Light-Harvesting for Photosynthesis in Four Strains of the Red Alga Porphyra yezoensis Having Different Phycobilin Contents

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Abstract
The light-harvesting system of photosynthesis was studied in four strains of Porphyra yezoensis differing in their phycoerythrin (PE) content; the red strain, richer in PE than the wild strain, and the green and the yellow strains, poorer in PE. Special attention was given to possible alteration of pigment system in response to PE content, especially in the green and the yellow strains. The relative quantum yields of Chi a fluorescence at − 196°C and O2 evolution were compared. Four strains commonly showed a low yield in pigment system II (PS II) fluorescence on Chi a excitation. The yield was as low as in those algae in which PS II has only a small portion of Chi a as the light harvester. Measurement of O2 evolution gave the same results. Results indicate that the functional composition of Chi a system remains unaltered in four strains with different PE content. PS II in the green and the yellow strains reflects a reduction in the size of light-harvesting components, suggesting that pigmentation in these strains is fixed genetically as a sun-type.