GMO Tomatoes May Stay Firm Longer
26 July 2016 - 1:29AM
Dow Jones News
By Daniela Hernandez
In an attempt to produce plump, tasty tomatoes with longer shelf
lives, scientists have successfully tweaked a gene that slows how
quickly the fruits soften without affecting their size or
color.
The genetically modified tomatoes, described in a paper
published Monday in the journal Nature Biotechnology, didn't show
tell-tale signs of softening, like pruned skin, 14 days after
harvesting, compared with wrinkled ones from normal plants. To
engineer them, the researchers turned to two DNA-altering
techniques, including CRISPR-Cas 9, an editing tool used to snip
out and replace unwanted genes.
The number of tomatoes growing on genetically modified and
normal plants was roughly the same. Plus, the modified plants and
normal controls had similar amounts of molecules known to affect
taste, color, and smell, according to the study.
How the new tomatoes taste is still an unsolved mystery. Because
consuming genetically modified foods isn't allowed in the U.K.,
where the research was conducted, the scientists didn't sample
their produce, said Graham Seymour, a plant biotechnologist at the
University of Nottingham and the study's lead author.
"The current work is potentially important because it only slows
down one aspect of ripening--softening--that is critical to
shipping and shelf life," said Harry Klee, a horticultural-sciences
professor at the University of Florida in Gainesville who wasn't
involved with the research.
Soft tomatoes are easily crushed, which impacts their
salability. In the U.S., the market for fresh and processed
tomatoes is about $2 billion, according to the U.S. Department of
Agriculture.
As fruits ripen, enzymes break down the component of cells that
make them tough, known as cell walls. The fruits also change color,
emit pleasing aromas and become sweeter.
That creates a chemical conundrum for fruit designers: putting
the brakes on softening also diminishes flavor. Most commercial
attempts at genetic modification haven't struck the right balance.
So for decades, academics and industrial growers have continued the
hunt for genes they could tweak to achieve both.
In the new study, which was funded in part by pesticide and seed
company Syngenta AG, the researchers homed in on a gene for pectate
lyase, an enzyme that chews up cell walls. (Syngenta declined to
comment.)
Targeting cell wall-related genes is "a promising approach" to
improve shelf life without affecting quality, said Jose Mercado, a
biotechnologist at the University of Malaga in Spain who has
studied pectate lyase's role in strawberry softening but wasn't
involved in the new study.
In 2010, he noted, scientists from India suppressed enzymes
involved in breaking down common cell-wall proteins and also grew
firmer, longer-lasting tomatoes.
It's unlikely the same DNA-wrangling technologies will be used
for tomatoes grown commercially. The tomato market isn't big enough
to "justify the cost of going through the regulatory hoops"
necessary to sell genetically modified tomatoes, said USDA plant
molecular biologist James Giovannoni. "That is why the GMOs
[genetically modified organisms] currently in the market are major
crops, like maize or soy."
The research's benefit is providing a roadmap to genes breeders
could target. It's more likely they would cross tomatoes with less
pectate-lyase activity to commercial varieties and select those
that are firm and tasty, he added.
That will require growers to figure out what conditions give
them optimal flavor and texture, at the right harvest time.
"That's something you can only do empirically," Dr. Seymour
said. The testing, he added, needs to be done by growers. His lab
will continue working on improving tomato quality. His newly
published study is part of a larger collaboration with Syngenta on
optimizing color and texture.
Write to Daniela Hernandez at daniela.hernandez@wsj.com
(END) Dow Jones Newswires
July 25, 2016 11:14 ET (15:14 GMT)
Copyright (c) 2016 Dow Jones & Company, Inc.
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