fungal densities (log-LME, LRT,  Î§²=10.81, p = 0.013). To investigate whether these differences were driven by animal-mediated dispersal limitation or differences in plant traits, we limited animal access to 172 flowers across 6-7 individual plants per cultivar. We inoculated these flowers with ten thousand cells each of the nectar yeast  Metschnikowia koreensis  and nectar bacteria  Acinetobacter pollinisisolated from flowers at the site, then harvested flowers after two days. After inoculation, there was no difference in  A. pollinis  growth among plants (log-LME, LRT, Χ²=34.47, p=0.15) or cultivars (log-LME, LRT,  Î§²=5.91, p=0.12). Alternatively, there were strong significant differences in  M. koreensis  densities among plants  (log-LME, LRT,  Î§²=123.41, p<0.0001), but not cultivars (log-LME, LRT,  Î§²=1.44, p=0.69). Together, the common garden based nectar-microbe survey and experimental inoculations demonstrate significant individual and cultivar level variation nectar microbiome. Ongoing work will examine floral and nectar traits that may be associated with variation in microbial growth. However, when comparing between the survey and experiment, microbial densities were not correlated among plant individuals or cultivars. In other words, plants that hosted high microbial growth when open to visitation were not necessarily those that hosted the highest microbial growth in inoculation experiments. This suggests that both floral traits and microbe dispersal limitation might play a role in shaping a plants' nectar microbiome.

1 - University Of California Davis, Entomology and Nematology, 1 Shields Ave., Davis , CA, 95616, USA

Keywords:
nectar
Microbiome
Metschnikowiaceae
Onagraceae
Acinetobacter
natural variation
common garden.

Presentation Type: Oral Paper
Session: SYMB2, Symbioses: Plant, Animal and Microbe Interactions 2
Location: /
Date: Tuesday, July 20th, 2021
Time: 1:30 PM(EDT)
Number: SYMB2005
Abstract ID:946
Candidate for Awards:None