For Real: A Store-Bought Tomato with Vine-Ripened Taste

By Doris Stanley Lowe
May 12, 1999

Changing the levels of a key hormone in tomatoes could lead to fruit that tastes better and lasts longer, Agricultural Research Service scientists report. Research shows such a tomato to be only a few years away.

ARS plant physiologist Jerry D. Cohen and colleagues have genetically altered the levels of auxin, a hormone which causes a tomato to grow and ripen. It’s the best known—and probably the most important—of the five major plant hormones.

Scientists have been studying auxin for more than 120 years. They’ve been able to change auxin levels, but the changes were expressed throughout the plant, not just in the fruit. The aim is to control the hormone production so that it can be introduced into specific, targeted tissues--such as the fruit-- without affecting the growth processes in other parts of the plant.

At the ARS Horticultural Crops Quality Laboratory in Beltsville, Md., Cohen and colleagues inserted a backwards copy of iaglu—a gene from corn—into a tomato to turn this gene off. Because the gene was put in with a fruit-specific promoter, only the tomato fruit was affected. The resultant fruit ripened more slowly. This work is in collaboration with scientists in the ARS Climate Stress Laboratory in Beltsville. ARS is the chief scientific agency in the U.S. Department of Agriculture.

Another plus for auxin: Decreasing the gene’s level of expression throughout receptor plants caused them to easily form large numbers of roots from cuttings and spurred rapid root growth in germinating seedlings. This could be significant for plants that are difficult to root from cuttings and could increase the survival rate of seeds planted in dry soils.

Cohen expects this research to produce a store-bought tomato with vine-ripened taste in about 3 years.

Scientific contact: Jerry D. Cohen, ARS Horticultural Crops Quality Laboratory, Beltsville, Md., phone (703) 306-1442, fax (703) 306-0355, jdcohen@NSF.gov (on detail to the National Science Foundation until October 1999).