This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (32) Citing Articles via Google Scholar Google Scholar Articles by Davis, J. M. Articles by Loescher, W. H. Search for Related Content PubMed PubMed Citation Articles by Davis, J. M. Articles by Loescher, W. H. Agricola Articles by Davis, J. M. Articles by Loescher, W. H.

Metabolism and Enzymology

Biosynthesis of Sucrose and Mannitol as a Function of Leaf Age in Celery (Apium graveolens L.) ¹

Department of Horticulture and Landscape Architecture, Washington State University, Pullman, Washington 99164-6414

In celery (Apium graveolens L.), the two major translocated carbohydrates are sucrose and the acyclic polyol mannitol. Their metabolism, however, is different and their specific functions are uncertain. To compare their roles in carbon partitioning and sink-source transitions, developmental changes in ¹⁴CO₂ labeling, pool sizes, and key enzyme activities in leaf tissues were examined. The proportion of label in mannitol increased dramatically with leaf maturation whereas that in sucrose remained fairly constant. Mannitol content, however, was high in all leaves and sucrose content increased as leaves developed. Activities of mannose-6-P reductase, cytoplasmic and chloroplastic fructose-1,6-bisphosphatases, sucrose phosphate synthase, and sucrose synthase increased with leaf maturation and decreased as leaves senesced. Ribulose bisphosphate carboxylase and nonreversible glyceraldehyde-3-P dehydrogenase activities rose as leaves developed but did not decrease. Thus, sucrose is produced in all photosynthetically active leaves whereas mannitol is synthesized primarily in mature leaves and stored in all leaves. Onset of sucrose export in celery may result from sucrose accumulation in expanding leaves, but mannitol export is clearly unrelated to mannitol concentration. Mannitol export, however, appears to coincide with increased mannitol biosynthesis. Although mannitol and sucrose arise from a common precursor in celery, subsequent metabolism and transport must be regulated separately.

¹ Supported in part by the National Science Foundation, Grant DMB-8604100. Scientific Paper No. 7688. College of Agriculture and Home Economics, Agricultural Research Center, Washington State University, Pullman, WA 99164-6242.

This article has been cited by other articles:

				B. Pommerrenig, F. S. Papini-Terzi, and N. Sauer Differential Regulation of Sorbitol and Sucrose Loading into the Phloem of Plantago major in Response to Salt Stress Plant Physiology, June 1, 2007; 144(2): 1029 - 1038. [Abstract] [Full Text] [PDF]

				N. Noiraud, L. Maurousset, and R. Lemoine Identification of a Mannitol Transporter, AgMaT1, in Celery Phloem PLANT CELL, March 1, 2001; 13(3): 695 - 705. [Abstract] [Full Text]

				Z. Gao and W. H. Loescher NADPH Supply and Mannitol Biosynthesis. Characterization, Cloning, and Regulation of the Non-Reversible Glyceraldehyde-3-Phosphate Dehydrogenase in Celery Leaves Plant Physiology, September 1, 2000; 124(1): 321 - 330. [Abstract] [Full Text]

				N. Noiraud, S. Delrot, and R. Lemoine The Sucrose Transporter of Celery. Identification and Expression during Salt Stress Plant Physiology, April 1, 2000; 122(4): 1447 - 1456. [Abstract] [Full Text]