Journal Article

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

Motohashi, Reiko, Yamawaki, Kazuki, Matsutani, Kazuki, Yahata, Masaki, Matsuta, Asami, Ma, Gang, Wahyudi, Anung, Kato, Masaya, Zhang, Lancui

2013

Overview

In this study, the pathway of β-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 β-citraurin predominantly, and Miyagawa-wase, which does not accumulate β-citraurin. The results suggested that CitCCD4 (for Carotenoid Cleavage Dioxygenase4) was a key gene contributing to the biosynthesis of β-citraurin. In the flavedo of Yamashitabeni-wase, the expression of CitCCD4 increased rapidly from September, which was consistent with the accumulation of β-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 β-citraurin. Functional analysis showed that the CitCCD4 enzyme exhibited substrate specificity. It cleaved β-cryptoxanthin and zeaxanthin at the 7,8 or 7′,8′ position. But other carotenoids tested in this study (lycopene, α-carotene, β-carotene, all-trans-violaxanthin, and 9-cis-violaxanthin) were not cleaved by the CitCCD4 enzyme. The cleavage of β-cryptoxanthin and zeaxanthin by CitCCD4 led to the formation of β-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 β-citraurin in the two treatments. These results might provide new strategies to improve the carotenoid contents and compositions of citrus fruits.

• Publisher: American Society of Plant Biologists
• Subject: beta Carotene - analogs & derivatives / beta Carotene - chemistry / beta Carotene - isolation & purification / beta Carotene - metabolism / beta-cryptoxanthin / BIOCHEMISTRY AND METABOLISM / Biological and medical sciences / Biosynthesis / Carotenoids / Carotenoids - metabolism / Chromatography, High Pressure Liquid / Citrus - drug effects / Citrus - enzymology / Citrus - genetics / Citrus - radiation effects / citrus fruits / color / Complementary DNA / Cryptoxanthins / Dioxygenases - metabolism / DNA, Complementary - genetics / DNA, Complementary - isolation & purification / Enzymes / Ethylenes - pharmacology / Fundamental and applied biological sciences. Psychology / Gene Expression Regulation, Plant - drug effects / Gene Expression Regulation, Plant - radiation effects / Genes, Plant - genetics / Green Fluorescent Proteins - metabolism / Light / Light emitting diodes / Metabolic Networks and Pathways - drug effects / Metabolic Networks and Pathways - genetics / Metabolic Networks and Pathways - radiation effects / Molecular Sequence Data / Nicotiana - drug effects / Nicotiana - genetics / Nicotiana - metabolism / Nicotiana - radiation effects / Pigments / Plant Leaves - drug effects / Plant Leaves - metabolism / Plant Leaves - radiation effects / Plant physiology and development / Plants / Plants, Genetically Modified / Proteins / Recombinant Fusion Proteins - metabolism / Reverse transcriptase polymerase chain reaction / Ripening / Subcellular Fractions - drug effects / Subcellular Fractions - metabolism / Subcellular Fractions - radiation effects / Xanthophylls - chemistry / Xanthophylls - metabolism / zeaxanthin / Zeaxanthins