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 - 2.05

FATTY ACID PATTERN MODIFICATION IN TRANSGENIC CANOLA AND FLAX DETERMINED BY A RIBOZYME TARGETED TO STEAROYL-ACP DESATURASE RNA

MARINO I., STIGLIANI A.L., SALFI L., GIORIO G., PETROZZA A., D’AMBROSIO C.

Metapontum Agrobios SS. Jonica, Km 448.2, Metaponto (MT) Italy

cdambrosio@agrobios.it

stearoyl-ACP desaturase, hammerhead ribozyme, transgenic oilseed crops

Ribozymes are catalytic RNA molecules capable of cleaving target RNAs in a sequence specific manner. We designed a hammerhead ribozyme able to down-regulate the expression of the stearoyl-ACP desaturase gene in different oilseed species. The ribozyme was tested in vitro on the transcripts of canola, castor bean, flax and sunflower stearoyl-ACP desaturase gene and showed a very high cleavage efficiency for each species. The ribozyme gene was then placed under the control of the 35S CaMV promoter in order to obtain canola and flax transgenic plants. Seed oil compositions of transgenic plants of both species showed statistically significant differences when compared to control plants. In the case of canola, oil of transgenic plants showed a lower level of desaturated fatty acids, and an increase of saturated fatty acids content particularly that of stearic acid which increased of about 50% compared to the control. Strikingly most of the plants presented a drastic reduction of pollen viability which hampered the seed production probably because of the constitutive expression of ribozyme transgene. Also for transgenic flax plants we got an increase in the stearic (up to 60% compared to the control) and oleic acid content and a reduction in the amount of linoleic and linolenic acids. Our results demonstrate that it is possible to project a single ribozyme capable of the specific cleavage of the stearoyl-ACP desaturase transcripts of four species. This ribozyme have showed to be very effective in vitro as well as in the seed of canola and flax transgenic plants where it was able to induce an increase of stearic acid content.

Acknowledgments: This work was partially supported by the Italian Ministry of the University and, Scientific and Technological Research within the Project 4: “Innovazione tecnologica nel sistema agro-industriale: uso delle biotecnologie per lo sviluppo di nuovi prodotti.”