Florigene plans blue rose field trials

Melbourne-based novelty flower developer Florigene is planning the first field trial of its genetically modified roses carrying the company's proprietary 'blue gene' technology.

The nation's gene technology watchdog, the Office of the Gene Technology Regulator (OGTR), announced this week that Florigene has applied for permission to run a small (0.01 hectare) glasshouse-contained field next year of three rose varieties engineered with a pansy transgene that diverts pigment synthesis into the 'blue' delphinidin pathway.

The Florigene trial signals the beginning of a commercialisation process that rose breeders and many rose lovers have been anticipating for more than a century. The world's major rose-breeding companies have invested hundreds of man-years, and millions of dollars, trying to develop a genuinely blue rose by conventional hybridisation.

The quest has yielded novel mauve, lilac, magenta, grey and even brown varieties, but no 'true blue', because the gene that diverts pigment synthesis into the delphinidin pathway does not exist in any of the several hundred wild rose species, or the tens of thousands of varieties developed by interbreeding them.

Florigene's prototype blue roses are not yet 'true blue' but mauve in colour, similar to novelty cultivars like 'Blue Moon' and 'Charles de Gaulle'.

But unlike these famous varieties, Florigene's GM varieties have the potential to found a dynasty of truly blue roses, in hues ranging from palest blue through royal blue to navy blue -- if cultivars can be developed with the right genetic background for the pigment to be expressed in 'true blue' hues.

One of the current stumbling blocks is the natural acidity of rose petals, which shifts hues towards the mauve-lilac spectrum. A more alkaline petal environment would allow full development of blue colours.

Florigene R&D manager Dr John Mason said today the company plans to trial the roses in its own glasshouses when it moves from Collingwood to new and larger premises at the Victorian Agribiosciences Centre near La Trobe University in Bundoora.

The trial will run from March next year until April 2008. It will involve about 100 plants of each of the three cultivars, and a similar number of the non-GM parental lines from which they were developed, for comparative purposes.

Mason said the company had not yet decided whether to release the rose varieties commercially. "The process is that it we get a colour in the laboratory that looks exciting, we will take it through the trialling process and then make a commercial decision down the track," he said.

"We've had rose experts look at them, and we've had mixed comments, some highly technical in nature, relating to the genetic background of the varieties, as much as the colour."

Mason said that, as expected, some rose traditionalists dislike the GM roses; others have shown keen interest. He described the GM cultivars as have a much more solid colour than their conventional mauve counterparts, which tend to look "washed out".

The two floribunda cultivars were developed from the same, well-known parent, while the hybrid tea cultivar was developed from a variety not well known to rose lovers.

No RNAi

Interestingly, two of the roses do not make use of the RNA interference (RNAi) technique developed by CSIRO Plant Industry researchers to selectively knock down the activity of target genes in plants.

Earlier this year, CSIRO announced that researchers with Florigene's parent company, the Japanese distiller Suntory, had used RNAi technology to selectively knock down the endogenous rose gene for dihydrofolate reductates (DFR).

DFR performs the final modification that transforms the colourless pigment precursor dihydrokaempferol (DHK) into cyanidin, the base pigment for deep red, pink and mauve roses.

By installing a different version of the DFR gene, cloned from an iris, to replace the suppressed rose DFR gene, Suntory researchers were able to shut down the endogenous cyanidin pathway, and install the delphinidin pathway.

But Mason said the two floribunda roses did not require RNAi surgery - by pure serendipity, Florigene researchers were able to create a rose in which the DFR transgene simply out-competed the native rose DFR gene because its enzyme has a stronger affinity for the pigment precursor DHK.

Mason said Florigene's major interest was in developing cut flowers for the multi-billion dollar international cut flower market, but is interested in approaches from breeders who would be interested in jointly developing truly blue roses.

The celebrated French hybridists Meilland, breeders of the famous 'Peace' rose, have been seeking to develop a blue rose since the 1930s; so have Dicksons and McGredy's of Ireland, and Germany's Tantau.

Mason agreed that there was intense commercial interest among rose breeders in developing the world's first truly blue roses, but declined to comment on whether Florigene was already negotiating with suitors.

In addition to the pansy DFR gene and the RNAi transgenes used to switch off native rose DFR, the new cultivars also carry an antibiotic-resistance marker gene, used as a selection marker during development of the new GM roses.

The OGTR has called for individuals or organisations that are interested in GM plants to comment in writing on the proposed field trial. It is preparing a Risk Assessment and Risk Management Plan (RARMP) based on expert advice from researchers and stakeholders, and expects to release it for public comment in November.