GENET archive

[Index][Thread]

SCIENCE: Israeli scientists enhance food with the scent of flowers



                                 PART I
------------------------------- GENET-news -------------------------------
TITLE:  A sweet smell - Israeli scientists enhance food with the scent of
        flowers
SOURCE: Israel21c, USA
AUTHOR: Nicky Blackburn
URL:    http://www.israel21c.org/bin/en.jsp?enDispWho=Articles%
5El1627&enPage=BlankPage&enDisplay=vi
ew&enDispWhat=object&enVersion=0&enZone=Technology
DATE:   22.04.2007
--------------------------------------------------------------------------


A sweet smell - Israeli scientists enhance food with the scent of flowers

Prof. Alexander Vainstein is proud of his greenhouses. Located at the
Hebrew University's Robert H. Smith Institute of Plant Sciences and
Genetics in Agriculture in Rehovot, these greenhouses offer visitors
both a delight to the senses, and a trip to a futuristic world where
flowers emerge in different colors, with different scents, and a whole
new genetic make-up designed to enhance and improve the flower stock.

"You'll see types of flowers in our greenhouses that do not exist
anywhere else in the world," says Vainstein, the head of the institute,
with satisfaction. "People are stunned at what we are doing here. We
have petunias, which traditionally don't have a smell, giving off such a
strong perfume that it overpowers you as you walk through the greenhouse
doors."

The greenhouses are only a small part of Vainstein's work, however. Back
in the lab, he and other researchers from the Faculty of Agricultural,
Food and Environmental Quality Sciences have discovered how to insert
the scent of flowers into different foods, how to intensify the smell of
perfumes and creams, and how to create a natural scent with nothing more
than a Petri dish.

The developments, which use the same genetic engineering techniques
developed in the human genome project to enhance the shape, color and
smell of flowers, have generated a great deal of interest from the
chemical, food and flower industries, which are not only following
developments, but often actively funding the work.

Vainstein, a molecular biologist, began studying the molecular mechanism
of scent compounds in flowers out of curiosity. "Until recently, people
knew very little about the genetic mechanism of scent production," he
explained to ISRAEL21c. "We just wanted to understand how it works.
Smell is a very volatile thing. Flowers smell differently at different
times of the day, it depends if it's hot or cold, or whether the flower
is young and old. Some plants give off strong scents, while others you
have to crush before you can smell them."

Once the team isolated and deciphered the composition of genes and
proteins operating in the petals of roses and carnations, they began to
genetically engineer the plants to alter scent production. Roses, for
example, give off a strong and lovely scent, and have major volatile
scent compounds such as germacrene D. Vainstein took the gene
responsible for this compound in roses, and inserted it into different
plant species such as petunias and carnations.

"This means that the petunia now produces scent compounds found normally
in roses. It's not that the petunias now smell of roses, but they do
give off a much stronger scent than before," says Vainstein. "They smell
differently. It creates a new pallet. Take a lemon and a rose, for
example, they have a lot of similar scent compounds, but it's the small
differences that make all the difference."

In another successful project, the researchers took a gene from a small
aromatic plant that grows in California and introduced it to the
carnation plant, which now produces the same aromatic compound as the
California plant. At the same time, they've also discovered how to mute
scent in flowers, such as gypsophelia (baby's breath) - a flower often
favored by florists in bouquets - which have an unpleasant odor.

The possibilities for the plant breeding industry are exciting. The
flower industry is worth $20.8 billion in 2006 in the US alone, and more
than $100 billion worldwide. Many flowers sold by florists today have
lost their smell. Vainstein's research promises to be able not only to
regenerate that smell in flowers like roses, but also to create entirely
new scents in other flowers.

What interests the chemical and food industries, however, is that the
researchers have also discovered a way to introduce these volatile scent
compounds into other organisms, such as yeast - which has many
similarities to plants - to create a bioreactor to product these natural
compounds.

"In Bulgaria the economy is built heavily on rose oil which they produce
from roses grown over large areas, but it's a very long and complicated
process to create this oil," said Vainstein. "We can produce the same
scent compounds using a yeast bioreactor and we do it in a Petri dish.
We use a tiny amount of space. A few shelves can hold row after row of
Petri dishes, and there is no disease, no worries about weather or
pests, and a drastic reduction in manpower costs. The value for the
perfume industry is immense."

