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Genetic basis of the hornwort’s carbon-concentrating mechanism
Poster Title: Genetic basis of the hornwort’s carbon-concentrating mechanism
Submitted on 06 Jul 2022
Author(s): Peter Szovenyi et al.
Affiliations: University of Zurich, Humboldt University of Berlin, University of York, University of Munster
This poster was presented at CCM10
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Poster Information
Abstract: Biophysical carbon concentrating mechanisms (CCMs) operating at the single-cell level have evolved independently in various lineages of eukaryotic algae and a single land plant lineage, the hornworts. An essential component for an efficient eukaryotic CCM is a pyrenoid, a specialized compartment inside the chloroplast that mainly comprises the CO2-fixing enzyme RuBisCO. Knowledge on pyrenoid assembly could help to induce its formation in pyrenoid-free plants, potentially increasing photosynthetic efficiency. Information on pyrenoid biology and CCM are primarily available for the unicellular green alga, Chlamydomonas reinhardtii, while very little is known about the molecular mechansisms of pyrenoid assembly and CCM in hornworts.
We investigate the molecular mechanism of CCM using hornworts as a model system. To identify genes potentially ivolved in the hornwort CCM we use a combination of experimental tools including (1) protein co-immuno precipitation of pyrenoid components, (2) identification and localization of candidates homologous to essential CCM genes of Chlamydomonas, and (3) proteomic analyses of whole tissues grown under various stress conditions.
We provide evidence that a potential RuBisCO scaffolding candidate and the RuBisCO co-localizes using fluorescent reporter lines. We further show that the hornwort homolog of the LCIB gene is less intimately linked to the pyrenoid than in Chlamydomonas and localized to the outer thylakoid membranes and/or chloroplast envelop. Finally, we provide evidence that CCM may be inducible by stress and H2O2 treatment in hornworts. Collectively, our results provide the very first molecular insight into the pyrenoid-based CCM of hornworts implying that some molecular mechanisms are potentially similar to those observed in the unicellular alga Chlamydomonas, while others may be unique to hornworts.
Summary: This poster summarizes our efforts to understand the molecular mechanisms of hornwort pyrenoid-based carbon-concentrating mechanisms (CCM)Report abuse »
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