Author:
Broetto Fernando,Lüttge Ulrich,Ratajczak Rafael
Abstract
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–superoxide dismutase (SOD) activity during
the day. The activities of the chloroplastic Fe–SOD and cytosolic
CuZn–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–SOD activity with
CuZn–SOD protein amount, which was determined immunologically, indicates
that the activity of the enzyme is at least partially post-translationally
regulated.
Subject
Plant Science,Agronomy and Crop Science
Cited by
58 articles.
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