PARENT SESSION
Posters P8C C4 and CAM. Abstracts (685-698)

Is Crassulacean acid metabolism a consequence or cause of oxidative stress? Anne Borland^*,1, Stewart Elliott¹, Beata Pater², Jeremy Barnes¹, Tahar Taybi¹, John Cushman³, ¹ Environmental and Molecular Plant Physiology, Newcastle Upon Tyne, Tyneside, UK² Plant Physiology, Cracow, Poland³ Department of Biochemistry, Reno, Nevada, USA

ABSTRACT- The switch to Crassulacean acid metabolism in Mesembryanthemum crystallinum is accelerated by a range of abiotic stressors including salinity, drought, high light, low temperature and anoxia. A common feature of abiotic stressors is the generation of oxidative stress at a cellular level and indeed, the switch to CAM in M. crystallinum is accompanied by increased activities of several anti-oxidative enzymes. However, it is not clear if anti-oxidants are predominantly up-regulated as a direct response to the oxidative stress imposed by salinity or as a consequence of the highly oxidative conditions that develop once CAM is induced. Using gaseous ozone to elicit oxidative stress we have tested the hypothesis that oxidative stress is a key signal for up-regulating the major genes and proteins required for the operation of CAM. By comparing wild-type and CAM-deficient mutants of M. crystallinum we have also started to test the hypothesis that CAM per se imposes specific requirements for anti-oxidants.

KEY WORDS: oxidative stress, PEPC, CAM, ozone