Giles Johnson - From Seconds to Seasons – optimising photosynthesis in changing climates

Throughout their life, plants experience major fluctuations in their environmental conditions, especially in light, temperature and water availability. Imbalances between light absorption and photosynthesis can lead to plants experiencing stress, including formation of reactive oxygen species and consequent damage to the cell. Over short time periods, plants adopt a range of protective, regulatory processes which buffer such imbalances by dissipating light energy as heat or by redirecting the flow of electrons. On longer timescales, plants can acclimate photosynthesis, changing the composition of their photosynthetic apparatus to best match the conditions they exper ience.

We are studying both short term regulatory and long term acclimation responses in plants to changes in growth conditions and this talk will present recent findings on aspects of each of these. Over short time scales, we have been examining the functioning of the plastid terminal oxidase (Ptox) as a sink for electron transport in the extremophile brassica Eutrema salsugineum, to understand the mechanisms by which this is able to act as a sink for electron transport under stress conditions. We have recently shown that activation of Ptox requires translocation of the protein within the thylakoid membrane. On a longer time scale, we have been examining photosynthetic acclimation to temperature in Arabidopsis thaliana. We observe that accumulation of fumaric acid, synthesised by the cytosolic fumarase enzyme FUM2, is essential for this acclimation.