New Zealand Journal of Crop and Horticultural Science abstracts

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Short communication

Brief look at sorbitol in 1-year-old shoots of apple (Malus domestica)

Joanna C. Mcqueen^1,2
Peter E. H. Minchin^2,3

¹Department of Biology
University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: jmcqueen@waikato.ac.nz

²The Horticultural and Food Research
Institute of New Zealand Limited
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand

³ICG-III Phytosphaere
Forschungszentrum Jülich
D 52425 Jülich, Germany

Abstract  The sugar alcohol sorbitol is a major translocatory product in most commercially important species in the Rosaceae family. Sugar alcohols are thought to play a variety of roles in plant tissue, including protecting metabolism during stress. Sorbitol has been found in high concentrations in 1-year-old apple (Malus domestica) shoots, however studies have shown that not all tissue throughout a tree has the ability to metabolise sorbitol. In this study, we looked at sorbitol metabolism in 1-year-old apple shoots using a variety of methods including carbohydrate depletion, metabolism of 14C-sorbitol, and extraction of sorbitol dehydrogenase (SDH), the enzyme necessary to convert sorbitol to fructose. Although starch stores were able to be depleted in the shoot, sorbitol levels increased, corresponding to the decrease in starch, resulting in little net loss of carbohydrate. 14C-sorbitol was not metabolised and no SDH was found in shoot tissue, suggesting that sorbitol has limited metabolism in 1-year-old apple shoots. Sorbitol may thus be ideal for translocation in apple shoot tissue because of its ready movement into the transport pathway, but its restricted utilisation there.

Keywords  apple; sorbitol; SDH; metabolism

H04061; Online publication date 8 March 2005 Received 19 July 2004; accepted 29 November 2004
New Zealand Journal of Crop and Horticultural Science, 2005, Vol. 33: 81–87
0014-0671/05/3301-0081 © The Royal Society of New Zealand 2005

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