Isolation and characterization of cDNAs encoding β-carotene hydroxylase in Citrus

Kim, In-Jung; Ko, Kyong-Cheol; Kim, Chan-Shick; Chung, Won Sang

doi:10.1016/s0168-9452(01)00511-8

Cited by 35 publications

(29 citation statements)

References 19 publications

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“…We detected two cDNA populations based on sequence analysis of the 3# region obtained by RACE-PCR. The finding of two BCH genes in saffron was not surprising, as this has been reported in several plants, including Arabidopsis , tomato (Hirschberg, 1998), pepper (Bouvier et al, 1998), and Citrus (Kim et al, 2001). In tomato, the two enzymes are organ specific; one expressed in green tissue and the other in the flower (Hirschberg, 2001).…”

Section: Discussionmentioning

confidence: 69%

Implications of Carotenoid Biosynthetic Genes in Apocarotenoid Formation during the Stigma Development of Crocus sativus and Its Closer Relatives

2005

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Crocus sativus is a triploid sterile plant characterized by its long red stigmas, which produce and store significant quantities of the apocarotenoids crocetin and crocin, formed from the oxidative cleavage of zeaxanthin. Here, we investigate the accumulation and the molecular mechanisms that regulate the synthesis of these apocarotenoids during stigma development in C. sativus. We cloned the cDNAs for phytoene synthase, lycopene-b-cyclase, and b-ring hydroxylase from C. sativus. With the transition of yellow undeveloped to red fully developed stigmas, an accumulation of zeaxanthin was observed, accompanying the expression of CsPSY, phytoene desaturase, and CsLYCb, and the massive accumulation of CsBCH and CsZCD transcripts. We analyzed the expression of these two transcripts in relation to zeaxanthin and apocarotenoid accumulation in other Crocus species. We observed that only the relative levels of zeaxanthin in the stigma of each cultivar were correlated with the level of CsBCH transcripts. By contrast, the expression levels of CsZCD were not mirrored by changes in the apocarotenoid content, suggesting that the reaction catalyzed by the CsBCH enzyme could be the limiting step in the formation of saffron apocarotenoids in the stigma tissue. Phylogenetic analysis of the CsBCH intron sequences allowed us to determine the relationships among 19 Crocus species and to identify the closely related diploids of C. sativus. In addition, we examined the levels of the carotenoid and apocarotenoid biosynthetic genes in the triploid C. sativus and its closer relatives to determine whether the quantities of these specific mRNAs were additive or not in C. sativus. Transcript levels in saffron were clearly higher and nonadditive, suggesting that, in the triploid gene, regulatory interactions that produce novel effects on carotenoid biosynthesis genes are involved.Carotenoids are terpenoid compounds that are ubiquitous in nature. In all photosynthetic organisms, they carry out essential functions in light-harvesting systems and in photosynthetic reaction centers (Horton et al., 1996). In higher plants, carotenoids play additional roles in providing distinct yellow, orange, and red colors to certain organs, such as flowers and fruits, to attract animals for pollination and dispersal of seeds. In those tissues, unique carotenoids synthesized as secondary metabolites accumulate to high concentrations and are stored within the chromoplasts.All isoprenoids, including carotenoids, are derived from the ubiquitous C5 building blocks isopentenyl diphosphate and dimethylallyl diphosphate. These precursors can be synthesized through two different routes: the classical mevalonate pathway in the cytoplasm or the alternative nonmevalonate pathway in plastids (Rohmer et al., 1993;Arigoni et al., 1997). Metabolic cross-talk between the pathways can be observed under certain conditions (Hemmerlin et al., 2003). The plastidial pathway, now known as the 2-C-methyl-D-erythritol 4-phosphate pathway, has been fully elucidated by a combination of bi...

