Field Reactions of Segregating Populations of Interspecific Hybrids of Lycopersicon Species to Natural Infection by Xanthomonas campestris pv. vesicatoria (Doidge) Dye

Abstract

The progenies arising from crosses between cultivated tomatoes and a wild relative were screened with their parents for resistance to bacterial leaf spot disease. The aim is to develop a tolerant variety that is well adapted to humid forest ecology where the disease is endemic. The results obtained showed that the cultivated varieties, Roma and Nsukka local, were highly susceptible with disease incidence of 100 per cent. The wild relative on the other hand showed a high level of resistance with a reduced disease incidence. The reactions of the backcrosses and F2 offspring were not impressive as negligible percentage of resistant plants were identified in the F2 . Plants with resistance were recovered in the F3 generation from crosses between the wild and L. esculentum indicating the possibility of transfer of gene(s) for resistance of leaf spot from the wild to the cultivated tomatoes. The increase in the number of resistant plants in this generation is an indication that genes for resistance to leaf spot can be accumulated over generations thereby increasing the selection potentials for resistance to the pathogen in higher generations.