Studies with 4,6-dioxoheptanoic Acid on etiolated and greening barley leaves

4,6-Dioxoheptanoic acid (DA), an inhibitor of 5-aminolevulinic acid (ALA) dehydratase (EC 4.3.1.24), causes ALA to accumulate at the expense of chlorophyll when applied to greening leaves of Hordeum vulgare L. var. Larker. Preincubating etiolated leaves with DA in darkness eliminates the lag phase in ALA accumulation during a subsequent exposure to illumination. More than 50% of the DA taken up during a 2-hour incubation disappeared during a subsequent 4-hour incubation. These results suggest that barley leaves can metabolize DA, and the products of this metabolism may enhance the capacity for ALA synthesis.