Two temperature-sensitive photosystem II mutants of pea [fluorescence emission spectra, fluorescence induction kinetics, Pisum sativum]
1980
Stumann, B.M. | Veierskov, B. | Jacobsen, S.-E. | Henningsen, K.W. (Kongelige Veterinaer- og Landbohoeskole, Copenhagen (Denmark). Dept. of Genetics)
Two nuclear gene mutants of pea, chlorotica-887 and chlorina-5756, are temperature-sensitive in the development of photosystem II activity. Low temperature fluorescence emission spectra of leaves show that the peak at 697 nm from the reaction center of photosystem II is present when the mutants have been grown at 18 deg C, but absent when they have been grown at 30 deg C. For leaves of chlorina-5756 grown at 18 deg C the relative size of the peak at 697 nm is reduced compared to that of leaves of the wild type or chlorotica-887 grown at this temperature. Fluorescence induction curves of leaves from wild type plants and chlorotica-887 grown at 18 deg C possess two steps, while those of leaves from chlorina-5756 grown at 18 deg C or 30 deg C and chlorotica-887 grown at 30 deg C show a fast rise to the maximal level of fluorescence. Measurements of chloroplasts isolated from the mutants indicated that the photosystem I activity per g leaf material is comparable for plants grown at 18 deg C and plants grown at 30 deg C. In contrast, no photosystem II activity was detected when the mutants had been grown at 30 deg C. It is suggested that these mutants are affected in a component required for the assembly of functional photosystem II complexes
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