Using yeast bioreactors, flower scent compounds can also be introduced
to foods such as bread, or added to wine as it is prepared. Rose
flavored bread, perhaps, or a white wine with a hint of carnation. Today
food manufacturers often resort to using synthetic scent compounds in
foods, but Vainstein's work, which has been patented, will enable them
to create and use natural compounds.

Rose is already a popular flavor in many parts of the world. The
Scandinavians eat rose soup, and many other countries enjoy rose jam.
"The food industry is very interested in the potential of this," says
Vainstein. "Smell is not only what you smell with your nose, but also
what you taste. Though eating foods you also smell them. The aroma comes
from inside your mouth to your nose passage."

Vainstein is working with a number of international companies based in
the US, the UK and Israel and has carried out commercial trials. He
declines to give details, however, because of the competitive nature of
the industries he works with. "There are a number of experiments and
pilot trials going on, and we are talking to many companies about many
different possibilities but much of this work is unpublished and we are
not allowed to talk about it," he asserts, adding that contracts are
likely in the future.

Aside from scent, Vainstein's team of 14 professors and students is also
making progress in color enhancement, introducing new colors to flowers
- like gypsophila - that were traditionally white. The University has
already developed a number of strains of carnations in colors such as
cream and pale green, and work is progressing on color enhancement of
roses and gypsophila.

These transgenic flowers are being developed in only three or four
locations around the world, and the Hebrew University is the only
research lab in the world that focuses on both scent and color. "Most
labs work with only color or scent, we work with both," says Vainstein.

In future, it will be possible to create "designer flowers" to meet
specific requests - to match the color of one's clothes, eyes or
furniture, for example, or with a specific smell.

The researchers are also working on developing plants with improved
disease resistance, and plants that make more roots, creating more
flowers as a result. "There are various directions of research, but all
of them are concerned with molecular breeding," he says.

Israel is one of the biggest flower-growing nations in the world,
alongside the Netherlands, Colombia, and Kenya. The Hebrew University's
Faculty of Agricultural, Food and Environmental Quality Sciences has
played a central role in the development of flower growing in Israel
over the years. The faculty has been a partner in the development of
some 40% of the flowers now found in the market.

Vainstein's team is now exploring new avenues of research. "In Israel we
have a lot of sea water, we want to see if we can use it to grow things,
not necessarily flowers, but a lot of different things," says Vainstein.
"It's just like with scent, we start researching something just because
we are curious. If we later see applications for the knowledge we
create, then that's great."


-------------------- archived at  http://www.gene.ch/ --------------------


                                 PART II
------------------------------- GENET-news -------------------------------
TITLE:  Save the Flowers
        Would-be scent engineers aim to resurrect lost floral fragrance
SOURCE: Science News, USA
AUTHOR: Ivan Amato, Vol.168 (13): 202
URL:    http://www.sciencenews.org/articles/20050924/bob10.asp
DATE:   24.09.2005
--------------------------------------------------------------------------


Save the Flowers
Would-be scent engineers aim to resurrect lost floral fragrance

Vince Agnes, as well-appointed as the flowers that he has been selling
for more than 60 years in his shop in Silver Spring, Md., remembers when
all his roses smelled as good as they looked. When he opened for
business in the 1940s, there were only a few varieties: red, white,
yellow, and pink, he recalls. "Now, there are thousands," Agnes says, "
but only a few have a lot of scent."

No one knows what's responsible for this waning of fragrance by roses
and other ornamental-flower varieties, including carnations and
chrysanthemums, but scientists who investigate floral scent suspect that
the flower breeding that's led to an estimated 18,000 rose cultivars in
an ever-widening spectrum has run roughshod over fragrance.

"Pigment compounds are derived from the same biochemical precursors [as
scent compounds are], so it makes sense that if you make more of one you
get less of the other," notes floral-scent biochemist and geneticist
Eran Pichersky of the University of Michigan in Ann Arbor.

Floral scent may be dwindling because breeders for the $30 billion
ornamental-flower industry pay scant attention to this most emblematic
attribute of flowers. "In order of [commercial] priority, color is
number 1 through 10," says Alan Blowers, head of flower biotechnology
for Ball Helix, a biotech company in West Chicago, Ill., devoted to the
ornamental-plant industry. Beyond color, breeders have been targeting
improvements in flower longevity, shape, size, disease resistance, and
other traits likely to improve the growers' bottom lines.

