Carbohydrate metabolism in biotrophic plant pathogens.

Sucrose is the major carbon source in vivo. It is hydrolysed by extracellular fungal invertases and the hexoses taken up by proton symport. They are rapidly metabolized to hexitols as the endproduct of the uptake process. In further metabolism, in which pentitols are accumulated, fructose-6-phosphate has a central role.