Abstract
Effects of 3, 3′-dimethyl-4-methoxybenzophenone (NK-049) on the biosynthesis of photosynthetic pigments in higher plant leaves were studied under different light conditions and the following results were obtained: 1) NK-049 completely inhibited the accumulation of both chlorophylls and carotenoids under strong light to yield white seedlings, while an appreciable amount of chlorophylls and carotenoids were accumulated under weak light, which were decomposed rapidly on exposure of the pale green leaves to strong light. 2) Accumulation of protochlorophyllide and its photoconversion to chlorophyllide α in etiolated leaves were not influenced by NK-049, whereas the carotenoid accumulation was strongly inhibited in darkness as well as in the light. 3) Some intermediates involved in the biosynthesis of β-carotene were accumulated in the dark-grown or dim light-grown seedlings. 4) It was concluded that NK-049 specifically inhibits the dehydrogenation process in carotene biosynthesis, which leads to the photodecomposition of chlorophylls under strong light to result in chlorosis.
