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Physiological Ecology

Head of Group: Professor Howard Griffiths

howard griffithsWe investigate plant molecular, physiological and environmental processes which regulate productivity and CO2 sequestration, and aim to improve the operating efficiency of the primary carboxylase, Rubisco, and match water availability to use. Stable isotope methods are used to evaluate the origins and regulation of diverse photosynthetic carbon concentrating mechanisms (CCM). These include the C4 pathway and Crassulacean Acid Metabolism (CAM), as well as the biophysical CCM in algae and hornworts, where our particular focus is on the molecular determinants of the chloroplast pyrenoid. Our work translates via fieldwork into food security and biomass crop productivity, as well as natural community diversity.

Current projects include:

Defining the algal chloroplast pyrenoid

Molecular interactions control Rubisco packaging into the pyrenoid, and regulate CCM efficiency in the model alga Chlamydomonas, and inform our strategies to re-engineer photosynthesis in crop plants.

Carbon assimilation and hydraulic constraints in C3 systems

Continuity in water flow from stem via leaf to stomata is essential for photosynthetic carbon assimilation and sequestration, whether for crops or the tallest trees. We study mechanisms for maintaining this hydraulic supply.

CAM and C4 productivity and diversity

Ultrastructural and biochemical modifications in CAM and C4 systems (succulence, bundle sheath, CCM) integrate evolutionary origins and energetic demands, which allows us to compare costs and benefits for food and biomass crops.

Epiphyte environmental interactions and climate change

Climate change is threatening fragile ecosystems. We sample bryophytes in Antarctica and the tropical montane (cloud) forests of S. America, the Caribbean and S.E. Asia, using stable isotope hydrology to predict past and future climatic impacts.

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From left: TEM and confocal image of Chlamydomonas reinhardtii with prominent pyrenoid in centre of chloroplast; upper montane rainforest with epiphytes in Trinidad.