May Lead to Tastier Tomatoes
By Luis Pons
April 11, 2002
New Agricultural Research Service (ARS)-led discoveries about a gene that
makes tomatoes ripen may lead to tastier tomatoes, according to an article in
the current issue of Science
ARS researchers in Ithaca, N.Y., along with scientists from the
Boyce Thompson Institute for Plant
Research at Cornell University,
Texas A&M University, and Jealott's Hill
Research Station in the United Kingdom, have developed new scientific
information about the ripening-inhibitor (RIN) gene that controls ripening in
Previously, researchers knew that ethylene, a gas naturally produced by
plants, stimulates ripening in many fruits, including the tomato. According to
ARS molecular biologist Jim Giovannoni, an additional genetic trait in
tomatoes--and probably other fruits--also affects ripening and various quality
characteristics. Work by Giovannoni and his team reveals that the RIN gene is a
regulatory gene, a special kind of gene that controls the activity of other
genes. The RIN gene affects both ethylene production during ripening and other
processes of ripening that are not dependent upon ethylene.
The discovery may be the breakthrough that leads to a better-tasting tomato
that meets commercial shelf-life needs. Currently tomatoes are picked and
shipped while green and unripe. They are then gassed with ethylene to make them
ripen, but this process does not always recreate all the characteristics of a
good vine-ripened tomato. What is needed is a substitute for green picking that
will help maintain both a long shelf life and the ability to ripen properly.
The RIN gene and a nonfunctioning mutant form of the gene both occur
naturally in tomatoes. The natural variant form, which blocks ripening, gives
greater fruit firmness and shelf life and may be useful as an alternative to
picking while green. Fine-tuning of RIN gene activity between the mutant and
normal forms could make it possible to increase shelf life while maintaining
the desirable characteristics of a vine-ripened tomato.
The new discovery may allow scientists to enhance specific desirable aspects
of ripening, including flavor, color intensity and perhaps even vitamin and
mineral contents, making fruit even more nutritious. The gene and its natural
variant could also be useful to increase shelf life in other fruits where
mutant forms of the RIN gene are not available.
The RIN gene was found to be a member of the so-called MADS-box gene family
whose members control floral development in plants. Interestingly, the ARS-led
research was the first to prove that ripening is directly controlled by a gene
associated with the floral development process.
ARS is the U.S. Department of
Agricultures chief scientific research agency.