Abstract
Carotenoids exhibit qualitative and quantitative differences, depending on the plant organs and species in which they are expressed. The green tissues of most plants exhibit similar carotenoid profiles and accumulate carotenoids essential for photosynthesis. In contrast, the carotenoid composition of different flowers is distinctive and depends on the plant species. In addition, even within the same plant species, flower petals have a wide range of carotenoid content, from little or none (white petals) to large amounts (yellow petals). At present, however, the understanding of the mechanism that causes such differences is limited. Recently, we showed that in white chrysanthemum petals, carotenoids are synthesized but are subsequently cleaved by CmCCD4a into colorless compounds (Ohmiya et al., 2006). In contrast, most of the carotenogenic gene expression was notably suppressed in the white petals of the Japanese morning glory (Yamamizo et al., 2009). These results suggest that the mechanisms for controlling carotenoid accumulation in flower petals differ among plant species.
