Origin, Distribution, Taxonomy, Botanical description, Genetic diversity and Breeding of tomato (Solanum lycopersicum L.)

Family: Solanaceae, Sub-Family: Soloanoideae & Cestroideae, Tribe: Solaneae, Genera: Solanum, Species: Solanum lycopersicum L. Tomatoes, peppers, potatoes and eggplants all belong to the Solanaceae family of flowering plants. Plants in this family are also called nightshades. There are more than 3000 species of nightshades. Many of them are important to our economy. The Solanum lycopersicum / S. esculentum-complex contains seven species that are easily crossed with cultivated tomato and these have served as a source of genetic variability for the improvement of tomato varieties. The tomato is native to Central, South, and southern North America from Mexico to Peru. Wild tomato plants come from the Andean region of South America. This area includes the countries of Peru, Bolivia, Chile and Ecuador. The characteristics of this wild fruit were different from the cultivated fruit: small size (1-2 cm diameter), bilocular and acid taste. Tomato plants are generally much branched, spreading 60–180 cm and somewhat trailing when fruiting, but a few forms are compact and upright. Leaves are more or less hairy, strongly odorous, pinnately compound, and up to 45 cm long. The five-petaled flowers are yellow, 2 cm across, pendant, and clustered. Fruits are berries that vary in diameter from 1.5 to 7.5 cm or more. They are usually red, scarlet, or yellow, though green and purple varieties do exist, and they vary in shape from almost spherical to oval and elongate to pear-shaped. Each fruit contains at least two cells of small seeds surrounded by jellylike pulp. The tomato seed matures 35-50 days after pollination, during which seeds become germinable, desiccation tolerance is induced and water content decreases. Fruit is red and ripe by 60 days after pollination. Tomato varieties can be divided into three major categories based on their growth viz., Indeterminate, Determinate and Semi-Determinate. Tomato varieties can be divided into ten types based on shape viz., Beefsteak Tomatoes, Plum Tomatoes, Cherry Tomatoes, Grape Tomatoes, Campari Tomatoes, Tomberry Tomatoes, Oxheart Tomatoes, Pear Tomatoes, Slicing / globe Tomatoes, and Salad / Standard Tomatoes. Tomato varieties can be divided into nine types based on color viz., Red tomato varieties, Pink tomato varieties, Orange Tomato Varieties, Yellow Tomato Varieties, White Tomato Varieties, Green Tomato Varieties, Purple Tomato Varieties, Blue/black/indigo Tomato Varieties and Stripes, blushing and swirls. Wild tomato varieties were small and mostly yellow, not red. We could say that they were similar to what we know today as cherry tomatoes. Nowadays, apart from different sizes, we can also find different colors of tomatoes varying from our familiar red, to pink, yellow, orange, purple, white and black. Conventional breeding has based on standard methods which are Mass selection, Pedigree, and Hybridization. These are all conventional methods for breeding. Conventional breeding has developed the cultivars and also dominant resistance genes to control pest and disease. Tomatoes have been bred by humans for many characteristics such as yield, shelf-life, pest resistance, taste, fruit size and shape, colour, seed size and weight, and nutritional quality. By the end of the 19th century, tomatoes were bred by many farmers and gardeners. Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart among other things. Lycopene, one of nature's most powerful antioxidants, is present in tomatoes, and, especially when tomatoes are cooked, has been found beneficial in preventing prostate cancer. However, other research contradicts this claim. Tomato extract branded as Lycomato is now also being promoted for treatment of high blood pressure. In this review article Origin, Distribution, Taxonomy, Botanical Description, Genetics and Cytogenetics, Genetic Diversity, Breeding, Uses, Nutritional Value and Health Benefits of Tomato (Solanum lycopersicum L.) are discussed.