|Grennan, Aleel - PLANT BIOLOGY UOFI URBANA|
Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 1998
Publication Date: N/A
Technical Abstract: The decrease in photosynthetic activity in warm-climate plants during exposure to low temperature at high light is a well-documented phenomenon. As measured by changes in chlorophyll fluorescence, this decrease in the chill sensitive species tomato, Lycopersicon esculentum, recovers once the plant is returned to growth conditions. We have observed that concomitant with the inhibition of photosynthesis, there is a decrease in the de novo synthesis of the D1 protein as compared to control plants. The translation of this chloroplast encoded protein is quite likely regulated by the chloroplast redox state. To study the possible interactions between low temperature exposure and chloroplast stroma redox state with respect to D1 synthesis, tomato plants were labeled with [S**35]-methionine and compared over a variety of conditions (high light and low temperature; high light alone; low temperature alone) and levels of newly synthesized thylakoid proteins were monitored. It was shown that there is a decrease in the rate of de novo protein synthesis of D1 in plants exposed to high light and low temperature compared to control plants. Photooxidative methyl viologen treatment of leaves at growth temperature mimicked the effects of the low temperature exposure on the de novo synthesis of D1, further implicating ht possibility of redox control. Northern blot analysis has shown that there is no change in the steady state mRNA levels of psbA, indicating translational control.