אסיף מאגר המחקר החקלאי

Functional characterization of CmCCD1, a carotenoid cleavage dioxygenase from melon

Year:

2006

Source of publication :

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Volume :

67

Co-Authors:

Ibdah, M., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Azulay, Y., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Portnoy, V., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Wasserman, B., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Bar, E., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Meir, A., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Burger, Y., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Hirschberg, J., Department of Genetics, The Hebrew University of Jerusalem, Jerusalem, Israel
Schaffer, A.A., Institute of Plant Sciences, The Volcani Center, Agricultural Research Organization, P.O. Box 6, Bet Dagan, Israel
Katzir, N., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Tadmor, Y., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel
Lewinsohn, E., Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel

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Abstract:

Carotenoids are nutritionally important tetraterpenoid pigments that upon oxidative cleavage give rise to apocarotenoid (norisoprene) aroma volatiles. β-Carotene is the predominant pigment in orange-fleshed melon (Cucumis melo L.) varieties, reaching levels of up to 50 μg/g FW. Pale green and white cultivars have much lower levels (0-10 μg/g FW). In parallel, β-ionone, the 9,10 cleavage product of β-carotene, is present (12-33 ng/g FW) in orange-fleshed melon varieties that accumulate β-carotene, and in much lower levels (0-5 ng/g FW) in pale green and white fleshed varieties. A search for a gene putatively responsible for the cleavage of β-carotene into β-ionone was carried out in annotated melon fruit EST databases yielding a sequence (CmCCD1) highly similar (84%) to other plant carotenoid cleavage dioxygenase genes. To test its function, the clone was overexpressed in Escherichia coli strains previously engineered to produce different carotenoids. We show here that the CmCCD1 gene product cleaves carotenoids at positions 9,10 and 9′,10′, generating geranylacetone from phytoene; pseudoionone from lycopene; β-ionone from β-carotene, as well as α-ionone and pseudoionone from δ-carotene. CmCCD1 gene expression is upregulated upon fruit development both in orange, pale-green and white melon varieties, despite the lack of apocarotenoid volatiles in the later. Thus, the accumulation of β-ionone in melon fruit is probably limited by the availability of carotenoid substrate. © 2006 Elsevier Ltd. All rights reserved.

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