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Section: Discussionmentioning

confidence: 69%

Implications of Carotenoid Biosynthetic Genes in Apocarotenoid Formation during the Stigma Development of Crocus sativus and Its Closer Relatives

2005

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“…This cluster, encoding a putative protein, was enriched in reads from pool SL but was not granted by the statistical tests. This was also the case for the other two clusters, EGAGLV2214H10.g, enriched in reads from pool LV and encoding an homologue of the pea Cytochrome B6-F complex iron-sulfur subunit (Salter et al, 1992), and EGABST2222G06.g, enriched in reads from pool BK and encoding a protein with high identity to beta-carotene hydroxylases from Citrus unshiu (Kim et al, 2001) …”

Section: Validation Of the In Silico Expression Patternmentioning

confidence: 59%

In silico evaluation of the Eucalyptus transcriptome

et al. 2005

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The expressed sequence tags (ESTs) produced in the Forests project provide an invaluable opportunity to assess the Eucalyptus transcriptome. Besides providing information on the different proteins produced by this plant, it is possible to infer gene expression profiles because non-normalized cDNA libraries were used. The EST frequency from any gene is correlated to the transcript levels in the tissues from which the cDNA libraries were constructed. The goal of this work was to identify Eucalyptus genes that showed either differential expression pattern or were ubiquitously expressed in the tissues sampled in the Forests project. Six robust statistical tests and very restrictive rules were applied to gain confidence in the in silico data aiming to avoid false positives. Several genes with interesting expression profiles were identified and some of them were validated by RT-PCR.

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“…Phytoene synthase (PSY) and β-ring hydroxylase (HYb) are the major enzymes in the metabolic pathway. Transcript levels of PSY increased in the peel and juice sacs at the onset of rind coloration in Satsuma mandarin (Ikoma et al, 2001;Kim et al, 2001). Kato et al (2004) compared the expression level of genes affecting carotenoid content between Satsuma mandarin and 'Valencia' orange during fruit maturation.…”

Section: Introductionmentioning

confidence: 99%

Structure and Expression Levels of Alleles of Citrus Zeaxanthin Epoxidase Genes

Sugiyama

Ikoma

Fujii

et al. 2010

J. Japan. Soc. Hort. Sci.

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The carotenoid metabolism enzyme zeaxanthin epoxidase (ZEP) is a key regulator of carotenoid accumulation in Citrus fruit. The expression level of the gene encoding this enzyme, ZEP, influences varietal differences in the conversion of zeaxanthin to violaxanthin during fruit development. To determine how this gene is regulated, we investigated the structure of its alleles and analyzed allele-specific ZEP expression in heterozygous Citrus fruit. Four independent genomic sequences were isolated from a BAC library of Satsuma mandarin (Citrus unshiu Marc.). All ZEP gene sequences in Satsuma mandarin consisted of 16 exons and 15 introns. Genetic analyses of hybrid populations and analyses of sequence variations identified that two of the sequences were alleles from the ZEP-1/-2 locus, and others were from different locus/loci, ZEP-3/-4, for which allelism has not been confirmed. The ZEP-4 allele was expressed in young-stage fruit, but not in mature-stage fruit, while ZEP-1/-2 alleles were expressed as fruit matured. Our results showed that the newly identified isoform, ZEP-4, did not contribute to the accumulation of violaxanthin during fruit maturation. Expression levels of ZEP-1/-2 alleles in the fruit of three heterozygous Citrus cultivars were compared using allele-specific RT-PCR. Transcripts of ZEP-1 alleles were more abundant than those of ZEP-2 alleles in all three cultivars. Sequence diversity among the 5' UTRs of ZEP alleles was also analyzed. The implications of sequence diversity with respect to diversity of the expression and phylogenetic relationships among ZEP genes in Citrus are discussed.

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Isolation and characterization of cDNAs encoding β-carotene hydroxylase in Citrus

Cited by 35 publications

References 19 publications

Implications of Carotenoid Biosynthetic Genes in Apocarotenoid Formation during the Stigma Development of Crocus sativus and Its Closer Relatives

Implications of Carotenoid Biosynthetic Genes in Apocarotenoid Formation during the Stigma Development of Crocus sativus and Its Closer Relatives

In silico evaluation of the Eucalyptus transcriptome

Structure and Expression Levels of Alleles of Citrus Zeaxanthin Epoxidase Genes

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