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

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 1.50

Metabolic engineering of CAROTENOID CONTENT in POTATO (solanum tuberosum) TUBERS

D. PIZZICHINI*, F. MOURGUES**, R. WELSCH***, P. BEYER***, V. PAPACCHIOLI*, R. TAVAZZA*, G. Giuliano*

*) Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), Biotechnology Unit, Casaccia Research Centre, PO Box 2400, Roma 00100AD, Italy

**) Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), Biotechnology Unit, Trisaia Research Centre, 75026 Rotondella (MT), Italy

***) Albert-Ludwigs-Universitat, Institute for Biologie II, 79014 Freiburg, Germany

potato, beta-carotene, antisense

Carotenoids are a class of isoprenoid compounds involved in pigmentation of plants and animal tissues, in light harvesting, and in photoprotection of photosyntetic organisms. In animals, carotenoids are dietary precursors of retinoids, a class of molecules associated with many physiological processes, such as vision (trans-retinal), functionality of mucosal epithelia (vitamin A), morphogenesis (retinoic acid). Carotenoids have antioxidant activities: for this reason they are also thought to prevent some types of cancer .

In order to increase beta-carotene (pro-vitamin A) content in potato tubers we followed two metabolic engineering approaches: a) a push approach, in which early genes of the carotenoid pathway (phytoene synthase, phytoene desaturase) were introduced in sense orientation; b) a stop approach, employing antisense fragments of late genes (lycopene epsilon-cyclase and beta-carotene hydroxylase); both types of transgenes were cloned between the tuber-specific Patatin promoter and the Nos polyadenylation signal. Tubers from from approach b) were characterised through HPLC analysis, which revealed in different lines, an increase of 2-9 fold of ß carotene and important modifications of xanthophyll content. Real time PCR experiments revealed levels of gene silencing ranging from 30% to 70%. Further studies will focus on the characterisation of global transcriptional profiles through DNA microarray analyses.

References

- Giuliano, G., Aquilani, R. and Dharmapuri, S. (2000) Metabolic engineering of plant carotenoids. Trends Plant Sci 5 (10), 406-409.

- Hirschberg, J. (2001) Carotenoid biosynthesis in flowering plants. Curr Opin Plant Biol 4, 210-218.

- Romer, S., Lubeck, J., Kauder, F., Steiger, S., Adomat, C., and Sandmann, G. (2002) Genetic engineering of a zeaxanthin-rich potato by antisense inactivation and co-suppression of carotenoid epoxidation. Metab Eng 4, 263-272.