Pigment Biosynthesis II: Betacyanins and Carotenoids

Analysis of carotenogenic gene expression in petals and leaves of carnation (Dianthus caryophyllus L.)

“…There was an inverse correlation between NCED1 expression and total carotenoids during petal development. However, it does not seem that NCED1 is directly responsible for regulating the total carotenoid content in petals because NCED acts only on 9-cisepoxycarotenoids, which are generally minor carotenoid components in plant tissues (Schwartz et al 1997, Ohmiya 2011. From these results, we hypothesize that the low level of carotenoids in carnation petals was caused not by their enzymatic degradation but by low rates of carotenoid biosynthesis.…”

“…The green tissues of most plants have similar carotenoid profiles: carotenoids that are essential for photosynthesis, such as lutein, b-carotene, violaxanthin and neoxanthin, are invariably found. In contrast, the carotenoid composition in petals differs among plant species (Ohmiya 2011). The carotenoids found in leaves and petals are designated chloroplast-and chromoplasttype carotenoids, respectively (Yamamizo et al 2010).…”

“…The major pigments that accumulate in plant petals are anthocyanins and carotenoids, producing blue-to-red and yellowto-red colours, respectively. However, petal colours of most plants in the order Caryophyllales are derived from neither anthocyanins nor carotenoids but instead from betalains, yellowto-red nitrogen-containing compounds (Clement andMabry 1996, Sakuta andOhmiya 2011). Plants in the families Caryophyllaceae and Molluginaceae are exceptions that produce petal colours with flavonoids, including anthocyanins (Mato et al 2000, Itoh et al 2002, Matsuba et al 2010.…”

“…In the past decade, nearly all of the carotenogenic genes in plants have been identified (Cunningham and Gantt 1998, Tanaka et al 2008, Sakuta and Ohmiya 2011. However, the mechanisms that control carotenoid biosynthesis and accumulation in plants are largely unknown.…”

Comparative Analysis of Two DOPA Dioxygenases from Phytolacca americana

“…Although anthocyanins are broadly distributed among higher plants as flower and fruit color, betacyanins have replaced anthocyanins in the Caryophyllales, with the exception of the families Caryophyllaceae and Molluginaceae [2]. The anthocyanin biosynthetic pathway is one of the best studied examples of secondary metabolism in higher plants, but the biochemistry and genetics of the betalain biosynthetic pathway remain relatively uncharacterized [3][4][5]. Extensive studies of the biosynthetic reactions of betalains led to the discovery of several enzymes that function in early betalain biosynthesis, including polyphenol oxidase-type tyrosinase [6.7] and extradiol DOPA dioxygenase (DOD) [8,9].…”