Different Patterns of Vein Loading of Exogenous [14C]Sucrose in Leaves of Pisum sativum and Coleus blumei1
AUTOR(ES)
Turgeon, Robert
RESUMO
Vein loading of exogenous [14C]sucrose was studied using short uptake and wash periods to distinguish between direct loading into veins and loading via mesophyll tissue. Mature leaf tissue of Pisum sativum L. cv Little Marvel, or Coleus blumei Benth. cv Candidum, was abraded and leaf discs were floated on [14C]sucrose solution for 1 or 2 minutes. Discs were then washed for 1 to 30 min either at room temperature or in the cold and were frozen, lyophilized, and autoradiographed. In P. sativum, veins were clearly labeled after 1 minute uptake and 1 minute wash periods. Autoradiographic images did not change appreciably with longer times of uptake or wash. Vein loading was inhibited by p-chloromercuribenzenesulfonic acid. These results indicate that uptake of exogenous sucrose occurs directly into the veins in this species. When C. blumei leaf discs were floated on [14C]sucrose for 2 minutes and washed in the cold, the mesophyll was labeled but little, if any, minor vein loading occurred. When discs were labeled for 2 minutes and washed at room temperature, label was transferred from the mesophyll to the veins within minutes. These results indicate that there may be different patterns of phloem loading of photosynthetically derived sucrose in these two species.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1054721Documentos Relacionados
- Enhancement of [14C]Sucrose Export from Source Leaves of Vicia faba by Gibberellic Acid 1
- A Kinetic and Microautoradiographic Analysis of [14C]Sucrose Import by Developing Wheat Grains.
- Tomato Fruit Cell Wall Synthesis during Development and Senescence 1: In Vivo Radiolabeling of Wall Fractions Using [14C]Sucrose
- Compartmentation in Vicia faba Leaves: II. Kinetics of 14C-Sucrose Redistribution among Individual Tissues following Pulse Labeling 12
- Incorporation of [14C]Glucosamine and [14C]Mannose into Glycolipids and Glycoproteins in Cotyledons of Pisum sativum L. 1