Carn the blues: Florigene aiming for horticulture's highest prize

Roses are red, and Melbourne biotech company Florigene wishes that violets were blue -- if they were, it would already have produced horticulture's most elusive prize: the world's first blue rose.

Florigene's R&D director, Dr John Mason, said his company had produced transgenic roses with flower colours corresponding to the mauve-purple-violet hues of the Royal Horticultural Society's colour chart.

"We think they're fantastic" said Mason. "But there are already some roses in these colours. We need to incorporate a number of other things to make a real blue rose."

Mason said he was unperturbed by a media report this week that scientists at Vanderbilt University School of Medicine in San Francisco have found a human liver gene for an enzyme that turns living cells deep blue.

Several years ago Vanderbilt researcher Dr Elizabeth Gillam produced a flask of blue bacteria, using an enzyme extracted from a patient's liver, and the Vanderbilt team is now trying to insert the gene into roses to produce the world's first true blue rose.

Mason said Florigene was aware of the research, and had experimented with a similar approach itself.

Vanderbilt's make-it-blue gene appears to be Cytochrome P450, one of the battery of liver enzymes involved in detoxifying and clearing potentially toxic molecules -- including therapeutic drugs -- from the body.

But the discovery of a potential alternative to Florigene's patented delphinidin gene means the US research team is no further advanced than was Florigene when it embarked on its own blue rose project more than a decade ago. Getting a 'blue' transgene to function in rose petals is no simple, single-gene problem.

Collingwood vs Carlton

In the early 1990s the Collingwood-based company cloned the delphinidin gene from petunia and introduced it into roses, seeking to create a new pigment-synthesis pathway that would open up hues in the range from lightest blue to the dark navy blue of the Collingwood Football Club's rival, Carlton.

Mason said the company had successfully expressed the gene so that the pigment accumulated in the vacuoles of epidermal cells in rose petals. One of the remaining hurdles in the project is that in roses, the vacuole environment is too acidic for petals to develop the desired hues of blue.

"We've tried to manipulate the pH of the vacuole without success, so we're now pursuing other routes, based on our observations of blue-flowered species that have petal pH readings in the same range as roses," he said.

When Victorian agrochemical company Nufarm acquired a controlling interest in Florigene in 2000, it imposed some stringent timelines on the blue rose project, Mason said. Nufarm's group general manager of R&D, Dr Michael Dalling, was CEO of Florigene in the mid-1990s.

"If we do succeed in developing a blue rose, there is plenty of evidence that it will make money," Mason said.

In the meantime, the company's mauve- and purple-hued carnations, the first transgenic ornamental plants to commercialised in Australia, are "going gangbusters" in the cut-flower markets of Japan, and North America, according to Mason.

The carnations for the Americas market are being grown in Ecuador and Colombia.

Mason said Florigene was now marketing larger carnations than the small-flowered commercial varieties it launched in Australia the 1990s, and in a wider range of colours, in accord with consumers' and florists' tastes.

"They're selling very well -- we've produced a very dark, violet variety. Our marketing people think that purples and violets are more popular than any other colour at the moment," he said.

"We're meeting all our sales projections but we're still not selling in Europe. Our original varieties have been approved for sale, but the current regulations Europe is applying to genetically modified crops and foods seem to have been applied to transgenic ornamental plants as well, and the amount of documentation required for marketing approval is growing."

Carnations are not particularly popular in Europe, Mason said, so the company's next project was to develop new mauve, purple and violet varieties of one of the cut flower trade's biggest sellers -- gerberas, already popular for their brilliant colouration.

"Gerberas are potentially a more exciting product than carnations, so we'll see what we can make of them," he said. "We're not looking at any other cut-flower species at this stage. We have limited resources, so we have to focus on getting products onto the market, and on learning what the market wants."

Heaven scent

The next big challenge for flower breeders, Mason believes, will be scent -- scented flowers are in very high demand.

"Meilland, the big French rose breeding company, has been studying floral senescence in roses, and they think that as breeders have selected for longer vase life, they have been selecting for linked genes that don't produce strong fragrance," he said.

According to last week's press report, Israeli researchers have recently compared the genome of the intensely scented rose 'Fragrant Cloud' with that of nearly scentless yellow roses.

The Israelis identified a number of genes unique to the Fragrant Cloud that that may contribute to its intense fragrance -- the brick-red rose features prominently in the parentage of some of the most highly scented modern roses.

Clemson University researcher Dr Sriyani Rajapakse has developed a DNA fingerprinting test for breeders to use to protect their plant variety rights, as well as to track genes for desirable traits in breeding lines.

Rajapakse said biotechnology held great promise for improving roses -- fingerprinting can be used to weed out undesirable traits, as well as to select for traits to improve modern roses.

At the University of Illinois, in Urbana-Champaign, Dr Robert Shirvin hopes to use genetic engineering to remove thorns from roses, a feat already achieved by conventional breeding in blackberries, which are cousins of roses.

"We think this may be the case in roses too. There's a thornless rose out there somewhere," Mason said.