Photosynthesis
Prof P Horton FRS
The Horton lab is investigating the molecular mechanisms which regulate the structure and function the photosynthetic membrane. The approach is multidisciplinary, combining biochemical and structural analysis of purified proteins with spectroscopic, physiological and genetic analyses of intact systems. In order to maximise their use of light energy in photosynthesis, plants have light-harvesting antennae, which collect light quanta and deliver them to the reaction centres, where energy conversion takes place. The functioning of the antenna responds to the extreme changes in the intensity of sunlight encountered in nature. In shade, light is efficiently harvested in photosynthesis. However, in full sunlight, much of the energy absorbed is not needed and we have shown how vitally important switches to specific antenna states safely dissipate the excess energy as heat. This is essential for plant survival because it provides protection against the potential photo-damage of the photosynthetic membrane. In addition to striving to elucidate the molecular mechanisms of photopotection, we have sought to explore its relationship to the productivity of major crop species, rice and bean.
More detailed information on the research interests of the Horton group is given via the link to the Horton Lab WebPages.
Photoprotective switching to specific antenna states depends upon the precise macro-oroganisation of LHCII in the PSII supercomplex (left), and results from changes in the configuration of pigments bound to each LHCII molecule (right).
Arabidopsis thaliana (left) is used as a model plant to explore the roles of specific pigments and proteins in photoprotection. Then, through collaboration with international agricultural centres, this knowledge is then applied to the study of major crop plants, such as rice (right) growing in its native environment.
Selected Publications
Davison P, Hunter CN, Horton P (2002). Overexpression of beta-carotene hydroxylase enhances stress tolerance in Arabidopsis. Nature 418: 203-206. Ruban AV, Wentworth M, Yakushevska AE, Andersson J, Lee PJ, Keegstra W, Dekker JP, Boekema EJ, Jansson S, Horton P (2003). Plants lacking the main light harvesting complex retain PSII macro-organisation. Nature 421: 648-652. Murchie EH, Hubbart S, Peng S, Horton P (2005). Acclimation of photosynthesis to high irradiance in rice: gene expression and interactions with leaf development. Journal of Experimental Botany 56: 449-460. Pascal AA, Liu Z, Broess K, van Oort B, van Amerongen H, Wang C, Horton P, Robert B, Chang W, Ruban AV (2005). Molecular basis of photoprotection and control of photosynthetic light-harvesting. Nature 436: 134-137. Horton P, Wentworth M, Ruban AV (2005). Control of the light harvesting function of chloroplast membranes: the LHCII-aggregation model for non-photochemical quenching. FEBS Letters 579: 4201-4206. Wentworth M, Murchie EH, Gray JE, Villegas D, Pastenes C, Pinto M, Horton P. (2006). Differential adaptation of two varieties of common bean to abiotic stress. II. Acclimation of photosynthesis. Journal of Experimental Botany 57: 699-709. Ruban AV, Solovieva S, Lee PJ, Ilioaia C, Wentworth M, Ganeteg U, Klimmek F, Chow WS, Anderson JM, Jansson S, Horton P. (2006). Plasticity in the composition of the light harvesting antenna of higher plants preserves structural integrity and biological function. Journal of Biological Chemistry 281: 14981 - 14990.