Carnivorous Pitcher Plants Support Their Microbiome with Nectar: Tracing Host Nectar Carbon and Nitrogen Microbial Incorporation Using Stable Isotope Labeling

Biological Sciences, College of Letters & Science, Holzer, Amanda, Mentor, Poster Presentation, School and College, Student, Young, Erica

Amanda Holzer, “Carnivorous Pitcher Plants Support Their Microbiome with Nectar: Tracing Host Nectar Carbon and Nitrogen Microbial Incorporation Using Stable Isotope Labeling”
Mentor: Erica Young, Biological Sciences
Poster #101

The carnivorous pitcher plant, Sarracenia purpurea, hosts a microbial community which works in a mutualistic relationship within host pitchers. The traps of S. purpurea captures insect prey which are broken down by the microbial community to provide nutrients for the host plant. To attract insects, S. purpurea secretes nectar along the nectar roll at the top edge of the pitcher, which encourages insects to sample the nectar where they may fall into the trap. This research aimed to test the hypothesis that nectar washed into pitchers by rainfall can also contribute carbon and nitrogen resources to support microbial communities inside pitchers. During summer 2023, nectar was collected from >25 pitchers from S. purpurea plants in a population at the Cedarburg Bog and measured total carbohydrate and amino acid content to identify the sugar:amino acid ratio in natural nectar. An artificial nectar containing isotopically enriched sugar and amino acids with 15N- and 13C-labelled methionine, valine, and glucose. In a greenhouse experiment, this labelled nectar was painted onto the nectar roll, dried overnight and then sprayed with sterile water to simulate rain, 3 times weekly for 4 weeks. Pitcher water was sampled and analyzed in a mass spectrometer for nectar 15N and 13C incorporation into the microbial community. DNA sequencing will be used to determine bacterial community composition and compared with communities not receiving artificial nectar treatments. Mass spectrometry results revealed an increase in 15N and 13C in the pitcher microbial community over time when provided with isotopically enriched nectar showing incorporation of the nectar C and N. These experiments show that when nectar from the host plant is washed into the pitcher, it may provide carbon and nitrogen to support microbiome growth.