ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The functional organizations of thylakoid membranes from wild type pea (Pisum sativum L. cv. Kapital) and two viable mutants with low chlorophyll (Chl) contents were compared. Nuclear mutations in mutants 7 and 42 led to two- and three-fold decrease in total chlorophyll content, respectively. In spite of low Chl content mutants showed 80% photosynthetic activity, biological productivity, and seed production. It has been shown that mutant membranes differed from that of wild type by Chl distribution between the pigment-protein complexes and by stoichiometry of the main electrontransport complexes. The ratio photosystem I (PSI): photosystem II (PSII): cytochrome (Cyt) bjf complex: Chl was 1:1.1:1.2:650 in wild type chloroplasts, 1:1.8:1.7:600 in mutant 7, and 1:1.5:1.9:350 in mutant 42. PSI- and PSII-dependent electron-transport activities were enhanced in the mutants per mg Chl in proportion to number of reaction centers. The activity of the non-cyclic electron-transport chain increased in proportion to PSII and Cyt bjf complexes. The amount of ATP synthetase per unit of Chl as estimated by H−ATPase activity was much greater in mutant thylakoids, which is favorable for photosynthetic energy transduction. The low content of the light-harvesting complexes (LHC) in mutants is compensated by an increase of the number of PSII and Cyt bjf complexes, which eliminates the bottleneck at the site of plastoquinone oxidation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1996.tb00456.x
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