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ARS Research May Lead to Tastier TomatoesBy Luis Pons
April 11, 2002
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 tomatoes.
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.