Fructosyltransferase Activities in the Leaf Growth Zone of Tall Fescue.
AUTOR(ES)
Luscher, M.
RESUMO
High concentrations of water-soluble carbohydrates, mainly fructan, accumulate in the growth zone of tall fescue (Festuca arundinacea Schreb.) leaf blades. We studied sucrose-hydrolyzing activities in the leaf growth zone because of their importance in carbohydrate partitioning. Sucrose hydrolysis in the basal 1.5 cm was largely due to fructosyltransferases, which had activities up to 10 times higher than in fully developed leaf tissue. Three fructosyltransferases (F1, F2, and F3) were purified from the leaf growth zone. Each synthesized, from either sucrose or 1-kestose, a mixture of trisaccharides and higher-order oligofructans identical with the low-degree of polymerization fructan extracted from similar plant tissue. The highly purified fructosyltransferases retained ability (13%) to transfer fructose from sucrose to water. Time-dependent and substrate-dependent studies, using sucrose as the substrate, showed proportional production of fructose and glucose, indicating that both products are from the same enzyme. Fructosyltransferase was calculated to contribute about half the total transfer of fructose to water in the basal 1.5 cm. Invertase activity increased to near 2.0 cm when fructosyl transfer to sucrose and other oligofructans decreased. Invertase was the major activity for sucrose hydrolysis at positions distal to 3.0 cm.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=157277Documentos Relacionados
- Nitrogen Use within the Growing Leaf Blade of Tall Fescue.
- Growth Rates and Carbohydrate Fluxes within the Elongation Zone of Tall Fescue Leaf Blades 1
- Response of Fructan to Water Deficit in Growing Leaves of Tall Fescue.
- Diurnal Growth of Tall Fescue Leaf Blades 1: I. Spatial Distribution of Growth, Deposition of Water, and Assimilate Import in the Elongation Zone
- Diurnal Growth of Tall Fescue Leaf Blades 1: II. Dry Matter Partitioning and Carbohydrate Metabolism in the Elongation Zone and Adjacent Expanded Tissue