Malic acid accumulation in roots in response to flooding: Evidence contrary to its role as an alternative to ethanol

Across a time course of flooding the malic acid content in roots of the swamp tree Nyssa sylvatica var. biflora increased 5-fold from 1 week to 1 month of flooding and remained at that level through a full year of flooding. Alcoholic fermentation rates accelerated within the first month of flooding but dropped to very low levels under long-term flooding. The theory that, under flooding, malic acid accumulates as an alternative anaerobic end product to ethanol is unlikely in this instance since (1) malate is initially associated with high alcoholic fermentation and (2) the reduction in alcoholic fermentation is accounted for by increased internal aeration of the roots.