Heyser W, Evert R F, Fritz E, Eschrich W
Forstbotanisches Institut der Universität Göttingen, Büsgenweg 2, D-3400 Göttingen-Weende, Federal Republic of Germany.
Plant Physiol. 1978 Oct;62(4):491-4. doi: 10.1104/pp.62.4.491.
Following exposure of portions of mature maize (Zea mays L.) leaf strips to (14)CO(2), xylem exudate from the leaf strips contained [(14)C]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 [(14)C]glucose or [(14)C]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 (14)C-labeled sucrose in addition to the (14)C-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.
将成熟玉米（Zea mays L.）叶片条的部分暴露于¹⁴CO₂后，叶片条的木质部渗出液中含有[¹⁴C]蔗糖。蔗糖是通过降低外部压力从叶片条切割表面获得的木质部渗出液中唯一的糖类。木质部渗出液中发现的蔗糖显然是从维管束的自由空间获得的，其浓度高达0.25%。当在黑暗中将[¹⁴C]葡萄糖或[¹⁴C]果糖供应到玉米叶片条的一端时，它们各自被木质部吸收，并运输到另一端。来自此类叶片条的木质部渗出液除了含有¹⁴C标记的己糖外，还含有¹⁴C标记的蔗糖。本研究结果支持这样一种观点，即蔗糖从玉米叶片维管束的质外体装载到伴胞-筛管复合体中。
