I Say Tomayto, You Say Tomahto...4

Table 3. Some Popular Early Cultivars in the United States [3]
 

Cultivar name	List Dates
Ferry's Improved  Tilden's  General Grant  Red Pear  Trophy  Canada Victor  Acme  Essex Early Hybrid  Turk's Turban  Favorite  Golden Queen  Early Michigan  Mikado  Buckeye State  Matchless  Earliana  Globe  Bonny Best  Avon Early  Cooper's Special	1868-1888 1868-1878 1871-1883 1872-1936 1872-1926 1874-1892 1879-1930 1881-1912 1880-1882 1883-1907 1886-1936 1889-1930 1889-1902 1895-1915 1901-1922 1904-1936 1906-1936 1916-1936 1921-1936 1926-1936

As with any homozygous crop, hybrid breeding can result in terrific gains in production and quality. When two homozygous lines are crossed, the resulting progeny inherit a high degree of genetic variability which leads to heterosis, or hybrid vigor, and perform much better and/or produce much more than either one of the parents. In this case, 1+1=3. One of the first hybrid tomatoes, Mikado, was introduced in 1880 by Rice's Seed Company of New York (Fig 11) [5]. Like most early hybrids, the Mikado's claim to fame was increased fruit size. Soon, higher yields were incorporated. By the beginning of the twentieth century, disease resistance, bush type and determinate growth habits were also found in hybrid cultivars. These traits were mostly incorporated into cultivated tomato by crossing with a wild relative, since all will hybridize with varying amounts of success [6]. Hybrid cultivars have come to dominate every area of tomato production, from large scale to backyard. One drawback, as far as the home gardener is concerned, is that hybrid seed or plants must be purchased every year. Seed from hybrid plants, if propagated, will produce the F2 segregating generation, and plants will be very diverse and not at all like that parent. This is the very property that makes hybrids so attractive to seed producers since it ensures that customers must buy new seed each year. Heirloom cultivars grow true from seed, and are still propagated by many home gardeners and seed companies. Many people argue that new hybrid cultivars bred for size and yield have overlooked the taste, and that the flavor of heirloom cultivars can't be beat. Hybrid cultivars have historically looked and tasted very similar to each other. Heirlooms definitely present greater variety, but typically have lower yields and lower disease resistance.
 
Tomato production in western countries began to soar in the early 1920's with the advent of mass canning. Canning of tomatoes was first documented in 1847 by Harrison Crosby of Lafayette College in Easton, Pennsylvania [3]. Prior to 1890, all tomato canning was done by hand. Mechanized peeling tables were put into use in the 1890's. Juice extractors were invented in the 1920's. Shortly after, a young entrepreneur named Joseph Campbell found a ready market for canned tomato products, and went on to make millions with his soup company.  High-solids cultivars have been introduced to maximize paste and solids for canning. Roma is a backyard favorite spanning half a century of cultivation and has been widely used for sauces because of its high solids content.
 
As the potential for introducing new traits into tomato cultivars through hybridization with wild relatives became more lucrative, the Tomato Genetics Cooperative was established at Cornell University in 1951 to collect and disseminate useful germplasm for breeding projects [3]. A prominent tomato breeder named Charles Rick heads up the Tomato Genetic Resource Center at University of California at Davis. In addition, tomato germplasm is kept in storage at the USDA National Seed Storage Laboratory in Fort Collins, Colorado. 
 
The late sixties sci-fi flick Attack of the Killer Tomatoes scared no one, but entertained millions. Tomatoes have been subject to politicking as well. In 1981, the USDA chairman declared ketchup to be a vegetable in order to justify Reagan administration budget cuts in the school lunch program [1].
 
The most recent contribution to tomato breeding has been biotechnology. For years merchants have tried to balance a good tasting fruit with a tough, good-shipping fruit. Ripe tomatoes are very soft, bruise easy, and begin to decline in quality after only a few days. Tomatoes ripen off the vine in response to the chemical ethylene, which is produced by the fruit as the development of the seeds nears completion. Traditionally, growers pick the fruits in the green-mature stage just as the shoulders of the fruit lose their dark green color. The fruit is then shipped to other locations, sometimes thousands of miles, and resists bruising or rotting because of its immature stage. The fruits are usually red by the time they reach their destination, or they can be induced to ripen with the application of an ethylene spray. Consumers often complain that taste suffers because of this practice.  In the 1980's a project was undertaken by Calgene Fresh, Inc. using biotechnology to tweak the tomato genetics to inactivate the gene responsible for softening the tomato during ripeness. These tomatoes turned red, but remained firm indefinitely. The practice of picking tomatoes green could be discarded, and everyone would be happy. They called this cultivar Flavr Savr because vine-ripening supposedly gave it better flavor. It hit the produce sections of stores in the US during 1993 [1]. The Flavr Savr tomato represents one of the greatest public relations blunders of the decade. Industry executives severely underestimated the public's concern over biotechnology, and failed to anticipate the backlash from consumers over this new and potentially risky technology applied to human food. Although evidence suggesting any danger over genetically engineered food is lacking, consumers are nervous about potentially unknown and unforeseen side effects. The Flavr Savr tomato was soon removed from supermarket shelves, and has never been reintroduced. 
 
The latest buzz surrounding tomatoes is the purported benefit of lycopene, the major carotenoid contained in tomatoes that is responsible for the deep red color. Similar to beta-carotene, lycopene has been touted as a potent anti-oxidant, a molecule which snuffs out cancer-causing free radicals within mammalian systems [15]. Tomatoes are an excellent source of lycopene, and numerous studies have confirmed that people who consume increased amounts of tomato products experience marked reductions in cancer risk [16]. Results from cancer research has already driven tomato breeders at the University of Florida to produce high lycopene cultivars. L. esculentum's wild relative, L. pimpinellifolium, also known as the currant tomato, produces tiny fruits which contain over 40 times more lycopene than domesticated tomatoes (Fig 12). Since hybrids between the two are relatively simple to achieve, this source of genetic diversity is open for exploitation, and will most likely become a sought-after hybrid trait. 
 
The top five tomato producing countries of the world are United States, China, Turkey, Italy and India, in that order. Within the US, Florida, California and Georgia are the top commercial producing states, with about 200 square miles under cultivation in 1997. An estimated 35 million backyard gardens across the country grow tomatoes as well. Per capita yearly consumption of tomatoes in the US increased from 16.6 lb in 1985 to 18.8 lb in 1995 [11]. Continued increase in this figure is expected due to the purported health benefits associated with tomatoes in the diet.  Specifically, these include a ranking of 16th among all fruits and vegetables as a source of vitamin A, 13th in vitamin C, and when adjusted for consumption, the most important provider of these two vitamins in the western diet. It also contains significant amounts of lycopene, beta-carotene, magnesium, niacin, iron, phosphorus, potassium, riboflavin, sodium and thiamine. A University of California at Davis survey ranked the tomato as the single most important fruit or vegetable of western diets in terms of overall source of vitamins and minerals. 
 
After only a few hundred years in European culture, the tomato has firmly implanted itself as a major player in diets of many nationalities. Italian cooking has become synonymous with tomato sauce. Pizza would be lost without it. Where would Mexican restaurants be without salsa? Tomato soup, slices on a burger and ketchup are all highly integrated uses for the versatile fruit in American culture. Additionally, millions of Americans grow tomatoes in their backyards each year. From one continent to another, the tomato has crossed through a variety of cultural barriers to become one of the world's foremost vegetables.