Photosynthetic carbon fixation characteristics of fruiting structures of Brassica campestris L
Activities of key enzymes of the Calvin cycle and C/sub 4/ metabolism, rates of CO/sub 2/ fixation, and the initial products of photosynthetic /sup 14/CO/sub 2/ fixation were determined in the podwall, seed coat (fruiting structures), and the subtending leaf (leaf below a receme) of Brassica campestris L. cv Toria. Compared to activities of ribulose-1,5-bisphosphate carboxylase and other Calvin cycle enzymes, e.g. NADP-glyceraldehyde-3-phosphate-dehydrogenase and ribulose-5-phosphate kinase, the activities of phosphoenol pyruvate carboxylase and other enzymes of C/sub 4/ metabolism, viz. NADP-malate dehydrogenase, NADP-malic enzyme, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, were generally much higher in seed than in podwall and leaf. Podwall and leaf were comparable to each other. Pulse-chase experiments showed that in seed the major product of /sup 14/CO/sub 2/ assimilation was malate (in short time), whereas in podwall and leaf, the label initially appeared in 3-PGA. With time, the label moved to sucrose. In contrast to legumes, Brassica pods were able to fix net CO/sub 2/ during light. However, respiratory losses were very high during the dark period.
- Research Organization:
- Haryana Agricultural Univ., Hisar, India
- OSTI ID:
- 5900356
- Journal Information:
- Plant Physiol.; (United States), Vol. 83:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BRASSICA
CARBON DIOXIDE FIXATION
ENZYME ACTIVITY
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBOXYLASE
ENZYMES
LEAVES
METABOLISM
NUCLEOTIDE DEHYDROGENASES
PHOTOSYNTHESIS
SEEDS
TRACER TECHNIQUES
CARBON-CARBON LYASES
CARBOXY-LYASES
CHEMICAL REACTIONS
FOOD
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LYASES
OXIDOREDUCTASES
PHOTOCHEMICAL REACTIONS
PLANTS
SYNTHESIS
VEGETABLES
551001* - Physiological Systems- Tracer Techniques