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Could a genetic tweak give roses back their aroma? Breakthrough may make modern blooms smell like their perfumed ancestors

French scientists have discovered the gene that causes the rose's scent
Modern roses are bred to be tough and look good, rather than for perfume
Switching on the gene that makes an enzyme called called RhNUDX1 could lead to flowers that smell more like their perfumed ancestors

Published: 09:22 EST, 3 July 2015 | Updated: 12:44 EST, 3 July 2015

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Their sweet evocative fragrance is one of the high points of the summer garden.

But roses could smell even sweeter now scientists have discovered the gene that causes the flowers to produce their scent.

It's hoped this breakthrough could restore the flower's formerly more pungent perfume and create flowers that both look and smell good.

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Roses could smell even sweeter (stock image) now scientists have discovered the gene that causes the flowers to produce their scent

Wild roses could not survive without the scent, as no bee would come to visit and pollinate its flower.

But over the years, roses, particularly those bred for the cut flower market have mostly been bred for their visual appearance.

As many roses have to travel hundreds of miles to reach the shops, with many grown overseas, toughness is more important than fragrance.

After all, a rose that smells sweetly but has petals that look wilted and limp is not likely to sell well in florists and, increasingly, in supermarkets and petrol stations.

As a result, the scent of roses has suffered, and become something of an afterthought.

Researchers reveal how flowers make their scent

Experts have identified a gene that ‘switches on’ an enzyme called RhNUDX1, which acts in he cells of the flower’s petals to generate a chemical called monoterpene geraniol (molecule illustrated)

By comparing two roses, Papa Meilland which has a strong fragrance and Rouge Meilland which has very little scent, they found roses make their scents in an unexpected way.

The key was identifying a gene that ‘switches on’ a crucial enzyme called RhNUDX1.

The chemical acts in the cells of the flower’s petals to generate a chemical called monoterpene geraniol, one of the sweetest smelling parts of rose oil.

One of the authors of the research, Philippe Hugueny told the Daily Mail: ‘In cultivated roses, the scent has no reproductive function, it’s only for our pleasure.

Monoterpene geraniol, one of the sweetest smelling parts of rose oil (pictured) and also naturally repels mosquitoes

'So if roses lose its scent it’s too bad. But if a wild rose lost its smell, it would die out.'

It was previously assumed roses produce geraniol in the same way as geraniums – where the scent was first identified.

‘We’ve discovered roses use a totally special pathway to make monoterpenes which at the moment has not been shown in any other plants,’ he said.

Mr Hugueny, of the French National Institute for Agricultural Research (INRA) at Colmar said the development may allow rose breeders to develop roses that look good and smell good – by checking the gene in their roses that produces the enzyme is ‘switched on’ it will make the process much less hit and miss.

There is no market for genetically modified roses in Europe, Mr Hugueny said, but in Japan, where breeders have experimented with GM modifications including creating blue roses, the research might be used.

The research is published in Science.

The chemical Monoterpene geraniol also has the added effect of repelling mosquitos – and is more effective as a repellent than citronella, a commonly used plant based repellent, according to previous research by the Department of Parasitology at the Hebrew University in Jerusalem.

The researchers used diffusers with a concentrated amount of the geraniol to produce the repellent effect, rather than cut roses.

The chemical is found in the scent of many other plants, such as strawberries, which are closely related to roses, and basil.

The researchers will next look at how the scent is produced in these as well.

While the smell of roses is harmless, in industrial quantities, geraniol is classed as a poison.

HOW TO HAVE SWEET DREAMS ... SIMPLY SMELL ROSES

Sweet dreams are made of flowers, according to German researchers.

They say tests have shown that sleeping with roses in your bedroom may provoke pleasant dreams.

During a study in 2008, the scent of the blooms was pumped under the noses of 15 sleeping women for ten seconds over 30 nights.

The volunteers were then woken up and asked to record their dreams - which proved to be more pleasant than normal.

Further analysis showed that the smells had an affect on the emotions of the dreams but did not become part of the dream as women exposed to roses did not dream about roses.

Similar tests showed that the rancid smell of rotten eggs provoked negative feelings in their dreams.

The majority of the sleeping women who were in the rapid eye movement part of their sleep said the eggs had provoked bad feelings in their dream.

The average adult dreams for two hours a night, which adds up to around six years during a person's lifetime.