2001-2005 Licence Degree in Plant Sciences, University of Liège, Belgium. Final year research project on the use Bangiophycean red algae as ecological molecular markers to assess anthropogenic eutrophication in the Bay of Calvi, Corsica
Pyrenoid Function and Differentiation in Hornworts (Anthocerotophyta)
Central to my research project are the observations that a pyrenoid (an aggregation of active Rubisco) is found in the chloroplast of many hornworts, and that most pyrenoid-containing species possess a single chloroplast, characters which are not found in any other group of land plants. This suggests that hornworts may have retained genetically heritable algal-like features from the times when plants moved ashore, which were lost in all other terrestrial plants, or alternatively, have independently evolved an analogous mechanism more recently.
The hornwort pyrenoid had been associated with the existence of an active biophysical carbon concentrating mechanism (Smith and Griffiths, 1996), and the CCM activity is correlated with the presence and structure of pyrenoids (Hanson et al., 2002). It has been proposed early land plants probably owe their success to the development of less costly fixation mechanisms involving freely diffusing CO2 to internalised gas exchange surfaces (Griffiths et al., 2004).
My experimental programme starts with physiological methodologies on selected liverworts and hornworts, in order to determine the influence of thallus structure, ventilation and pyrenoid-presence/absence on gas exchange and isotope discrimination characteristics. Next, I will use molecular methodologies to identify essential components of the hornwort pyrenoid. My overall objective is to synthesise my findings into a model of evolution of CCMs in higher green algae and primitive land plants, and to clarify whether the hornwort pyrenoid is ancestral or not.
Griffiths, H., Maxwell, K., Richardson, D., & Robe, W. (2004). Turning the land green: inferring photosynthetic physiology and diffusive limitation in early bryophytes. The Evolution of Plant Physiology. eds AR Hemsley and I Poole, The Linnean Society/Elsevier ISBN 0-12-339552-6 (pp. 3-16).
Hanson, D., Andrews, T. J., & Badger, M. R. (2002). Variability of the pyrenoid-based CO2 concentrating mechanism in hornworts (Anthocerotophyta). Functional Plant Biology, 29, 407-16.
Smith, E. C. & Griffiths, H. (1996). A pyrenoid-based carbon concentrating mechanism is present in terrestrial bryophytes of the class Anthocerotae. Planta, 200, 203-12.
Ministère de la Culture, de l'Enseignement Supérieur et de la Recherche, Luxembourg