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Studying longer shelf life for tomatoes

July 19, 2010  By By Brian Wallheimer

July 19, 2010, West Lafayette, IN – A Purdue
University researcher has found a sort of fountain of youth for tomatoes
extends their shelf life by about a week.

July 19, 2010, West Lafayette, IN – A Purdue
researcher has found a sort of fountain of youth for tomatoes that
extends their shelf life by about a week.

Avtar Handa, a professor of horticulture, found
that adding a yeast gene increases production of a compound that slows aging
and delays microbial decay in tomatoes. Handa said the results, published in
the early online version of The Plant Journal, likely would transfer to most fruits.


"We can inhibit the aging of plants and
extend the shelf life of fruits by an additional week for tomatoes," Handa
said. "This is basic fundamental knowledge that can be applied to other



tomato with increased spermidine (top) stays fresh longer than those
that do
not have an increased level of the natural organic compound. (PURDUE

Handa said tomato growers and possibly other fruit
growers could use the finding soon if they wanted through either transgenic
plants or natural breeding methods.

The organic compound spermidine is a polyamine and
is found in all living cells. Polyamines' functions aren't yet fully
understood. Handa and Autar Mattoo, a research plant physiologist with the U.S.
Department of Agriculture's Agricultural Research Service and collaborator in the
research, had shown earlier that polyamines such as spermidine and spermine
enhance nutritional and processing quality of tomato fruits.

"At least a few hundred genes are influenced
by polyamines, maybe more," Mattoo said. "We see that spermidine is
important in reducing aging. It will be interesting to discover what other
roles it can have."

Savithri Nambeesan, who was a graduate student in
Handa's laboratory, introduced the yeast spermidine synthase gene, which led to
increased production of spermidine in the tomatoes. Fully ripe tomatoes from
those plants lasted about eight days longer before showing signs of shriveling
compared with non-transgenic plants. Decay and rot symptoms associated with
fungi were delayed by about three days.

"It increased the quality of the fruit,"
Handa said. "If a tomato goes to market, people won't buy it if it has
started to shrivel. If we can stop that wrinkling, we can extend the market
time of the fruit."

Mattoo said the finding could have implications
for areas that don't often get fresh fruit.

"Shelf life is a major problem for any
produce in the world, especially in countries such as in Southeast Asia and
Africa that cannot afford controlled-environment storage," Mattoo said.

"We can add this gene to the tomatoes or look
at natural variation and select the cultivars that already have a high level of
this gene's expression," Handa said.

Handa and Mattoo will continue to study polyamines
to discover how they control biological functions in fruits.

The US-Israel Binational Agricultural Research and
Development Fund, the USDA Initiative for Future Agricultural Food Systems, and
the Purdue Research Foundation funded the research.

Wallheimer is a communications specialist with Purdue University.

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