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Finding genes that ‘tune’ flower fragrances


February 11, 2010
By Stu Hutson

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Feb. 11, 2010, Gainsville, FL – Shakespeare famously wrote,
“that which we call a rose by any other name would smell as sweet.” With all
due respect to the Bard, University of Florida researchers may have to
disagree: no matter what you call a flower, its scent can be changed. 

Feb. 11, 2010, Gainsville, FL – Shakespeare famously wrote,
“that which we call a rose by any other name would smell as sweet.” With all
due respect to the Bard, University of Florida researchers may have to
disagree: no matter what you call a flower, its scent can be changed.

A team at UF’s Institute of Food and Agricultural Sciences
has uncovered some of the genes that control the complex mixture of chemicals
that comprise a flower’s scent, opening new ways of “turning up” and “tuning” a
flower’s aromatic compounds to produce desired fragrances.

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“For a long time, breeders have mostly focused on how
flowers look, their size, colour and how long blooms last,” said David Clark, a
professor of environmental horticulture. “But scent has gotten left behind. Go
to a florist and try to smell the flowers. You probably won’t get what you
expect.”

Over the years, Clark says, breeders have selected flowering
plants that produce bigger, more attractive flowers with long vase lives; but
in doing so, they may have been inadvertently selecting plants that were
willing to devote less to producing fragrance.

That may change. For example, a customer may someday be able
to walk into a florist and select from scented or unscented varieties of the
same flower.

In work published in the January issue of The Plant Journal
and the February issue of Phytochemistry , the researchers describe how various
genes in petunias help regulate the amount of the 13 major aromatic compounds
in that flower’s fragrance.

The work will help researchers control the levels of these
compounds, adjusting a flower’s fragrance while also producing more or less of
it.

In the papers, the researchers also describe some of the
more fundamental aspects of how flowers produce scent. For example, they
observed that the scents are largely manufactured in the petunia flower’s
petals, and that scent production is activated when the flower opens

u_of_florida_scents

In this file photo, David Clark, University of Florida
professor of environmental horticulture, examines genetically manipulated roses
in a greenhouse on UF’s Gainesville campus. By understanding the genetic
underpinnings of scent, Clark and his colleagues are able to “tune” flower
fragrances without affecting their appearance. (Photo by: Tyler Jones, UF/IFAS)

The studies are part of an ongoing effort to isolate the
chain reaction responsible for producing scent, so that fragrances can be
modified without interfering with other flower qualities, said Thomas
Colquhoun, a UF environmental horticulture researcher and first author on both
papers.

For more than a decade, Clark and his colleagues have combed
through more than 8,000 petunia genes. The search has yielded some interesting
finds.

For example, the gene that produces the compound that gives
rose oil its distinctive scent also makes tomatoes taste good.

By manipulating this gene, UF researchers led by
horticulture professor Harry Klee have been able to create tomatoes with more
flavour. Klee, Clark and colleagues are now working with plant breeders and
taste specialists to prepare the tomato for the marketplace. Better smelling
roses are also in the pipeline.

“The taste of food, the smell of a flower — these are things
that enrich our lives in ways we don’t fully understand yet,” Clark said.
“Learning how plants interact with us and their environment brings us closer to
truly appreciating what the natural world has to offer.”

Stu Hutson is a communications specialist with the
University of Florida.