Alterations in Carbohydrate Intermediates in the Endosperm of Starch-Deficient Maize (Zea mays L.) Genotypes
- 1 May 1992
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 99 (1) , 146-152
- https://doi.org/10.1104/pp.99.1.146
Abstract
Metabolite levels in kernels of selected starch-deficient mutants of maize (Zea mays L.) were investigated to gain insight into partitioning of carbohydrate metabolism during kernel development. Several free sugars, hexose phosphates, triose phosphates, fructose-2,6-bisphosphate, and pyrophosphate were measured in normal, shrunken, shrunken-2, amylose extender dull waxy, and brittle genotypes, which were in a near-isogenic W64A background. These mutants were selected to include at least one lesion in both the cytosolic (shrunken) and amyloplastic (shrunken-2) compartments. All the starch-deficient genotypes contained elevated levels of fructose-2,6-bisphosphate and triose phosphates but reduced levels of pyrophosphate, indicating an enhanced glycolytic utilization of carbohydrates in response to the reduced utilization of sugars for starch synthesis. The shrunken kernels (sucrose synthase deficient) contained reduced levels of glucose-1-phosphate, glucose-6-phosphate, and fructose-6-phosphate, and this reduction paralleled the reduction in starch accumulation, but levels of triose phosphates were elevated. In shrunken-2 kernels, glucose-1-phosphate, glucose-6-phosphate, and fructose-6-phosphate, dihydroxyacetone phosphate, and glyceraldehyde-3-phosphate were increased, but fructose-1,6-bisphosphate was lower. These findings support the view that hexose phosphate transport across the amyloplast envelope is more important for starch biosynthesis than transport of triose phosphates. The amylose extender dull waxy mutation showed less dramatic effects on hexose phosphates, but the triose phosphates were greatly increased. The brittle mutation, which has an unknown lesion, showed distinctly similar changes in metabolite levels with shrunken-2, suggesting that the lesion may be associated with the amyloplast.Keywords
This publication has 18 references indexed in Scilit:
- Enzymes Catalyzing the Reversible Conversion of Fructose-6-Phosphate and Fructose-1,6-Bisphosphate in Maize (Zea mays L.) KernelsPlant Physiology, 1992
- Sugar Metabolism in Developing Kernels of Starch-Deficient Endosperm Mutants of MaizePlant Physiology, 1990
- Effect of Temperature on Starch Synthesis in Potato Tuber Tissue and in AmyloplastsPlant Physiology, 1988
- Starch Biosynthesis in Developing Wheat GrainPlant Physiology, 1988
- Isolation and Characterization of the Amyloplast Envelope-Membrane from Cultured White-Wild Cells of Sycamore (Acer pseudoplatanus L.)Plant Physiology, 1988
- Enzyme Activities Associated with Maize Kernel AmyloplastsPlant Physiology, 1988
- Ethylene-Induced Increase in Fructose-2,6-Bisphosphate in Plant Storage TissuesPlant Physiology, 1986
- Measurement of the Pyrophosphate Content of Plant TissuesPlant Physiology, 1984
- Measurement of Metabolites Associated with Nonaqueously Isolated Starch Granules from Immature Zea mays L. EndospermPlant Physiology, 1981
- Presence of ADP-Glucose Pyrophosphorylase in Shrunken-2 and Brittle-2 Mutants of Maize EndospermPlant Physiology, 1969