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 - 3.20

SELECTION OF SUNFLOWER CELL CULTURES WITH IMPROVED ALPHA-TOCOPHEROL BIOSYNTHESIS

C. FACHECHI, R. GALA, G. ZACHEO, S. CARETTO

Istituto di Scienze delle Produzioni Alimentari, Sezione di Lecce, CNR, Via Prov.le Lecce-Monteroni 73100 Lecce, Italy

vitamin E, in vitro production, tocopherol, chlorophyll, sunflower

Tocopherols (vitamin E), one type of antioxidant phytochemicals in plants, are known to prevent degenerative disease processes in humans. One particular form, alpha-tocopherol, is the most biologically active component of vitamin E and is synthesised in its effective form only by photosynthetic organisms. Vegetable oils and, to a lesser extent, vegetables are the main dietary sources of alpha-tocopherol.

In plants, alpha-tocopherol acts mainly as a highly efficient recyclable chain reaction terminator for the removal of the polyunsaturated fatty acid free radicals, which are generated during lipid peroxidation. The biosynthesis of alpha-tocopherol occurs in chloroplasts of higher plants where it is especially localised.

Using sunflower cell cultures, growing in heterotrophic conditions, an in vitro system for the biotechnological production of natural alpha-tocopherol was established.

Among the obtained sunflower cell cultures, two suspension cell lines having different levels of alpha-tocopherol were identified: one cell line (HT - High Tocopherol) had an almost 3-fold higher tocopherol level than the other (LT – Low Tocopherol). The chlorophyll content was analysed in both lines resulting significantly increased in HT cells compared to LT cells. Cytological evidences revealed the presence of a higher number of chloroplasts in HT cells than in LT. The ability to grow in the presence of reduced sucrose concentration (mixotrophic conditions) was tested for both cell lines. While LT cells could not survive with a reduced exogenous carbon source, HT cells not only could cope with the sucrose-stress but also showed an improved ability to biosynthesise both chlorophyll and alpha-tocopherol. The cell growth time course of HT growing in mixotrophic conditions is in progress and will help discussing the efficiency of this system for the biotecnhological production of alpha-tocopherol.