Identification of resistant genes linked to Fusarium wilt disease in tomato (Lycopersicon esculentum) cultivars using CAPS markers

Fusarium wilt causes cosiderable yield loss in most tomato-growing regions around the world. The best way to control this disease is using tomato resistant cultivars. Molecular markers linked to resistance gene would be useful for tomato improvement programs. In this study, a cleaved amplified polymorphic sequence (CAPS) marker (TAO1902) was used to identify tomato cultivars possessing I-2 gene, which confers resistance to Fusarium oxysporum f. sp. lycopersici race 2. DNA was extracted using CTAB method from 27 hybrids and commercial tomato varieties. To evaluate existence of I-2 gene in tomato cultivars, PCR-RFLP was down using RsaI and FokI restriction enzymes. An RsaI-digested fragment of 500 bp and two restriction fragments of 390 and 410 bp for FokI digestion of TAO1902 were revealed in the resistant varieties. Results showed that 14 out of 27 tomato hybrids and cultivars were homozygous resistant and the other 13 hybrids were susceptible to fusarium wilt. Pathogenicity test showed that there were no symptoms in resistance gene I-2 amplifing tomato varieties. However, tomato varieties with no resistance band produced disease symptoms with different disease intensities. Results showed that 7 out of 27 tomato cultivars and hybrids, and 7 hybrids were resistant to F. oxysporum f. sp. lycopersici race 2 and so, these cultivars and hybrids are recommended in regions that race 2 of the fungus is dominant.