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Carbon pools in low- and high-photorespiratory Hydrilla

Conference · · Plant Physiol., Suppl.; (United States)
OSTI ID:5725939
Differences were found in the internal inorganic carbon (C/sub i/) pools of C/sub i/-starved, low- and high-photorespiratory (PR) Hydrilla leaves exposed to 0.5 mM NaH/sup 14/CO/sub 3/ at high and low external pH. At pH 5 in the light the C/sub i/ level in low-PR plants reached 5.5 mM in 20 s, dropping to a steady-state of 2.5 mM at 60 s. Low-PR plant C/sub i/ levels were twice those of the high-PR. Similar, but lower (50%), trends occurred at pH 9. Fixation of /sup 14/C was similar in both PR states at pH 5, but at pH 9 it was 6-fold greater in low-PR plants. C/sub i/ accumulation occurred in the dark, except in high-PR plants. There was little dark fixation. An internal pH of 8.3 (light) and 8.1 (dark) was found. Calculations indicated that at pH 9 low- and high-PR plants concentrated free CO/sub 2/ 25- and 7-fold, respectively. DCMU incubation decreased /sup 14/C incorporation into the C/sub i/ and fixed fractions by 85% and 75%, respectively, indicating a role for non-cyclic photophosphorylation in C/sub i/ accumulation and photosynthetic fixation. In the dark DCMU caused no inhibition of C/sub i/ accumulation.
Research Organization:
Univ. of Florida, Gainesville
OSTI ID:
5725939
Report Number(s):
CONF-8707108-
Conference Information:
Journal Name: Plant Physiol., Suppl.; (United States) Journal Volume: 83:4
Country of Publication:
United States
Language:
English