TRANSPORT OF SUGAR IN PHYTOPHTHORA PALMIVORA (BUTL.) BUTL.

The kinetics of uptake of sucrose, glucose and fructose by Phytophthora palmivora are all biphasic. At low concentrations, glucose and fructose share a common, high-affinity, hexose carrier, and sucrose is probably hydrolyzed extracellularly at these concentrations before the transport of the resultant hexoses by this carrier. At higher concentrations, a low-affinity carrier may transport sucrose directly, but this carrier appears to have a higher affinity for glucose than sucrose. Activity of neutral invertase (β-D-fructofuranoside fructohydrolase) in both soluble and particulate (cell-wall) preparations is considerably in excess of the highest rates of sucrose uptake. [ABSTRACT FROM AUTHOR]