Appearance and accumulation of C/sub 4/ carbon pathway enzymes in developing maize leaves and differentiating maize A188 callus
Regenerating maize A188 tissue cultures were examined for the presence of enzymes involved in C/sub 4/ photosynthesis, for cell morphology, and for /sup 14/C labeling kinetics to study the implementation of this pathway during plant development. For comparison, sections of maize seedling leaves were examined. Protein blot analysis using antibodies to leaf enzymes showed a different profile of these enzymes during the early stages of shoot regeneration from callus from the closely-coordinated profile observed in seedling leaves. Pyruvate orthophosphate dikinase (PPDK) (EC 2.7.9.1) and phosphoenolpyruvate carboxylase (PEPC) (EC 4.1.1.31) were found in nonchlorophyllous callus while ribulose 1,5-bisphosphate carboxylase (RuBPC, EC 4.1.1.39) and malic enzyme, NADP-specific (ME-NADP) (EC 1.3.1.37) were not detectable until later. Enzyme activity assays showed the presence of ME-NADP as well as PEPC and PPDK in nonchlorophyllous callus. However, the activities of ME-NADP and PEPC had properties similar to those of the enzymes from C/sub 3/ leaves and from etiolated C/sub 4/ leaf tissues, but differing from the corresponding enzymes in the mature leaf. Immunoprecipitation of in vitro translation products of poly(A)RNA extracted from embryoid-forming callus showed both the 110 kilodalton precursor to chloroplast PPDK and the 94 kilodalton polypeptide. Therefore, the chloroplast tye of PPDK mRNA is present prior to the appearance of leaf morphology. Analysis of the labeled products of /sup 14/CO/sub 2/ fixation by nonchlorophyllous calli indicated ..beta..-carboxylation to give acids of the tricarboxylic acid cycle, but no incorporation into phosphoglycerate. With greening of the callus, some incorporation into phosphoglycerate and sugar phosphates occurred, and this increased in shoots as they developed, although with older shoots the increase in ..beta..-carboxylation products was even greater.
- Research Organization:
- Lawrence Berkeley Lab., CA
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5742264
- Journal Information:
- Plant Physiol.; (United States), Vol. 80:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON CYCLE
ENZYME ACTIVITY
MAIZE
ANTIBODIES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CARBON DIOXIDE FIXATION
CARBOXYLASE
CARBOXYLATION
CHLOROPLASTS
EXPERIMENTAL DATA
LEAVES
MESSENGER-RNA
MORPHOLOGY
NADP
OXIDOREDUCTASES
PHOSPHOTRANSFERASES
PHOTOSYNTHESIS
PLANT CELLS
PLANT GROWTH
POLYPEPTIDES
PRECURSOR
RIBULOSE
RNA
SEEDLINGS
TISSUE CULTURES
TRACER TECHNIQUES
CARBOHYDRATES
CARBON-CARBON LYASES
CARBOXY-LYASES
CELL CONSTITUENTS
CEREALS
CHEMICAL REACTIONS
COENZYMES
DATA
ENZYMES
GRASS
GROWTH
INFORMATION
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
LYASES
MONOSACCHARIDES
NUCLEIC ACIDS
NUCLEOTIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
PENTOSES
PEPTIDES
PHOSPHORUS-GROUP TRANSFERASES
PHOTOCHEMICAL REACTIONS
PLANTS
PROTEINS
REACTION KINETICS
SACCHARIDES
SYNTHESIS
TRANSFERASES
550501* - Metabolism- Tracer Techniques