Journal Article

A Deficiency at the Gene Coding for ζ-Carotene Desaturase Characterizes the Sunflower <i>non dormant-1</i> Mutant

Alessio Conti, Simonetta Pancaldi, Marco Fambrini, Vania Michelotti, Angelo Bonora, Mariangela Salvini and Claudio Pugliesi

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 4, pages 445-455
Published in print April 2004 | ISSN: 0032-0781
Published online April 2004 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pch052
A Deficiency at the Gene Coding for ζ-Carotene Desaturase Characterizes the Sunflower non dormant-1 Mutant

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The non dormant-1 (nd-1) mutant of sunflower (Helianthus annuus L.) is characterized by an albino and viviparous phenotype. Pigment analysis by spectrophotometer and HPLC demonstrated in nd-1 cotyledons the absence of β-carotene, lutein and violaxanthin. Additionally, we found a strong accumulation of ζ-carotene and, to a lesser extent, of phytofluene and cis-phytoene in nd-1 seedlings grown in very dim light (1 µmol m–2 s–1). These results suggested that ζ-carotene desaturation was impaired in the mutant plants. To understand the molecular basis of the nd-1 mutation, we cloned and characterized the ζ-carotene desaturase (Zds) gene from sunflower. A reconstructed full-length sequence (1,916 bp) of the Zds cDNA was obtained from homozygous Nd-1/Nd-1 wild-type plants. It contains a 1,761-bp CDS, 62 nucleotides of 5′-untranslated region (UTR), and 77 nucleotides of 3′-UTR. The predicted protein (64.9 kDa) consists of 587 amino acid residues with a putative transit sequence for plastid targeting in the N-terminal region and a typical amino oxidase domain that includes the flavin adenosine dinucleotide (FAD) binding motif. The phylogenetic analysis demonstrated that the sunflower Zds was clustered to marigold (Tagetes) Zds gene, for which it showed an overall aminoacidic identity of 96.6% and resulted strictly correlated with other Zds sequences of higher plants. Interestingly, RT-PCR analyses showed that nd-1 plants were unable to accumulate Zds transcripts. Sequence information from the Zds cDNA was used to design specific primers and to isolate the full-length exons/introns region of the gene. The sunflower Zds gene (HaZds) comprises 14 exons and 13 introns scattered in a ca. 5.0-kb region. Also, HaZds showed a high conservation of the distribution and size of the exons with rice Zds gene. Based on genomic Southern analysis, the nd-1 genome disclosed a large deficiency at the Zds locus.

Keywords: Keywords: Carotenoids — Carotenoid biosynthesis gene — Helianthus annuus — Pigment-deficient mutant — RT-PCR — ζ-carotene desaturase.; Abbreviations: ABA, abscisic acid; CrtB, phytoene synthase gene; CRTI bacterial-type phytoene desaturase; CrtI, phytoene desaturase gene; CRTISO, carotenoid isomerase; CrtH, CrtISO, carotenoid isomerase genes; CrtP, phytoene desaturase gene; CrtQa, CrtQb, ζ-carotene desaturase genes; FAD, flavin adenosine dinucleotide; GGPP, geranylgeranyl diphosphate; MEP, 2-C-methyl-d-erythritol 4-phosphate; RACE, rapid amplification of cDNA ends; RT-PCR, reverse transcriptase polymerase chain reaction; PDS, phytoene desaturase; Pds, phytoene desaturase gene; PSY, phytoene synthase; Psy, phytoene synthase gene; WL, white light; ZDS, ζ-carotene desaturase; Zds, ζ-carotene desaturase gene.

Journal Article.  7672 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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