'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 A HAMMEREAD RIBOZYME CAPABLE OF CLEAVING DIFFERENT DELTA-9 DESATURASE RNA L. STIGLIANI, I. MARINO, D. SALFI, F. CELLINI, C. D’AMBROSIO  Metapontum Agrobios, Metaponto (MT) Italy

Ribozymes are catalytic RNA molecules capable of cleaving target RNAs in a sequence specific manner. We have explored the possibility of using a single hammerhead ribozyme to down-regulate the expression of the ?9 desaturase gene in different plant species. A highly conserved region of the ?9 from eight different oleaginous species was selected in order to design the ribozyme flanking regions (helices I and III). The mismatches between the ribozyme helices and the target gene sequences range from one to six. The ribozyme, tested on the transcripts of canola, castor bean, flax and sunflower ?9 desaturase gene, showed very high in vitro cleavage efficiency for each species. These results demonstrate that the presence of mismatches in the flanking regions of the ribozyme does not affect its catalytic efficacy.