Products of fermentation in the roots of alders (Alnus Mill.)

The aim of this work was to discover the products of carbohydrate fermentation in alder roots. Experiments were done with roots of trees growing in naturally wet soils. Detached, anaerobic roots accumulated ethanol, and ethanol was the major labelled product of metabolism of [U-(14)C]sucrose. Glycerol was not labelled from [U-(14)C]sucrose, and did not accumulate in detached or attached roots. In both winter and summer, roots in the field contained little or no glycerol, and the amount was less than that in the aerobic parts of the tree. Roots in the field contained substantial amounts of ethanol. We conclude that ethanol is the major product of fermentation in alder roots, and that glycerol is not a significant product. These results are not consistent with Crawford's metabolic theory of flooding tolerance.