Evaluation of tomato (Solanum lycopersicum 'Pectomech') grafts against root-knot nematode Meloidogyne incognita

C. Agyeman, B.A. Okorley, J.N. Amissah, S.T. Nyaku
Grafting is a site-specific management tool that tomato growers can use to overcome soil-borne diseases without the use of chemical fumigants and/or pesticides. Root-knot nematode-resistant tomato cultivars and eggplant provide alternatives for nematode management, because susceptible cultivars can be grafted onto nematode-resistant rootstocks. In this study, four lines of three Solanum spp. (S. lycopersicum, S. macrocarpon, and S. aethiopicum) were evaluated for the presence of the Mi-1.2 gene using the Mi gene-specific primers PMIF3/R3 and C2D1/C2S4. The band sizes of 350 and 550 bp were specific to the primer pair PMIF3/R3; however, a 900 bp band size was associated with the primer pair C2D1/C2S4. Screening of the rootstocks using Mi gene-specific primers revealed that even though S. lycopersicum ‘Samrudhi F1’ and S. lycopersicum ‘Mongal F1’ possessed the Mi-1.2 gene they performed poorly in graft combinations with S. lycopersicum ‘Pectomech’ while S. macrocarpon and S. aethiopicum genotypes which lacked the Mi gene performed better in graft combinations with S. lycopersicum ‘Pectomech’. The yield of ‘Pectomech’ grafted onto the Solanum spp. and their fruit quality attributes were determined under varying Meloidogyne incognta inoculum levels – 0, 500, 1000, and 5000 (Juveniles). The varying levels of inoculum had no significant effect on the gall score index (GI≤2) and the nematode reproductive factor (RF≤1). ‘Samrudhi F1’, ‘Mongal F1’, S. aethiopicum (accession A2), and S. macrocarpon were also used as rootstocks for grafting ‘Pectomech’. The success of ‘Pectomech’/S. macrocarpon grafts and ‘Pectomech’/S. aethiopicum grafts were higher (93 and 94%) compared to those of ‘Pectomech’/S. lycopersicum ‘Mongal F1’ grafts (0%) and ‘Pectomech’/S. lycopersicum ‘Samrudhi’ grafts (0%). Even though S. macrocarpon and S. aethiopicum rootstocks are known to show tolerance to root-knot nematode infestation, this study found that they do not possess the Mi-1.2 gene, known to confer resistance to root-knot nematodes.
Agyeman, C., Okorley, B.A., Amissah, J.N. and Nyaku, S.T. (2021). Evaluation of tomato (Solanum lycopersicum 'Pectomech') grafts against root-knot nematode Meloidogyne incognita. Acta Hortic. 1302, 177-184
DOI: 10.17660/ActaHortic.2021.1302.24
grafting, eggplant, rootstock, Mi gene

Acta Horticulturae