Diurnal changes in the incorporation of [U- 14C]tyrosine into tocopherols and plastoquinone in leaves of Xanthium strumarium

Abstract

Diurnal changes were found in the pattern of incorporation of [U- 14C]tyrosine into tocopherols and plastoquinone in leaves of Xanthium strumarium. Incorporation of radioactivity into all compounds was at a high level in the early light period, fell to a low value after 4-6 hr before reaching a maximum level after 8-10 hr of light. During the dark period, incorporation into plastoquinone and α-tocopherol was at a low level while that into γ-tocopherol remained high.