Abstract
Following exposure of portions of mature maize (Zea mays L.) leaf strips to 14CO2, xylem exudate from the leaf strips contained [14C]sucrose. Sucrose was the only sugar in the xylem exudate which was obtained from the cut surface of the leaf strips by reducing the external pressure. The sucrose found in the xylem exudate apparently was obtained from the free space of the vascular bundles, its concentration amounting up to 0.25%. When [14C]glucose or [14C]fructose was supplied in the dark to one end of a maize leaf strip, each was taken up by the xylem, and transported to the opposite end. Xylem exudate from such leaf strips contained 14C-labeled sucrose in addition to the 14C-labeled hexose. The results of this study support the view that sucrose is loaded into the companion cell-sieve tube complexes from the apoplast of the vascular bundles in the maize leaf.
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- Geiger D. R., Sovonick S. A., Shock T. L., Fellows R. J. Role of free space in translocation in sugar beet. Plant Physiol. 1974 Dec;54(6):892–898. doi: 10.1104/pp.54.6.892. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Giaquinta R. Evidence for Phloem loading from the apoplast: chemical modification of membrane sulfhydryl groups. Plant Physiol. 1976 Jun;57(6):872–875. doi: 10.1104/pp.57.6.872. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Giaquinta R. Phloem Loading of Sucrose: pH Dependence and Selectivity. Plant Physiol. 1977 Apr;59(4):750–755. doi: 10.1104/pp.59.4.750. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sovonick S. A., Geiger D. R., Fellows R. J. Evidence for active Phloem loading in the minor veins of sugar beet. Plant Physiol. 1974 Dec;54(6):886–891. doi: 10.1104/pp.54.6.886. [DOI] [PMC free article] [PubMed] [Google Scholar]