COLUMBUS, Ohio — Tomato breeders who produce varieties high in lycopene are sometimes paying the price of increased nutritional benefits in the form of reduced production performance. But an Ohio State University study may have provided a solution to the dilemma.
"Incorporating tomato genes that elevate lycopene content can result in problems with slow seed germination, low-quality stands and reduced plant height," said Mark Bennett, an Ohio State University Extension and research vegetable specialist. "Some of these genes produce two to three times the normal amount of lycopene, and that can cause other biological changes in a tomato plant. High lycopene seeds will germinate, but will do so slowly and erratically."
Bennett explained it's known that with increased lycopene levels comes a decrease in compounds that enhance seed longevity (tocopherols) and seedling development (gibberellins), as well as an increase in abscisic acid (ABA), a growth hormone that inhibits germination. But what is not known is which of these has the most dominant effect on the chemical process.
The Ohio State study, lead by Bennett, geneticist David Francis, seed specialist Miller McDonald, and former graduate student Gerardo Ramirez-Rosales found that abscisic acid was the likely link between high lycopene levels and poor tomato seed quality.
By adding norflurazon, an inhibitor of ABA synthesis, and germinating seeds in the dark, the suppression of ABA levels allowed for chemical pathways, associated with seed quality, to continue. Only 50 percent of seed from a high lycopene variety germinated within four days without this treatment, while 95 percent of seed germinated with the treatment.
"We now suspect that the mechanism is strongly linked to ABA," said Bennett. "This is a good example where science was helpful in beginning to understand how the process works and what we can do to solve the problem."
Lycopene content is desirable because of the increased health benefits and to help ward off certain types of cancers, but breeders want seed that germinate quickly and plants that successfully establish themselves in the face of environmental stresses and diseases.
Bennett will present the findings of the study in a poster session at the Ohio Fruit and Vegetable Growers' Congress being held Jan. 19-21 at the Toledo Seagate Convention Centre and Radisson Hotel in Toledo, Ohio. The annual conference, which consists of general sessions, workshops, a trade show and other related events, is geared toward individuals and businesses interested in fruit and vegetable crop production and marketing.
The conference is sponsored by Ohio State University Extension, Ohio Agricultural Research and Development Center, Ohio Vegetable and Potato Growers Association and the Ohio Fruit Growers Society, Ohio Direct Agricultural Marketing Association and the Ohio Christmas Tree Association.