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Titre :
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Transport of polyols in higher plants
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Titre original:
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Transport of polyols in higher plants
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Auteurs :
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N. Noiraud ;
L. Maurousset ;
R. Lemoine
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Type de document :
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article/chapitre/communication
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Année de publication :
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2001
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Format :
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717-728
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Langues:
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= Anglais
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Mots-clés:
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mannitol
;
plant
;
polyols
;
sorbitol
;
transport
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Résumé :
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Polyols are reduced forms of aldose and ketose sugars. The most frequently found polyols in plants are mannitol, sorbitol and galactitol as well as the ubiquitous cyclitol, myo-inositol. In contrast to myo-inositol, mannitol and sorbitol are direct products of photosynthesis in mature leaves, in parallel with sucrose. They serve similar functions such as translocation of carbon skeletons and energy between source and sink organs. As the metabolic pathways and functions of polyols have been extensively reviewed during the past years, this review focuses on the most recent data obtained on transport of polyols and discusses some important points regarding membrane transport events. Some polyols are subjected to long-distance transport as shown by their occurrence in the harvested phloem sap. In some species like celery, phloem loading has been shown to occur from the apoplasmic compartment and specific carriers are involved. In Rosaceae, the pathway for transport of polyols has been a matter of debate (apoplastic vs. symplasmic) but some conclusions may have to be reassessed. Increased transport of polyols, both in the phloem and the xylem occurs frequently as a result of salt or drought stress. The recent cloning of a H+/mannitol transporter in celery and putative Na+/myo-inositol transporters in Mesembryanthemum crystallinum are the first steps in a better understanding of polyol transport in plants. (C) 2001 Editions scientifiques et medicales Elsevier SAS.
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Source :
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Plant Physiology and Biochemistry VL 39 NO 9
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