Consequence of absence of nitrate reductase activity on photosynthesis in Nicotiana plumbaginifolia plants
Chlorate-resistant Nicotiana plumbaginifolia (cv Viviani) mutants were found to be deficient in the nitrate reductase apoprotein (NR/sup -/ nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild-type Nicotiana tabacum plants. The grafts of mutant plants were chlorotic compared to the grafts of wild type. Mutant leaves did not accumulate nitrogen but contained less malate and more glutamine than wild leaves. They exhibited a slight increase of the proportion of the light-harvesting chlorophyll a/b protein complexes and a lowering of the efficiency of energy transfer between these complexes and the active centers. After a 3 second /sup 14/CO/sub 2/ pulse, the total /sup 14/C incorporation of the mutant leaves was approximately 20/sup 5/ of that of the control. The /sup 14/C was essentially recovered in ribulose bisphosphate in these plants. It was consistent with a decline of ribulose bisphosphate carboxylase activity observed in the mutant. After a 3 second /sup 14/CO/sub 2/ pulse followed by a 60 second chase with normal CO/sub 2/, /sup 14/C was mainly accumulated in starch which was labeled more in the mutant than in the wild type. These results confirm the observation that in the nitrate reductase deficient leaves, chloroplasts were loaded with large starch inclusions preceding disorganization of the photosynthetic apparatus.
- Research Organization:
- I.N.R.A., Versailles, France
- OSTI ID:
- 6070950
- Journal Information:
- Plant Physiol.; (United States), Vol. 84:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
OXIDOREDUCTASES
ENZYME ACTIVITY
PHOTOSYNTHESIS
NICOTIANA
CARBON 14 COMPOUNDS
CHLOROPLASTS
LEAVES
MUTANTS
NITRATES
NUTRITION
PHYSIOLOGY
PROTEINS
RIBULOSE
STARCH
TRACER TECHNIQUES
CARBOHYDRATES
CELL CONSTITUENTS
CHEMICAL REACTIONS
ENZYMES
ISOTOPE APPLICATIONS
KETONES
LABELLED COMPOUNDS
MONOSACCHARIDES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PENTOSES
PHOTOCHEMICAL REACTIONS
PLANTS
POLYSACCHARIDES
REAGENTS
SACCHARIDES
SYNTHESIS
551001* - Physiological Systems- Tracer Techniques