Blue rose reveals true RNAi colours

The CSIRO has revealed that part of the technology used to develop the blue rose -- unveiled last year by Japanese giant Suntory and its subsidiary, Melbourne company Florigene -- was an RNAi technique developed by CSIRO for gene replacement in plants.

In its first commercial application in plants, the CSIRO-developed RNAi technology was used to inactivate the gene encoding the enzyme dihydroflavonol reductase (DFR) in roses. The enzyme directs the synthesis of red pigments in the flower.

An RNAi molecule which hybridises with the rose DFR gene was used to inhibit the gene's expression. Scientists then inserted Florigene's patented iris DFR gene -- which makes a lot of blue pigment - plus the delphinidin gene from pansy, a gene missing in roses, to produce a blue rose.

The blue rose has yet to gain regulatory approval before it can be commercially grown and marketed.