Would You Like Some Rose- and Lemon-Scented Tomatoes in Your Salad?
In a BARD Fund-supported study, scientists have genetically engineered a tomato variety that exudes rose and lemon aromas. Their impressive achievement has received wide attention by the international press, as well as radio and Internet publicity.
Who has not heard the lamentation that tomatoes are not as flavorsome as they used to be? This loss is due to farmers selecting plant varieties that produce more attractive fruit with a longer shelf life at the inadvertent cost of flavor. A collaborative team of Israeli and US scientists have initiated a long term project, supported by BARD Fund, to explore the possibility of using genetic engineering tools to enhance the aroma and taste of fruits. The researchers believe that their research will help improve the quality of fruit and vegetables available at the local greens grocer.
The scientists' research method involves searching for taste and fragrance enhancing genes in aromatic flowers and spice plants, and genetically engineering these genes into the tomato plant, their model system. They have successfully isolated the genes that control the synthesis of two monoterpenes "geraniol" and "citral," from the lemon-basil plant. These two metabolites are among the most important compounds influencing the flavor of tomatoes and their products, and they possess very pleasant fragrances: Geraniol has a sweet rose scent, while citral has a lemon-like aroma. These compounds also have the added benefit of exhibiting antibacterial, anti-fungal, insecticidal, herbicidal, and anti-parasitic properties.
Advancing one-step further, the scientists have genetically engineered these genes into tomato plants. The result was a tomato variety that is both rose and lemon scented. Besides the distinct aromas, the scientists observed that these tomatoes are normal in every other respect, except for accumulating less lycopene, a natural red pigment. A subsequent survey of non-trained tasters revealed that about 95% of the panelists could easily distinguish between the regular and rose-and lemon-scented tomatoes, with 60% preferring the fragrance-enhanced variety.
The team has also been working on genetically engineering another lemon-basil enzyme, called ZIS, into the tomato fruit. Their initial results indicate that this plant's fruits accumulate significant levels of a number of savor-enhancing compounds, and that the tomato's overall aroma and taste were likewise enhanced.
The Core Group of Scientists:
- Efraim Lewinsohn, Volcani Center, Israel
- Natalia Dudareva, Purdue University, IN, USA
- Sitrit, Yaron, Ben-Gurion University of the Negev, Israel
- Eran Pichersky, University of Michigan, USA
- James Simon, Rutgers, The State University of New Jersey, USA