Biochemical and Molecular Analysis of Carotenoid Biosynthesis in Flavedo of Orange (Citrus sinensis L.) during Fruit Development and Maturation

Abstract

Changes in carotenoid content and composition and expression of carotenoid biosynthetic genes were analyzed in the flavedo of sweet orange (Citrus sinensis L. Osbeck, cv. Navelate) fruit during development and maturation. Lutein and all-E-violaxanthin were the major carotenoids in chloroplast-containing tissues. During fruit coloration, phytoene, beta-cryptoxanthin, zeaxanthin, and mainly (9Z)-violaxanthin progressively accumulated, and a large proportion of apocarotenoids was also found in the flavedo of full-colored fruits. We have cloned partial and full-length cDNAs corresponding to genes involved in early condensation and desaturase reactions [phytoene synthase (PSY), phytoene desaturase (PDS), and zeta-carotene desaturase (ZDS)], coupled redox reaction (plastid terminal oxidase), cyclizations [beta-lycopene cyclase (beta-LCY) and epsilon-lycopene cyclase (epsilon-LCY)], hydroxylation [beta-carotene hydroxylase (beta-CHX)], and epoxidation [zeaxanthin epoxidase (ZEP)] and analyzed their mRNA accumulation in the flavedo of fruits during development and ripening as compared with those of leaves. Collectively, the results indicated that PDS gene expression correlated with carotenoid content in developing fruit and that up-regulation of PSY and ZDS genes at the onset of fruit coloration would enhance the production of linear carotenes and the flux into the pathway. The shift from the beta,epsilon-branch to the beta,beta-branch of the pathway that originates the changes in carotenoid composition during fruit coloration may be explained by a down-regulation of epsilon-LCY and by the increase of the beta-CHX transcript.

Analysis of Main Quality Characteristics of Persimmon (Diospyros Kaki L.) Fruits.

“…[29]. In addition, the color was well described by a*/b* ratio which was negative for green fruits, zero for yellow fruits, and positive for orange fruits [30]. Alternatively, the color also could be depicted by H° as follows: 0° for reddish-purple, 90° for yellow, 180° for bluish-green and 270° for blue [31,32].…”

Physiology of citrus fruiting

“…For example, it has been shown that chlorophyllase, a constitutively expressed gene, does not increase during natural fruit development (JacobWilk et al, 1999). In addition, the expression patterns of carotenoid biosynthetic genes and an associated abundance of carotenoids during ripening have recently been reported (Kato et al, 2004;Rodrigo et al, 2004;Alós et al, 2006). It is noteworthy that citrus peel contains the greatest diversity of carotenoids of any fruit studied to date and their specific accumulation patterns are responsible for the broad range of colors exhibited by PHYSIOLOGY OF CITRUS FRUITING citrus fruits (Gross, 1987).…”

Comparative Study of the Tissue-Specific Distribution of ABA fromArachis HypogaeaL. and Expression of the 9-CIS Epoxycarotenoid Dioxygenase 1 (AhNCED1) During Plant Development

“…It has also been reported that ABA synthesized in vegetative tissues is translocated to the seeds. The distribution of ABA is an important factor in determining the endogenous concentrations of the hormone at the site of action, and hence, it is an important process in physiological responses (14). It is now well established that ABA in plants is synthesized from carotenoids (C40) and is an apo-carotenoid compound derived from oxidative cleavage of the 11,12 double bonds of 9-cisepoxycarotenoids (18).…”