Enzymatic Formation of β-Citraurin from β-Cryptoxanthin and Zeaxanthin by Carotenoid Cleavage Dioxygenase4 in the Flavedo of Citrus Fruit    

Abstract

In this study, the pathway of b-citraurin biosynthesis, carotenoid contents and the expression of genes related to carotenoid metabolism were investigated in two varieties of Satsuma mandarin (Citrus unshiu), Yamashitabeni-wase, which accumulates b-citraurin predominantly, and Miyagawa-wase, which does not accumulate b-citraurin. The results suggested that CitCCD4 (for Carotenoid Cleavage Dioxygenase4) was a key gene contributing to the biosynthesis of b-citraurin. In the flavedo of Yamashitabeni-wase, the expression of CitCCD4 increased rapidly from September, which was consistent with the accumulation of b-citraurin. In the flavedo of Miyagawa-wase, the expression of CitCCD4 remained at an extremely low level during the ripening process, which was consistent with the absence of b-citraurin. Functional analysis showed that the CitCCD4 enzyme exhibited substrate specificity. It cleaved b-cryptoxanthin and zeaxanthin at the 7,8 or 79,89 position. But other carotenoids tested in this study (lycopene, a-carotene, b-carotene, all-trans-violaxanthin, and 9-cis-violaxanthin) were not cleaved by the CitCCD4 enzyme. The cleavage of b-cryptoxanthin and zeaxanthin by CitCCD4 led to the formation of b-citraurin. Additionally, with ethylene and red light-emitting diode light treatments, the gene expression of CitCCD4 was up-regulated in the flavedo of Yamashitabeni-wase. These increases in the expression of CitCCD4 were consistent with the accumulation of b-citraurin in the two treatments. These results might provide new strategies to improve the carotenoid contents and compositions of citrus fruits.

Effect of blue LED light intensity on carotenoid accumulation in citrus juice sacs

“…TaqMan MGB probes and sets of primers for CitPSY, CitPDS, CitZDS, CitLCYb1, CitLCYb2, CitLCYe, CitHYb, CitZEP and CitVDE were designed according to Ma et al (2013). For endogenous control, the TaqMan Ribosomal RNA Control Reagents VIC Probe (Applied Biosystems) was used.…”

“…In citrus, carotenoids are the pigments responsible for the external and internal coloration of fruits, and their contents and compositions are important indexes for the quality of fruits. In the recent years, the accumulation of carotenoid in fruits of various citrus varieties has been studied, showing that the composition of carotenoid in juice sacs vary greatly among different varieties during the ripening process (Kato et al, 2004;Rodrigo et al, 2004;Rodrigo and Zacarías, 2007;Ríos et al, 2010;Ma et al, 2013;Wei et al, 2014). In Satsuma mandarin (Citrus unshiu Marc.…”

Degreening Buah Jeruk Siam (Citrus nobilis) pada Beberapa Konsentrasi dan Durasi Pemaparan Etilen

“…Pada jeruk Ponkan akumulasi β-cryptoxanthin dan β-citraurin pada kulit buah menghasilkan warna jingga sedangkan violaxanthin menghasilkan warna kuning (Zhou et al, 2010). Perubahan warna kulit jeruk menjadi jingga disebabkan karena terjadinya sintesis karotenoid yang bersifat nonphotosintectic yaitu β-citraurin yang merupakan pembentuk warna jingga kemerahan pada kulit jeruk mandarin, akumulasi senyawa ini ditentukan oleh ketersediaan prekusor berupa karotenoid yang bersifat photosintetic seperti zeaxanthin dan β-cryptoxanthin (Kato et al, 2004;Rodrigo et al, 2013;Ma et al, 2013). …”

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).…”