Christine Helen Foyer

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Low molecular weight antioxidants, such as ascorbate, glutathione, and tocopherol, are information-rich redox buffers that interact with numerous cellular components. In addition to crucial roles in defense and as enzyme cofactors, cellular antioxidants influence plant growth and development by modulating processes from mitosis and cell elongation to(More)
The discovery that there is a close relationship between ascorbate and glutathione dates from soon after the characterization of the chemical formulae of the two molecules (Szent-Györgyi, 1931; Hopkins and Morgan, 1936). Similarly, it has long been known that thylakoids can generate hydrogen peroxide (H2O2; Mehler, 1951). Following the discovery of(More)
Reactive oxygen species (ROS) have multifaceted roles in the orchestration of plant gene expression and gene-product regulation. Cellular redox homeostasis is considered to be an "integrator" of information from metabolism and the environment controlling plant growth and acclimation responses, as well as cell suicide events. The different ROS forms(More)
Glutathione has numerous roles in cellular defence and in sulphur metabolism. These functions depend or impact on the concentration and/or redox state of leaf glutathione pools. Effective function requires homeostatic control of concentration and redox state, with departures from homeostasis acting as signals that trigger adaptive responses. Intercellular(More)
Photosynthesis is a well-established source of reactive oxygen species (ROS) in plants. The photosynthetic electron transport chain (PET) operates in an aerobic environment; thus, regulatory systems are required to minimize ROS production. Moreover, an efficient antioxidant network is also essential in order to process ROS effectively and to maintain(More)
Ascorbic acid is synthesized from galactono-gamma-lactone (GL) in plant tissues. An improved extraction procedure involving ammonium sulfate precipitation of membrane proteins from crude leaf homogenates yielded a simple, quick method for determining tissue activities of galactono-gamma-lactone dehydrogenase (GLDH). Total foliar ascorbate and GLDH activity(More)
Protoplasts prepared from spinach leaves in May and June contained substantial amounts of ascorbate (1.33±0.28 μmol mg-1 chlorophyll), of which 30–40% was localised in the chloroplasts. During illumination, the ascorbate content was maintained at approximately the same concentration as in the dark in both protoplasts and chloroplasts, even in the absence of(More)
Plants cannot survive without glutathione (γ-glutamylcysteinylglycine) or γ-glutamylcysteine-containing homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of(More)