Database Product Description
- Host Organism
- Solanum lycopersicum (Tomato)
- Resistance to lepidopteran pests including, but not limited to, cotton bollworm, pink bollworm, tobacco budworm.
- Trait Introduction
- Agrobacterium tumefaciens-mediated plant transformation.
- Proposed Use
Production for human consumption.
- Product Developer
- Monsanto Company
Summary of Regulatory Approvals
Summary of Introduced Genetic Elements Expand
Characteristics of Solanum lycopersicum (Tomato) Expand
Donor Organism Characteristics Expand
Modification Method Expand
Characteristics of the Modification Expand
Environmental Safety Considerations Expand
Food and/or Feed Safety Considerations Expand
The tomato is a vine-like herb of the nightshade family (Solanaceae) that also includes potatoes, peppers and eggplants. Botanically this vegetable is a fruit (a berry), which although being a perennial plant in the tropics, is grown as an annual plant in northern climates. The tomato is a native of the Peru, Bolivia, and Ecuador area of the Andes Mountains. Its antiquity is uncertain in regard to cultivation but it was being cultivated when Europeans discovered America. However, it was not generally cultivated in the United States until 1835 because, until then, it was widely believed to be poisonous.
Tomatoes are propagated from seeds. In temperate regions seeds are generally started in greenhouses, hotbeds, or cold frames; the plants are set out in the fields when danger of frost is past. Fresh tomatoes are harvested by hand, while those destined for canning or for processing into soups, sauces and ketchups are harvested by machine. The numerous varieties differ greatly in plant form and fruit type, the latter ranging from a small currant size through cherry, plum, and pear forms to the large, nearly round fruits, 10 cm (4 in) or more in diameter, which are the most widely grown. All forms include red- and yellow-fruited varieties.
Tomatoes are a valuable source of food minerals and vitamins, and are low in calories. One medium-sized tomato provides 57% of the recommended daily allotment (RDA) of vitamin C, 25% RDA vitamin A, and 8% RDA iron, yet it has only 35 calories. Tomatoes are also rich in an anti-oxidant called lycopene, a carotenoid that has been found to protect cells from oxidants that have been linked to cancer. In laboratory tests, lycopene was found to be twice as powerful as beta-carotene in neutralizing free radicals. Lycopene has been linked to risk reduction for a number of types of cancers, including prostate, lung and stomach, pancreatic, cervical, colorectal, oral and esophageal cancers.
Tomatoes are subject to damage from many insects, nematodes, and fungal, viral, and bacterial pathogens. Tobacco budworm (Heliothis virescens) and tomato fruitworm (Helicoverpa zea) are destructive pests of tomato. Insect-resistant tomato line 5345 was developed using recombinant DNA techniques to express the insecticidal protein, Cry1Ac, encoded by the cry1Ac gene from the soil bacterium Bacillus thuringiensis subsp. kurstaki strain HD73. Insecticidal activity is caused by the selective binding of Cry1Ac protein to specific sites localized on the brush border midgut epithelium of susceptible lepidopteran species. Following binding, cation-specific pores are formed that disrupt midgut ion flow thereby causing gut paralysis and eventual death from bacterial sepsis. Delta-endotoxins, such as the Cry1Ac protein expressed in tomato line 5345, exhibit highly selective insecticidal activity against a narrow range of lepidopteran pests. The specificity of action is directly attributable to the presence of specific receptors in the target insects. There are no receptors for delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.
Tomato line 5345 was field tested in the United States from 1994 to 1997. Field trials were conducted to evaluate agronomic characteristics including plant height at crop maturity, yield, and maturity dates and to assess inheritance and segregation of novel traits, as well as protein toxin expression data. Comparisons with non-transformed tomato lines determined that the agronomic traits for line 5345 were well within the range of unmodified tomato lines. The only significant consistent difference between the insect resistant tomato line 5345 and the unmodified parent variety was in the expression of the insecticidal protein Cry1Ac. Field data reports demonstrated that tomato line 5345 did not exhibit weedy characteristics, and had no effect on non-target organisms or the general environment. The transformed tomato line was not expected to impact on threatened or endangered species.
Cultivated tomatoes are self-fertile, and almost exclusively self-pollinating. Their unique flower and anther morphology makes tomato an essentially cleistogamous plant, in which self-pollination and fertilization occur within an unopened flower. A low crossing rate between tomato varieties was demonstrated and attributed to the limited availability of pollen and poor foraging activity of insect pollinators.
Several related species are found as weeds in tomato fields, however, commercial tomato is generally sexually incompatible with these weedy relatives. Two Solanum species, S. lycopersicoides and S. rickii, neither of which is a weed pest in the United States, can be crossed with commercial tomato only under specific, controlled conditions requiring human intervention. The cherry tomato, L. esculentum var. cerasiforme can be crossed with tomato, L. esculentum var. esculentum. However, it would be very unlikely for tomato line 5345 to hybridize with cherry tomatoes in the United States since the rate of outcrossing in tomatoes is low and cherry tomatoes are not common in areas devoted to the large-scale cultivation of tomatoes. It was concluded that the chance of genetic exchange among tomato crops was small and outcrossing to other species, even more remote. In the event that an outcrossing event involving pollen from the transgenic tomato line 5345 did occur, it was unlikely that the insect-resistance trait would increase the plant’s weediness.
Tomatoes are consumed in both fresh (whole and sliced or diced in a variety of foods) and processed (soups, ketchup, paste, prepared sauces) forms, and the genetic modification introduced into the transgenic tomato line was not expected to result in any changes in consumption patterns.
Compositional analyses were conducted to compare transgenic line 5345 tomato fruit with fruit obtained from control non-transgenic plants grown and processed under the same conditions. The measured parameters included total solids, protein, ash, carbohydrates, calories, vitamin A, vitamin C, and folic acid. There were no statistically significant differences for any of these parameters between insect-resistant 5345 tomatoes and control tomatoes.
Tomatoes produce naturally occurring glycoalkaloids, alpha-tomatine being the most common. The level of alpha-tomatine decreases as the fruit matures so that the amounts in vine-ripened red tomatoes are negligible. The level of alpha-tomatine present in mature tomatoes from the transgenic line 5345 was within the range reported for conventional tomato varieties.
The potential for toxicity and allergenicity of the Cry1Ac protein was assessed by an examination of its physiochemical characteristics and amino acid sequence homology to known protein toxins and allergens. Unlike known protein allergens, the Cry1Ac protein was readily digested under conditions simulating the gastric and intestinal environment, and it was denatured upon heat treatment. There were no amino acid sequence homologies with known allergens or protein toxins. The Cry1Ac protein has a history of safe use, as demonstrated by its use in microbial Bt spray formulations in agriculture for more than 30 years with no evidence of adverse effects.
Links to Further Information Expand
This record was last modified on Wednesday, February 25, 2015