Phenotypic and molecular screening of tomato (Solanum lycopersicum L.) germplasm for root-knot nematode (Meloidogyne incognita) resistance
This study was conducted to screen some tomato (Solanum lycorpesicum L.) germplasm for root-knot nematodes (Meloidogyne incognita) resistance. Field experiment was conducted on a field heavily infested with root–knot nematodes. A pot experiment was conducted in a plant house at CSIR-Crops Research Institute. Molecular screening was also done to detect the gene that confers resistance to tomato (Mi) with specific primers (Mi23/F//Mi23/R). Six resistant cultivars - FLA 496-11-6-0, 2641A, Adwoa Deede, Tima, Terminator F1 and 2644A were identified per the molecular screening. The susceptible check (UC82) recorded the highest (2,508) J2/200 ml soil recovered from the rhizosphere of tomato which was significantly different (p=0.05) from the resistant check (VFNT) which recorded 208 J2/200ml soil in the field study. The susceptible check (UC82) also recorded a significantly (p=0.05) high (108) in J2/g root compared to the resistant check (VFNT) which recorded none. The susceptible check (UC82) and the resistant check (VFNT) recorded mean gall indices of 4.0 and 0.0 respectively on a scale of 0-5 in the field work. VFNT and three other resistant candidates - FLA 496-11-6-0, 2641A and Adwoa Deede did not gall in the pot experiment. FLA 496-11-6-0, Adwoa Deede, Tima and VFNT recorded significantly (p=0.05) high fruit yields (3.3, 5.8, 1.3 and 2.4 t/ha) respectively. The susceptible check (UC82) however, recorded low fruit yield (0.4 t/ha). Most of the susceptible cultivars recorded significant decreases in fresh and dry shoot weights with increasing inuculum density (Pi = 0, 250, 500). Six resistant cultivars identified in the molecular screening correlated well with the resistant phenotypes in the field and pot experiments.
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