Fragrance is different. It's invisible, and its sensory impression is as
subjective as taste. And, as it turns out, fragrance is a genetically
complex trait that's difficult to manipulate by ordinary breeding
methods. Despite those obstacles, Blowers predicts, "fragrance will
become important again," as the molecular biology underlying floral
scent becomes better understood.

With a nose both for understanding the molecular origins of floral
scents and for engineering what could be blockbuster flower varieties,
researchers have been teasing out the complex biochemical orchestration
underlying one of life's simplest pleasures. They've been uncovering
fragrance-related genes, the enzymes encoded by those genes, the in-cell
reactions that these enzymes catalyze, and the fragrant performance of
all this molecular biology--a vast aromatic harmony of alcohols,
aldehydes, fatty acids, terpenoids, benzenoids, and other volatile, and
therefore sniffable, chemicals.

In the past few years, flower scientists have assembled enough knowledge
and technology to consider resurrecting scents in flowers that have lost
them or engineering plants that produce scents never before experienced
by a bee, beetle, or gardener.

The researchers "have pushed the envelope in terms of our eventual
ability to change floral scent," says Michael Dobres, head of the
Philadelphia biotech company NovaFlora, which is developing genetic
methods for controlling various traits of ornamental flowers.


Deconstructing scent

The plant world perfumes, or sometimes stinks up, the environment with a
vast roster of volatile organic chemicals. Scientists have so far
identified about 1,000 of these compounds emanating from petals, leaves,
and other tissues.

"There could be up to 50, maybe 100, chemicals involved in a particular
scent," says Pichersky.

Usually, only a few of the volatile chemicals in a fragrance are
obviously noticeable to human noses. One whiff of 2-phenylethanol, for
instance, and images of roses come to mind, even though scores of
volatile chemicals contribute to the fully detailed scent of roses. Like
harmonics that help the ear distinguish a middle C played on a piano
from one played on a violin, the minor chemical components of a scent
provide the olfactory subtleties that individualize the scent of a
particular rose variety.

Pichersky, who grew up on a kibbutz growing flowers and other crops in
his native Israel and now lives on a 30-acre farm outside Ann Arbor, has
been gardening all his life. He has made it his mission to uncover as
much as he can about the biosynthesis of floral scents and the
biological roles that these scents play. In 1996, he and his colleagues
in Michigan were the first to discover a gene that produces a floral scent.

Not only do the volatiles in botanical scents attract pollinators and
delight the human nose, he notes, but they also serve to protect plants
from pathogens and pests. For example, when some plants come under
attack by munching caterpillars, they emit specific chemicals as clarion
calls for parasitic wasps. The wasps alight on the marauding
caterpillars and lay eggs, which hatch into larvae that eat the
caterpillars alive. "It's a chemical arms race out there," says Pichersky.

As the first step in analyzing the complex biochemical choreography
behind a floral scent, Pichersky and his coworkers in 1994 worked out
the amino acid sequence of the enzyme linalool synthase from petals of
Clarkia breweri, a purple wildflower native to California. They then
used that information to identify the enzyme's gene.

Through painstaking biochemical analysis, the researchers discovered
that this enzyme converts the substrate geranyl pyrophosphate into
linalool, a volatile compound with what Pichersky describes as a "wine-
sweet" smell. Geranyl pyrophosphate was already known as an intermediate
in the metabolic pathway that produces cholesterol compounds.

Since then, Pichersky's group and others have uncovered about 25 more
floral-scent genes. Natalia Dudareva, a former postdoc student of
Pichersky who now runs her own floral-scent laboratory at Purdue
University in West Lafayette, Ind., estimates that the present list of
known scent genes and their associated enzymes can account for the
cellular synthesis of no more than 5 percent of the plant volatiles that
scientists have identified.

The enzymes encoded by floral-scent genes fall into a few functional
categories with names such as synthases, methyl transferases, and
carboxymethyltransferases. Enzymes in a given category impose a
particular kind of biochemical transformation on cellular chemicals that
arise from the basic, or primary, metabolism that all plants share.

