A high affinity pyruvate decarboxylase is present in cottonwood leaf veins and petioles: A second source of leaf acetaldehyde emission?

Leaves of Populus deltoides emit acetaldehyde under various conditions, and we have discovered that leaf veins and petioles, seen in this image, contain the enzyme pyruvate decarboxylase (PDC), which produces acetaldehyde as a product. We have purified leaf vein PDC 143-fold, and it appears to act as a high affinity PDC, operating under the semi-aerobic conditions occurring in vascular bundles.