Inter- and intracellular distribution of amino acids and other metabolites in maize (Zea maysL.) leaves
✍ Scribed by Hendrik Weiner; Hans W. Heldt
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 581 KB
- Volume
- 187
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
In illuminated maize (Zea mays L.) leaves, the distribution of triose phosphates, 3-phosphoglycerate, malate and various amino acids between the chloroplastic and the extrachloroplastic compartments of mesophyll and bundle-sheath cells, and the total vacuolar fraction of the leaves, was determined by a combination of previously published methods, for separating mesophyll from bundle-sheath material, and for nonaqueous subcellular fractionation. The results show that the triose phosphate/3-phosphoglycerate ratio in the extrachloroplastic fraction of the mesophyll cells is about 20-fold higher than in the bundle-sheath cells, which is in accordance with a triose phosphate/phosphoglycerate shuttle postulated previously. Whereas the vacuolar compartment was shown to contain most of the cellular malate, amino acids were found to be almost absent from this compartment. The amino-acid pattern in the extrachloroplastic fraction of the bundle-sheath cells largely resembled the pattern in whole leaves. These results show that for future studies the analysis of amino-acid contents in whole maize leaves can be used as a measure for the amino-acid levels in the cytosol of bundle-sheath cells.