The Metabolic and Developmental Roles of Carotenoid Cleavage Dioxygenase4 from Potato  

Abstract

Dakota 58105-5677 (J.C.S.)The factors that regulate storage organ carotenoid content remain to be fully elucidated, despite the nutritional and economic importance of this class of compound. Recent findings suggest that carotenoid pool size is determined, at least in part, by the activity of carotenoid cleavage dioxygenases. The aim of this study was to investigate whether Carotenoid Cleavage Dioxygenase4 (CCD4) activity affects potato (Solanum tuberosum) tuber carotenoid content. Microarray analysis revealed elevated expression of the potato CCD4 gene in mature tubers from white-fleshed cultivars compared with higher carotenoid yellow-fleshed tubers. The expression level of the potato CCD4 gene was down-regulated using an RNA interference (RNAi) approach in stable transgenic lines. Down-regulation in tubers resulted in an increased carotenoid content, 2-to 5-fold higher than in control plants. The increase in carotenoid content was mainly due to elevated violaxanthin content, implying that this carotenoid may act as the in vivo substrate. Although transcript level was also reduced in plant organs other than tubers, such as leaves, stems, and roots , there was no change in carotenoid content in these organs. However, carotenoid levels were elevated in flower petals from RNAi lines. As well as changes in tuber carotenoid content, tubers from RNAi lines exhibited phenotypes such as heat sprouting, formation of chain tubers, and an elongated shape. These results suggest that the product of the CCD4 reaction may be an important factor in tuber heat responses.

ZEAXANTHIN EPOXIDASE Activity Potentiates Carotenoid Degradation in Maturing Seed

“…In contrast to leaves, in lut1 seed, the total carotenoid level is decreased approximately 75% due to an absence of lutein, and zeinoxanthin and xanthophyll cycle pigment levels are unchanged (Kim et al, 2009). Similarly, divergent impacts in seeds and leaves are observed for other mutations in carotenoid biosynthetic enzymes in Arabidopsis (Tian et al, 2003;Kim et al, 2009) and carotenoid cleavage enzymes in Arabidopsis and potato (Solanum tuberosum; Auldridge et al, 2006;Campbell et al, 2010;Gonzalez-Jorge et al, 2013).…”

Carotenoid Biosynthesis in Arabidopsis: A Colorful Pathway

“…However, this is not always the case. For example, CCD1 and/or CCD4 levels negatively correlate with carotenoid levels in Chrysanthemum and orchid flowers (Ohmiya et al, 2006;Chiou et al, 2010), strawberry fruit (Garcia-Limones et al, 2008), maize endosperm (Vallabhaneni et al, 2010), and potato tubers (Campbell et al, 2010), but not in Ipomea flowers (Yamamizo et al, 2010), citrus fruit (Kato et al, 2006) or rice endosperm (Ilg et al, 2010). In Arabidopsis seeds, carotenoid levels might be controlled by the rate of their degradation by CCD1, since mutant seeds defective in this enzyme show increased carotenoid levels whereas transgenic seeds overexpressing CCD1 display reduced amounts of these pigments (Auldridge et al, 2006b).…”

Novel carotenoid cleavage dioxygenase catalyzes the first dedicated step in saffron crocin biosynthesis

“…Enzymes of the CCD1 family cleave a wide spectrum of different carotenoids at several different positions (9,10; 9,10,9′,10′; 5,6,5′,6′; or 7,8,7′,8′) (11,12). CCD4 enzymes cleave carotenoids at the 9′,10′ or the 7′,8′ positions and determine the level of pigmentation in plant tissues, including Chrysanthemum petals (13), peach flesh (14), potato tubers (15), Citrus peel (16,17), and Arabidopsis seeds (18).…”