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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

SELECTION OF PHOTOAUTOTROPHIC SUNFLOWER CELL CULTURES FOR ALPHA-TOCOPHEROL PRODUCTION

BLANDO F., D’AMICO L., CARETTO S.

Istituto di Ricerca sulle Biotecnologie Agroalimentari - CNR, Via Prov.le Lecce-Monteroni, 73100 Lecce

Fax +39 0832 420000

caretto@irba.le.cnr.it

In vitro production, tocopherol biosynthesis, photoautotrophic cultures, sunflower

The antioxidant tocopherols (vitamin E) represent essential ingredients in human nutrition. Since they are synthesized only by photosynthetic organisms, vegetables are the major source of vitamin E in our food.

With the aim of establishing an efficient and reliable in vitro process for the production of the most active form of tocopherol (alpha-tocopherol), sunflower suspension cultures have been selected for optimal growth rate and increased tocopherol yield. Due to the occurrence of tocopherol biosynthesis in chloroplasts of higher plants, efforts have been made in order to establish photoautotrophic sunflower cell cultures. Photoautotrophic cultures are able to grow in a mineral salt solution without sucrose in the presence of a CO₂ enriched atmosphere and a sufficient supply of light. They provide a very useful tool for studies dealing with metabolic pathways which require intact chloroplasts. Starting from a well characterized sunflower suspension culture growing in the presence of 30 g/L sucrose, a serial selection has been carried out for cell cultures able to grow with reduced sucrose supply (10 g/L) and continuous light. Growth rate, chlorophyll content and alpha-tocopherol production have been evaluated in comparison with unselected cells. For establishing photoautotrophic sunflower cell cultures, the sucrose concentration has been further reduced (5 and 2 g/L) and carbon dioxide (2% v/v) has been supplied by using the two-tier culture flask system (KHCO₃/K₂CO₃ buffer). The evaluation of viability and growth rate of subsequent generations is in progress in the selected cells.