Quantum yields of photosystem II and photosynthesis in an aurea mutant of tobacco (C3) and an oil yellow mutant of maize (C4) which have high capacities for photosynthesis despite low chlorophyll contents
1993
Edwards, G.E. | Johnson, E. | Lal, A. | Krall, J.P.
The quantum yields of O2 evolution, CO2 fixation, and of photosystem II measured by fluorescence analysis, were determined in a mutant of tobacco (C3) and a mutant of maize (C4) having large deficiencies in light harvesting chlorophyll, but having similar capacities for photosynthesis on a leaf area basis as the wild-type plants. The heterozygous dominant mutant of tobacco (aurea, Su/+) having 30% chlorophyll content of the wild-type, and of maize (oil yellow, Oy/+) having 60% chlorophyll content of the wild-type, maintain high leaf absorptances. The maximum O2 evolution on an absorptance basis, measured under limiting red light and saturating CO2 were the same in the mutant versus wild-type plants. Photosystem II measured by fluorescence analysis and CO2 fixation decreased in a similar manner with increasing light intensity, while the ratio of photosystem II measured by fluorescence analysis/ CO2 fixation under varying light remained reasonably constant, in mutant versus wild-type seedlings. The results indicate that these C3 and C4 mutants which have high capacities for photosynthesis despite large deficiencies in chlorophyll content, maintain a high leaf absorptance, and a balanced utilization of absorbed quanta in photochemistry.
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