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The carotenoid cleavage dioxygenase CCD 2 catalysing the synthesis of crocetin in spring crocuses and saffron is a plastidial enzyme
Author(s) -
Ahrazem Oussama,
RubioMoraga Angela,
Berman Judit,
Capell Teresa,
Christou Paul,
Zhu Changfu,
GómezGómez Lourdes
Publication year - 2016
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13609
Subject(s) - crocetin , crocin , chromoplast , crocus , biochemistry , biology , carotenoid , chemistry , plastid , botany , chloroplast , gene
Summary The apocarotenoid crocetin and its glycosylated derivatives, crocins, confer the red colour to saffron. Crocetin biosynthesis in saffron is catalysed by the carotenoid cleavage dioxygenase CCD 2 ( AIG 94929). No homologues have been identified in other plant species due to the very limited presence of crocetin and its derivatives in the plant kingdom. Spring Crocus species with yellow flowers accumulate crocins in the stigma and tepals. Four carotenoid CCD s, namely Ca CCD 1, Ca CCD 2 and Ca CCD 4a/b and Ca CCD 4c were first cloned and characterized. Ca CCD 2 was localized in plastids, and a longer CCD 2 version, Cs CCD 2L, was also localized in this compartment. The activity of Ca CCD 2 was assessed in Escherichia coli and in a stable rice gene function characterization system, demonstrating the production of crocetin in both systems. The expression of all isolated CCD s was evaluated in stigma and tepals at three key developmental stages in relation with apocarotenoid accumulation. Ca CCD 2 expression parallels crocin accumulation, but C14 apocarotenoids most likely are associated to the Ca CCD 1 activity in Crocus ancyrensis flowers. The specific CCD 2 localization and its membrane interaction will contribute to the development of a better understanding of the mechanism of crocetin biosynthesis and regulation in the chromoplast.