Regulation of pyruvate orthophosphate dikinase gene expression in C/sub 3/ plants as compared to that in C/sub 4/ plants
Pyruvate orthophosphate dikinase (PPDK) was found to be more widely distributed in both leaves and seeds of C/sub 3/ and C/sub 4/ plants than previously realized. Physicochemical and enzymic properties appear to be strongly conserved over this distribution. In wheat, a C/sub 3/ plant, both in seeds and leaves, the amount of PPDK protein is developmentally regulated. In seeds the enzyme level is determined by the level of PPDK mRNA. The role of PPDK seems to be providing phosphoenolpyruvate as a substrate for amino acid interconversions during development. In leaves, the PPDK protein level increased with development. PPDK is present in chloroplasts also in C/sub 3/ plants. In maize, a C/sub 4/ plant, PPDK is not limited to mesophyll cells but also is present in bundle sheath cells, kernels and other tissues. In the leaf, the appearance and accumulation of PPDK is well coordinated with other enzymes of carbon metabolism. In maize callus, a heterotrophic type PPDK is synthesized independently in light and is active in the dark. Shoot formation and establishment of autotrophy enhances the accumulation of the leaf-type PPDK and leaf-type isozymes of phosphoenolpyruvate carboxylase and NADP-malic enzyme. Ultrastructural changes and /sup 14/C uptake patterns during regeneration of leaves from callus indicate that cell differentiation and Kranz anatomy are essential for the functional C/sub 4/ photosynthesis as well as for coordinated expression of enzymes involved in the C/sub 4/ pathway.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 6025901
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LEAVES
CELL DIFFERENTIATION
PHOSPHOTRANSFERASES
TISSUE DISTRIBUTION
AMINO ACIDS
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CHLOROPLASTS
COMPARATIVE EVALUATIONS
GENES
MAIZE
MESSENGER-RNA
PHOTOSYNTHESIS
PROTEINS
SEEDS
TRACER TECHNIQUES
WHEAT
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CEREALS
CHEMICAL REACTIONS
DISTRIBUTION
ENZYMES
GRASS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOTOCHEMICAL REACTIONS
PLANTS
RNA
SYNTHESIS
TRANSFERASES
550201* - Biochemistry- Tracer Techniques