Component of the seco-iridoid and derivatives monoterpenoid indole alkaloids (MIAs, e.g. vincristine, quinine, and strychnine) biosynthesis pathway. Catalyzes two successive and reversible oxidation steps for the formation of 8-oxogeranial from 8-hydroxygeraniol. Active with 8-OH-geraniol, 8-OH-geranial and 8-oxogeraniol in the presence of NAD(+). (6E)-8-hydroxygeranial + NAD(+) = (6E)-8-oxogeranial + H(+) + NADH (6E)-8-hydroxygeraniol + NAD(+) = (6E)-8-hydroxygeranial + H(+) + NADH (6E)-8-oxogeraniol + NAD(+) = (6E)-8-oxogeranial + H(+) + NADH (6E)-8-hydroxygeraniol + NAD(+) = (6E)-8-oxogeraniol + H(+) + NADH Binds 2 Zn(2+) ions per subunit. Alkaloid biosynthesis. Homodimer. Expressed in the leaf internal phloem-associated parenchyma (IPAP) inside the mesophyll. By jasmonic acid (MeJA). Belongs to the zinc-containing alcohol dehydrogenase family. Class-IV subfamily.