Nature, intracellular distribution and formation of terpenoid quinones in maize and barley shoots.

1. Maize and barley shoots have been shown to contain phylloquinone, plastoquinone, alpha-tocopherol (and gamma-tocopherol in maize), alpha-tocopherolquinone and ubiquinone-9. 2. No solanesol was detected in any tissue examined. 3. In maize shoots plastoquinone and alpha-tocopherolquinone were localized in the chloroplast; ubiquinone was in the mitochondria. 4. Etiolated (dark-grown) shoots contained smaller amounts of phylloquinone and plastoquinone; alpha-tocopherolquinone was entirely absent; ubiquinone and alpha-tocopherol concentrations were unaffected. 5. On illumination of etiolated shoots the chloroplastidic quinones phylloquinone, plastoquinone and alpha-tocopherolquinone were synthesized in step with chloroplast development. alpha-Tocopherolquinone was not formed at the immediate expense of alpha-tocopherol.