The outcome of the transformation differs according to the specific
plant. For example, in snapdragons, one particular methyltransferase
enzyme adds a methyl group (a central carbon hub bonded to three
hydrogen atoms) to benzoic acid, producing methyl benzoate. In C.
breweri, the same enzyme instead methylates salicylic acid, producing
methyl salicylate. Scientists call such species-specific biochemical
products secondary metabolites.

Mixing and matching enzymes and substrates in varying sequences of
reactions creates a bazaar of secondary metabolites, Pichersky notes.
That's how a lilac or honeysuckle, for example, can produce its own
intoxicating cocktail of fragrance compounds.

Discovery in floral-fragrance biochemistry is on a fast track, now that
lab devices can identify and analyze the activity and interactions of
hundreds to thousands of genes and proteins at once. For example,
Pichersky and a large collaboration of researchers working primarily in
Israel, a flower-exporting country, compared the genetic activity of
Fragrant Cloud, a scented rose cultivar, with that of Golden Gate, an
unscented one. From an initial roster of more than 2,000 genes that the
researchers identified as active in these two cultivars, the team
pinpointed a few genes that appeared to be involved in scent production.
This led the search to previously unrecognized enzymes, which the
researchers demonstrated were required in the biosynthesis of various
rose-scent chemicals, among them geranyl acetate and germacrene D.

Those are just a few chemical pixels in the vast picture of floral
scent. Nevertheless, Robert Raguso, a chemical ecologist at the
University of South Carolina in Columbia, characterizes the pace of
discovery in the field as explosive. "We are in this beautiful growth
phase where everything is new... and worthwhile. Now, the most
interesting challenge is putting it together," says Raguso, who was a
graduate student in Pichersky's lab in the early 1990s and whose work
led to the discovery of the linalool synthase gene.


Scent away

Even as researchers uncover more of the molecular story behind floral
scent, the goal of controlling how flowers smell remains elusive. The
genetic and biochemical complexity of fragrance continues to thwart
scientists. "Many attempts at [scent] engineering have been done, but so
far there hasn't been a lot of success," says Dudareva.

Pichersky says that scent engineering would be useful for more than just
pleasing human noses. For starters, he suggests that it will someday
empower growers to choose the pollinators that visit specific plants and
to replace some chemical pesticides with living pest controllers such as
parasitic wasps.

In one approach to manipulating plants' biochemical pathways, a team of
scientists in the Netherlands inserted into petunias the C. breweri gene
for linalool synthase that Pichersky's team had discovered. The team,
led by Harro Bouwmeester of Plant Research International in Wageningen,
the Netherlands, confirmed that the transplanted gene was working and
that the transgenic petunias were making linalool in their tissues, but
the linalool never made it out of the plant.

A related project, led by Alexander Vainstein of Hebrew University in
Rehovot, Israel, got a bit further. It produced transgenic carnations
that released linalool, but in amounts too small for a person to smell.
While Raguso says that the aroma of linalool reminds him of Earl Grey
tea, David Clark of the University of Florida in Gainesville describes
the smell as "Fruit Loopy." Clark has been approaching scent engineering
by manipulating the native genes of a single plant, a petunia, rather
than transferring scent genes from one species to another. Using current
techniques of genetic analysis and engineering, he intends to first
identify genes that might play roles in petunia scent. Then, he'll
either deactivate those genes or pump up their activity. His goal is to
make the plants produce unusually small or large amounts of the enzymes
encoded by the genes.

"We are just now figuring out where all of the pieces are in the
pathways," says Clark. He notes that petunia fragrance emerges largely
from 8 to 10 volatiles, each one created by the interplay of several
enzymes and substrates. Manipulating the plant's fragrance with finesse,
therefore, would require commandeering several genes, a dauntingly
difficult task since researchers are only sporadically successful at
achieving a desired goal when engineering even single genes.

Roman Kaiser, director of the natural-scents research unit for the
Geneva-based company Givaudan, favors studying, rather than
manipulating, floral fragrances. However, he predicts that would-be
fragrance engineers such as Pichersky, Clark, and Dudareva will
eventually have their day.

