Phloem Unloading in Developing Leaves of Sugar Beet: I. Evidence for Pathway through the Symplast
Document Type
Article
Publication Date
9-1-1985
Publication Source
Plant Physiology
Abstract
Physiological and transport data are presented in support of a symplastic pathway of phloem unloading in importing leaves of Beta vulgaris L. (`Klein E multigerm'). The sulfhydryl reagent p-chloromercuribenzene sulfonic acid (PCMBS) at concentration of 10 millimolar inhibited uptake of exogenous [14C]sucrose by sink leaf tissue over sucrose concentrations of 0.1 to 5.0 millimolar. Inhibited uptake was 24% of controls. The same PCMBS treatment did not affect import of14C-label into sink leaves during steady state labeling of a source leaf with14CO2. Lack of inhibition of import implies that sucrose did not pass through the free space during unloading. A passively transported xenobiotic sugar, L-[14C]glucose, imported by a sink leaf through the phloem, was evenly distributed throughout the leaf as seen by whole-leaf autoradiography. In contrast, L-[14C]glucose supplied to the apoplast through the cut petiole or into a vein of a sink leaf collected mainly in the vicinity of the major veins with little entering the mesophyll. These patterns are best explained by transport through the symplast from phloem to mesophyll.
Inclusive pages
237-241
ISBN/ISSN
0032-0889
Publisher
American Society of Plant Biologists
Volume
79
Peer Reviewed
yes
eCommons Citation
Schmalstig, J. G.; Gougler, Judy A.; and Geiger, Donald R., "Phloem Unloading in Developing Leaves of Sugar Beet: I. Evidence for Pathway through the Symplast" (1985). Biology Faculty Publications. 77.
https://ecommons.udayton.edu/bio_fac_pub/77
