New Zealand
February 1, 2008
International attention is
focusing on “tearless onion” research being conducted by senior
Crop & Food Research
scientist Dr Colin Eady.
Dr Eady and his collaborators in Japan have been testing
tearless onions in the laboratory and have presented their
results so far to the 5th International Symposium on Edible
Alliaceae, in The Netherlands.
Dr Eady describes “tearless” onions as being in the
developmental stages but if the research progresses well, would
like to see them become the household and industry norm within
the next decade.
“We have been using a gene-silencing technology, called RNAi,
developed by Dr Peter Waterhouse at CSIRO in Australia, that
allows us to retarget the plant’s own natural regulation system
without expressing foreign proteins in the plant,” Dr Eady says.
“Through RNAi, genes can be specifically shut down or turned
off. By shutting down the lachrymatory factor synthase gene, we
have stopped valuable sulphur compounds being converted to the
tearing agent, and instead made them available for redirection
into compounds, some of which are known for their flavour and
health properties.”
Dr Eady says the research team has been unable to induce tearing
by crushing their model tearless onions.
“What we have now is a truly unique germplasm with a unique
trait. We can home in and study what the consequences of this
one effect are. We can detect differences in sulphur compounds
known to be involved in flavour and health and actually measure
them and assign to them a role.”
International onion trade journal
Onion World is featuring
Dr Eady’s work on the front cover of its final issue for 2007.
The magazine quotes Dr Michael J. Havey, Professor of
horticulture at the University of Wisconsin and USDA research
geneticist, as well as world-renowned onion scientist, as
predicting that tearless onions will become a mainstay in
household kitchens around the world. He said Dr Eady’s work was
“clearly the No. 1 topic of discussion at the 5th International
Symposium”.
Dr Eady says although the “tearless onion” is an exciting
project, he is most interested in sustainable and efficient
production and will want to be sure that the onions he is
working on are also capable of being grown in an efficient
manner. “We have a burgeoning population to feed, and with
climate change and other challenges, available resources are
being reduced. The gene silencing system can also be used to
combat virus diseases and biotechnology in general can help us
produce more robust crops.”
Dr Eady says in many countries onions already contribute a
significant proportion of the daily fibre requirements of the
populations. “They are such a versatile and nutritious
vegetable, that if we can manage to get more people cooking and
eating fresh onions, then that has got to be a positive
outcome.” |
|
Onion Fact box |
|
The ancient Egyptians, and many
civilisations since, valued
onions not only as a food but as
a medicine. Modern medical
science has confirmed these
beliefs, showing that the
fructan, flavonoid and sulfur
compounds combine to make onion
a truly functional (healthy)
food. Fructans for instance,
enhance the value of the onion
by conferring prebiotic
properties and lowering blood
lipid and insulin levels.
Onion is one of the most
valuable vegetable crops in the
world.
The onion has an extremely large
genome size, 36 times that of
rice, which complicates
application of key molecular
technologies when studying this
vegetable.
|
|