The growing body of knowledge about floral scents is likely to have a
bearing on the perfume industry as well as on flower sellers, Kaiser
says. "I could imagine that very special fragrance chemicals found in
nature, but difficult to synthesize, might be produced by applying such
techniques" in a way that improves the yield of these chemicals in the
flowers that naturally make them, he says.

If researchers do approach a time when they can engineer flowers to have
novel scents, they may discover, as have scientists in the genetically
modified food business, that winning public support for such
manipulations is the toughest challenge of all. Using genetic techniques
to alter floral scent is, in Clark's words, "a double-edged sword."

Opponents of genetically engineered food may add scent-altered flowers
to their list of products that could pose dangers. Consider a project in
which agriculturally minded genetic researchers alter fragrance genes
and the flower attracts different pollinators. "If we end up with a
plant that is covered in flies, someone will say, 'This is a freak
show,'" Clark predicts. Such a scenario could easily nip scent
engineering in the bud, he says.

Even if future scent engineers can win over public opinion, they may
have to contend with a host of low-tech factors that Silver Spring, Md.-
florist Agnes suspects have a dulling effect on floral scent. He
remembers fondly when he could buy all his flowers fresh from local
greenhouses. "Now, I get my flowers from California, from Israel,
Holland, all over the place," he says.

Flowers lose their scent while they're refrigerated during long journeys
on planes and trucks, he says. And that could be a problem, even for
high-tech flowers of the future.


References:

2004. Orchid named after Givaudan scientist. Cosmetic Business News
Center. Dec. 2. Available at http://www.cosmetic-business.com/en/
showartikel.php?art_id=113.

Dudareva, N., E. Pichersky, and J. Gershenzon. 2004. Biochemistry of
plant volatiles. Plant Physiology 135(August):1893-1902. Available at
http://www.plantphysiol.org/cgi/content/full/135/4/1893.

Kaiser, R. 2004. Vanishing flora--lost chemistry: The scents of
endangered plants around the world. Chemistry & Biodiversity 1(January):
13-27. Abstract available at http://dx.doi.org/10.1002/cbdv.200490005.

Shalit, M., A. Vainstein, E. Pichersky, et al. 2003. Volatile ester
formation in roses. Identification of an acetyl-coenzyme A. geraniol/
citronellol acetyltransferase in developing rose petals. Plant
Physiology 131(April):1868-1876. Available at http://
www.plantphysiol.org/cgi/content/full/131/4/1868.

Schwerdtfeger, M., G. Gerlach, and R. Kaiser. 2002. Anthecology in the
neotropical genus Anthurium (Araceae): A preliminary report. Selbyana
23:258-267.


Further Readings:
Vince's Agnes Flower Shop has a Web site at http://
www.vinceagnesflowershop.com.


Sources:
Alan Blowers, Ball Helix, 622 Town Road, West Chicago, IL 60185

Harro Bouwmeester, Plant Research International, P.O. Box 16, 6700 AA
Wageningen, The Netherlands

David G. Clark, University of Florida, Environmental Horticulture
Department, P.O. Box 110670, Gainesville, FL 32611-0670

Michael S. Dobres, NovaFlora, Inc., 3401 Market Street, Suite 350,
Philadelphia, PA 19104

Natalia Dudareva, Department of Horticulture and Landscape Architecture,
Purdue University, West Lafayette, IN 47907

Roman Kaiser, Givaudan Schweiz AG, Ueberlandstrasse 138, CH-8600
Dübendorf, Switzerland

Eran Pichersky, Department of Molecular, Cellular, and Developmental
Biology, University of Michigan, Ann Arbor, 1127 Natural Science, Ann
Arbor, MI 48109-1048

Robert A. Raguso, Department of Biological Sciences, 304 Coker Life
Sciences Building, University of South Carolina, Columbia, SC 29208

Alexander Vainstein, Institute of Plant Sciences and Genetics in
Agriculture, Faculty of Agricultural, Food, and Environmental Quality
Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel


-------------------- archived at  http://www.gene.ch/ --------------------


--
GENET-news

the news & information service of the
European NGO Network on Genetic Engineering

contact:
Hartmut MEYER (Mr)

phone....... +49-531-5168746
fax......... +49-531-5168747
email....... hartmut.meyer(*)genet-info.org
skype....... hartmut_meyer
url......... www.genet-info.org