Sugar Transport and Sugar Storage: a Reappraisal of the Importance of Membrane Transport in Sugarcane Performance Ewald

The sucrose storage process of sugarcane has attracted the interest of plant physiologists for 100 years whereby, depending on the availability of techniques and concepts, the biochemical part of enzymology preceded the aspect of compartmentation and transport. With the new techniques of molecular biology and genetic engineering, the manipulation of enzymatic processes has started again, putting the molecular investigation of transport behind. This paper collects examples from research on sugarcane and other plants, which indicate how transport processes can be decisive for growth and sugar storage in plants. The emphasis is on phloem loading, which appears to be limiting in different growth situations throughout the plant's life. For successful genetic improvement of sugarcane, more detailed studies of the biochemical and cytological mechanisms involved in phloem loading are needed. The molecular techniques offer new opportunities not only to change metabolic processes but also to change the transport system and symplastic conductivity.