Invertases. Primary Structures, Functions, and Roles in Plant Development and Sucrose Partitioning

Extract

One of the key features of plants is their ability to reduce carbon dioxide in the presence of sunlight and water to sugars, and the subsequent transport of assimilated carbon to the nonphotosynthetic tissues (sink tissues). In most plants, the transported sugar is Suc, a nonreducing disaccharide, in which Glc and Fru are linked (α1→β2). Depending on the physiological activities and the biochemical needs of the heterotrophic tissues, Suc is channeled into various pathways in different subcellular compartments. It may enter glycolysis and the tricarboxylic acid cycle for the production of ATP and NADH. The carbon of the disaccharide may also be used for the biosynthesis of primary metabolites important for tissue growth and development. Likewise, Suc may become converted into polymers such as starch, triacyl glycerides, or polypeptides for long-term storage, or into secondary compounds, enabling plants to cope with predators and pests or other environmental challenges. Many of these processes may take place in the same cell at the same time and, thus, allocation of Suc to these different processes requires efficient and precise control mechanisms.