[Distribution and relative concentrations of lipophilic plastid quinones in green plants]

The distribution of lipophilic plastid quinones was investigated in green plants of different systematic position. The relative concentrations of plastid quinones, carotenoids and chlorophylls are presented. 1. The lipophilic plastid quinones (plastoquinone 45, α-tocoquinone, α-tocopherol and vitamin K1) have ubiquitous distribution in the photosynthetic apparatus of higher plants and of red, green, brown and bluegreen algae. The photoautotrophic bacteria and the fungi do not contain any of the plastid quinones. 2. The relative concentrations of lipophilic plastid quinones and carotenoids lie within certain standard concentration limits, which are similar for plants of different systematic position. Marked deviations from these concentrations are found in strongly sun-exposed leaves of trees and shrubs, in the older leaves of perennial plants and in the leaves of aurea-variegated plants. 3. Plastinoquinone 45 and α-tocopherol are present in all plants in higher concentrations than α-tocoquinone and the naphthoquinone vitamin K1. In most plants plastoquinone 45 occurs to 50-70% in the reduced form plastoquinol. The lipophilic redox system α-tocoquinone/tocopherol is present in general to 80-90% in the reduced form (α-tocopherol).