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Smithsonian Botanical Symposium
The 2021 Smithsonian Botanical Symposium: Day 2
Plant Symbiosis: The Good, the Bad, and the Complicated

The Department of Botany and the United States Botanic Garden will hold the 2021 Smithsonian Botanical Symposium, “Plant symbiosis: the good, the bad, and the complicated,” virtually, on May 13th and 14th.

Plants, like all organisms, exist in collaboration and competition with other life forms. As primary producers, plants form the basis of most food webs. In many cases, they also depend on insects, vertebrate animals, bacteria, and/or fungi to survive and reproduce. Sometimes, these interactions are especially close and long lasting and such symbioses are among the most fascinating relationships in the natural world. The 18th Smithsonian Botanical Symposium will explore current research in the diversity of plant symbioses, examining the relationships plants have with insects, fungi, bacteria, and even other plants. Each day’s session will culminate with a virtual panel Q&A session. Speakers will include botanists, ecologists, microbiologists, and geneticists, whose research unravels the complicated relationships that plants have with their collaborators and competitors in the natural world.

Schedule for Friday, May 14, 2021 (Eastern Time)
1:00 pm - Welcome
1:10 pm - Leonora Bittleston, "Convergent interactions in carnivorous pitcher plant microcosms"
1:30 pm - Dong Wang, "Indentured servitude: host control of intracellular bacteria in the nitrogen-fixing symbiosis"
1:50 pm - Manuela Dal Forno, "The lichen dilemma: unveiling diversity in multi-species symbioses"
2:10 pm - Panel Discussion

May 14, 2021 01:00 PM in Eastern Time (US and Canada)

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Leonora Bittleston (Boise State University)
Convergent interactions in carnivorous pitcher plant microcosms
The ‘pitchers’ of carnivorous pitcher plants are exquisite examples of convergent evolution. In addition to attracting and digesting prey, they house communities of living organisms. Bittleston asks if these communities also converge in structure or function. Using samples from more than 330 field-collected pitchers of eight species of Southeast Asian Nepenthes and six species of North American Sarracenia, she demonstrates that the pitcher microcosms are strikingly similar. Compared to communities from surrounding habitats, pitcher communities house fewer species. While communities associated with the two genera contain different microbial organisms and arthropods, the species are predominantly from the same phylogenetic clades. Microbiomes from both genera are enriched in degradation pathways and have high abundances of key degradation enzymes. Moreover, in a manipulative field experiment, Nepenthes pitchers placed in a North American bog assembled Sarracenia-like communities.
Dong Wang (University of Massachusetts Amherst)
Indentured servitude: host control of intracellular bacteria in the nitrogen-fixing symbiosis
The nitrogen-fixing symbiosis between legumes and rhizobia carries enormous economic and environmental values. A defining feature of this interaction is the intracellular association of the microsymbiont with its host cell. Wang’s research group is searching for the host determinants that allow the bacteria to enter the host cytoplasm, survive in a membrane-bound compartment, and transform into a nitrogen-fixing organelle. One critical insight from their on-going investigation is that the membrane interface between the bacteria and the host cytosol is an important site for signal and nutrient exchange. The host cell redirects its secretory pathway to deliver onto or across this membrane a variety of important molecules, where they interact with the bacteria directly or indirectly to determine the outcome of this interaction.
Manuela Dal Forno (Fort Worth Botanic Garden | Botanical Research Institute of Texas)
The lichen dilemma: unveiling diversity in multi-species symbioses
Lichens are complex symbiotic units formed by a main fungal partner, a green algal and/or a cyanobacterial partner, along with a diverse community of microorganisms. They represent an important and diverse biological group present in most terrestrial ecosystems, and a main nutritional strategy in Fungi. Despite being classic examples of symbioses, lichens remain broadly unknown systems given its multifaceted interactions and controversial definitions. In this talk, Dal Forno will discuss current concepts in lichenology and utilize her research in the subtribe Dictyonemateae to present examples how diversity of symbiotic fungi and bacteria can shape our understanding of lichens.