The influence of externally supplied sucrose on phloem transport in the maize leaf strip

摘要: Sucrose (2,5–1000 mmol l−1), labeled with [14C]sucrose, was taken up by the xylem when supplied to one end of a 30-cm-long leaf strip Zea mays L. cv. Prior. The sugar loaded into phloem and transported opposite end, which immersed in diluted Hoagland's nutrient solution. When solution at replaced unlabeled sucrose same molarity as one, two solutions met near middle strip, indicated radioautographs. In dark, translocation 14C-labeled assimilates always directed away from site application, its distance depending on concentration time. applied both ends toward lower concentration. light, transport 14-C-labeled can be (1) morphological base only (light effect), (2) application or (3) independent (basipetal acropetal) direction (sucrose effect). strength sink, represented darkened half reduced applying (at least 25 l−1) strip. However, equimolar do not affect dark sink. Only above 75 l−1 sink effect darnened part reduced. Presumably, increasing replenishes tissue more rapidly, photosynthates illuminated are imported lesser extent