Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 5.15

The albino nd-1 mutant of sunflower is impaired at THE z-carotene desaturase step in carotenoid biosynthesis*

CONTI A.*, PUGLIESI C.*^,****, FAMBRINI M.*, MICHELOTTI V.*, PANCALDI S.**, BONORA A.**, SALVINI M.*^,***

*) Università di Pisa, Dip. Biol. Piante Agr. Sez. Genetica, Via Matteotti 1/B 56124 Pisa

**) Università di Ferrara, Dip. delle Risorse Naturali e Culturali, Sez. Sez. Botanica, C.rso Ercole I D'Este 32 44100 Ferrara

***) Scuola Normale Superiore, Piazza dei Cavalieri 7 56126 Pisa

Helianthus annuus, carotenoids, mutant, z-carotene

Carotenoids are isoprenoids essential for all photosynthetic organisms with interesting applications for human health and many industrial products as feed additives, cosmetics and pharmaceuticals. In fungi, bacteria and higher plants the cloning of several carotenogenic genes makes it possible the biotechnological alteration of pathways. Recently, a new carotenoid biosynthesis has been identified (1-Deoxyxylulose-5-phosphate pathway) in bacteria and plants which is responsible for Isopentenyl diphosphate synthesis (IPP), a precursor of Geranylgeranyl diphosphate (GGPP). The conversion of GGPP to phytoene is the first committed step in carotenoid biosynthesis. In plants, phytoene and z-carotene desaturase are required to produce lycopene. It can undergo cyclization and hydroxylation to yield xanthophylls. Several biochemical and molecular informations have been reported for phytoene desaturase but about z-carotene desaturase, the data are more incomplete. This carotenogenic enzyme catalyzes the two desaturation steps to lycopene by introducing two double bounds at position 7,8 of z-carotene and 7’,8’ of neurosporene. To date, the better characterization of the z-carotene desaturase (Zds) gene has been conducted in Capsicum annuum and the vp9 of maize is the first mutant recovered for z-carotene accumulation. Here we report the analysis by HPLC of the carotenoid content in the viviparous nd-1 sunflower mutant (Fambrini et al., 1993), demonstrating that under very dim light, cotyledons and leaves accumulate a high level of z-carotene. The Zds gene of Helianthus annuus has been isolated and we present results on the molecular characterization of nd-1.

Fambrini M., Pugliesi C.., Vernieri P., Giuliano G., Baroncelli S. Theor. Appl. Genet. 87: 65-69, 1993.

* This work was supported by Grant of Scuola Normale Superiore.