Comparative Studies on Plastoquinones: V. Changes in Lipophilic Chloroplast Quinones during Development.

Changes of lipophilic chloroplast quinones in corn, oats, peas, and Vicia faba are reported after 0, 4, 8, 12, 16, 20, 24, 48, 72, or 96 hours of exposure to light. There is a pronounced increase in plastoquinone A and chlorophyll levels and slight increase, in plastoquinone C(1-6), vitamin K(1), and alpha-tocopherylquinone content. Coenzyme Q levels, on the other hand, show little change upon exposure to light.THE SEQUENCE IN WHICH INDIVIDUAL QUINONES APPEAR DURING DEVELOPMENT IS AS FOLLOWS: plastoquinone A instantaneously after exposure to light, plastoquinone C(1-6) from 4 to 24 hours, vitamin K(1) from 12 to 24 hours, alpha-tocopherylquinone from 0 to 24 hours of illumination. Small amounts (<0.01 mumole/g, dry wt) of plastoquinone A and plastoquinone B are found in seeds and etiolated tissues. After exposure to light, the quinone tentatively identified as a member of the plastoquinone B series by reverse phase thin layer chromatography disappears and can be detected again in small amounts during maturity and toward senescence of the leaf.