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Chlorina mutants (7AL) exhibit not only the decreased chlorophyll content, but also the decreased content of carotenoids (Pettigrew et al. 1969), whose synthesis is not connected with green pigment production. These data combined with the damage of chloroplast ultrastructure suggest that the mutant cn alleles impair the assemblage of thylakoids and grana in chloroplasts rather than the synthesis of W chlorophyll. As a result, the sites for chlorophyll fixation on the membranes appear to be in deficiency. Then, either retro inhibition of the pigment synthesis, or oxidation of the pigments unbound to 'the membrane takes place. The latter suggestion is in accordance with the decrease in a chlorophyll amount caused in chlorina mutants by high light intensity (Klindworth et al. 1995). A weaker (compared to chlorophyll) decrease in the level of the carotenoids resistant to oxidation also confirms the oxidation hypothesis.


References

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