The cultivated tomato has a narrow genetic diversity that resulted from its intense selection and inbreeding during evolution and domestication thus, these species are more prone to disease epidemics. However, the commercial production of tomato has been hindered by many fungal, bacterial, viral and nematode diseases including early blight. Higher production of tomato is therefore required to fulfill the ever-increasing demand. Because of its wide use and nutritional values, there is a high demand for both fresh market and processed tomato varieties. Tomato is the richest source of vitamin A and C and supplies a sufficient amount of the antioxidant lycopene pigment that helps to protect the body against cancer and heart disease. Tomatoes are consumed in several ways: fresh, mixed in other food items or processed and canned as sauce, ketchup, juice, salsa, paste, soup and pickled. The USA ranks in third position in the total world production of tomato after China and India. USA tomato production contributes 13.2 million metric tons with a value of $5 billion to the total world production. The total world production of tomato is 161.7 million metric tons with a value of ∼$59 billion. Tomato is the world’s second most consumed vegetable after potato. It can be grown in a wide range of climates from tropical to temperate it also can be cultivated under cover conditions when outdoor temperatures are not favorable. Tomato ( Solanum lycopersicum Linnaeus), native to the Andean region of South America, is one of the most common horticultural crops and cultivated throughout the world. This paper will review the current understanding of causal agents of EB of tomato, resistance genetics and breeding, problems associated with breeding and future prospects. More research is needed to identify additional sources of useful resistance, to incorporate resistant QTLs into breeding lines through marker-assisted selection (MAS) and to develop resistant cultivars with desirable horticultural traits including high yielding potential and early maturity. Pyramiding of those QTLs would provide strong resistance. pimpinellifolium, but none of them could be used in EB resistance breeding due to low individual QTL effects. Several quantitative trait loci (QTL) conferring EB resistance have been detected in the populations derived from different wild species including Solanum habrochaites, Solanum arcanum and S. Polygenic inheritance of EB resistance, insufficient resistance in cultivated species and the association of EB resistance with undesirable horticultural traits have thwarted the effective breeding of EB resistance in tomato. Resistance sources have been identified in wild species of tomato some breeding lines and cultivars with moderate resistance have been developed through conventional breeding methods. Currently, cultural practices and fungicide applications are employed for the management of EB due to the lack of strong resistant cultivars. Alternaria are known only to reproduce asexually, but a highly-virulent isolate has the potential to overcome existing resistance genes. In some instances, annual economic yield losses due to EB have been estimated at 79%. Early blight (EB) is one of the dreadful diseases of tomato caused by several species of Alternaria including Alternaria linariae (which includes A.
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