UPTAKE OF GLUCOSE, TREHALOSE AND MANNITOL BY LEAF SLICES OF THE ORCHID BLETILLA HYACINTHINA

SUMMARY Glucose, trehalose and mannitol were all absorbed by leaf slices of the orchid Bletilla hyacinthina. The rates of uptake of trehalose and mannitol were respectively 17.8% and 33.6% of the glucose uptake rate. Absorption of all three carbohydrates was reduced by low temperature or the presence of the inhibitor CCCP. Glucose and trehalose were extensively metabolized within the tissues and 14 C appeared in both ionized and neutral compounds. Of the latter sucrose was the most heavily labelled. In contrast mannitol was scarcely metabolized at all. These results are compared with recently reported experiments on the germination of B. hyacinthina on glucose, trehalose or mannitol.