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NSF PR 95-82 - December 14, 1995
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No-Wilt Flowers--and No-Spoil Veggies?
Fruits that ripen on schedule, vegetables that last
longer in the refrigerator, and cut flowers that keep
their beauty and fragrance for many days may soon
be a reality, thanks to research conducted by National
Science Foundation funded scientists.
Researchers Eric Schaller and Anthony Bleecker of
the University of Wisconsin have identified the first
plant hormone receptor, responsible for a variety
of important processes in plants. Results of their
research are published in the December 15, 1995 issue
of the journal Science. The knowledge will allow biotechnologists
to fine tune developmental processes in plants that
are regulated by a plant hormone called ethylene.
Growth and development in plants and animals is controlled
by chemical signals referred to as hormones or growth
factors. The mechanisms by which these signals are
recognized, and how this information is processed
by cells, have been the subjects of massive scientific
efforts over the last few decades. Now, thanks to
modern genetic research, the first hormone response
pathway in plants is being revealed to scientists.
"The plant hormone ethylene controls such processes
as the ripening of fruits like apples, bananas, and
tomatoes," says Bleecker. "It's responsible for the
shedding of leaves by trees in autumn, and the dropping
of fruits from trees before they're ready to be picked.
It may also be responsible for the short shelf-life
of many vegetables, as well as the wilting of cut
flowers." Now the mustard weed Arabidopsis thaliana,
commonly used in plant genetic research, is providing
researchers like Schaller and Bleecker with information
on the genes involved in cellular responses to ethylene.
The hunt for the genes began more than eight years
ago, with the identification of mutant forms of Arabidopsis
that lacked the ability to respond to ethylene. Schaller
and Bleecker's research on a gene called ETR1 has
now proved that this gene "codes for" the ethylene
receptor in Arabidopsis. But what about other plants?
Does a similar mechanism work in roses or tomatoes?
The answer, for tomatoes at least, also appears in
this issue of Science. Botanist Harry Klee of the
University of Florida studies a mutant form of tomato
called "never-ripe" that has showed a dramatic delay
in fruit ripening. Klee recently used the ETR1 gene
sequences from Arabidopsis to discover similar genes
in tomato plants. The DNA sequence of the "never-ripe"
gene from these tomatoes is strikingly similar to
that of the Arabidopsis ETR1 gene, says Bleecker.
This new understanding of how ethylene works will
allow botanists to regulate developmental processes
in many plants, Schaller and Bleecker believe. For
example, mutant forms of ETR1 and "never-ripe" are
what geneticists call dominant. When mutant forms
of the gene are transferred into plants with normal
genes, the mutant form overrides the normal form,
resulting in a reduction or elimination of ethylene
responsiveness. This process may soon be used to keep
cut flowers fresh longer -- and extend the life of
those veggies currently moldering away in your refrigerator
bin. -end-
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