
%0 Journal Article
%A Broetto, Fernando 
%A Lüttge, Ulrich 
%A Ratajczak, Rafael 
%T Influence of light intensity and salt-treatment on mode of photosynthesis and enzymes of the antioxidative response system of <emph type="2">Mesembryanthemum crystallinum</emph>
%J Functional Plant Biology
%D 2002/01/16
%V 29
%N 1
%P 13-23
%K C3-photosynthesis, catalase, crassulacean acid metabolism, oxidative stress, superoxide dismutase.
%R https://doi.org/10.1071/PP00135
%U https://www.publish.csiro.au/paper/PP00135 
%X The metabolic switch from C3-photosynthesis to crassulacean acid metabolism (CAM),and the antioxidative response of Mesembryanthemum crystallinum L. plants cultured under severe salt stress and high light intensities, and a combination of both stress conditions, were studied. High light conditions led to a more rapid CAM induction than salinity. The induction time was still shortened when both stress factors were combined. A main pattern observed in CAM plants was a decrease in mitochondrial Mn&#8211;superoxide dismutase (SOD) activity during the day. The activities of the chloroplastic Fe&#8211;SOD and cytosolic CuZn&#8211;SOD were increased due to salt treatment after a lag phase, while catalase activity was decreased. Combination of salt and light stress did not lead to a higher SOD activity as found after application of one stress factor alone, indicating that there is a threshold level of the oxidative stress response. The fact that salt-stressed plants grown under high light conditions showed permanent photoinhibition and lost the ability for nocturnal malate storage after 9 d of treatment indicate serious malfunction of metabolism, leading to accelerated senescence. Comparison of CuZn&#8211;SOD activity with CuZn&#8211;SOD protein amount, which was determined immunologically, indicates that the activity of the enzyme is at least partially post-translationally regulated. 
