Current Status of Early Blight Resistance in Tomato: An Update

• Published in: International journal of molecular sciences 2017-09, Vol.18 (10), p.2019
• Main Authors: Adhikari, Pragya, Oh, Yeonyee, Panthee, Dilip R
• Format: Article
• Language: English
• Subjects: Alternaria; Alternaria - pathogenicity; Alternaria - physiology; Breeding; Chromosome Mapping; Chromosomes, Plant - chemistry; Cultivars; Disease Resistance - genetics; Early blight; Fungicides; Genetic Linkage; Genetic Markers; Genotype; Genotype & phenotype; Horticulture; Marker-assisted selection; Plant Breeding - methods; Plant diseases; Plant Diseases - genetics; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Immunity - genetics; Polygenic inheritance; Quantitative Trait Loci; Review; Solanum lycopersicum - genetics; Solanum lycopersicum - immunology; Solanum lycopersicum - microbiology; Tomatoes
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms18102019

Early blight (EB) is one of the dreadful diseases of tomato caused by several species of including (which includes and ), as well as In some instances, annual economic yield losses due to EB have been estimated at 79%. are known only to reproduce asexually, but a highly-virulent isolate has the potential to overcome existing resistance genes. Currently, cultural practices and fungicide applications are employed for the management of EB due to the lack of strong resistant cultivars. 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. 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. Several quantitative trait loci (QTL) conferring EB resistance have been detected in the populations derived from different wild species including , and , but none of them could be used in EB resistance breeding due to low individual QTL effects. Pyramiding of those QTLs would provide strong resistance. 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. 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.