Resistance to Candidatus Liberibacter solanacearum haplotype B in tomato landraces from Mexico

CandidatusLiberibacter solanacearum haplotype B (CLsoB) is an economically important pathogen of tomato (Solanum lycopersicumL.) crops in New Zealand and Central and North America. Currently, resistant cultivars of tomato are not available as a management tactic because breeding programmes lack sources of resistance. Therefore, the objective of this study was to identify sources of resistance in tomato toCLsoB. Forty-six landraces of tomato were collected from several states in Mexico and were inoculated withCLsoBusing 20 infested adults ofBactericera cockerelliper plant. Two assays were done over two years under greenhouse conditions. In the first trial, landraces FC22 and FC44 showed a significantly higher proportion of resistant plants, less symptom severity and longer incubation time compared with the other forty-four landraces and two susceptible cultivars. In the second assay, resistance toCLsoBof the landraces FC22 and FC44 was confirmed because they had again significantly greater numbers of resistant plants, less symptom severity, relative lowerCLsoBtiters and longer incubation time relative to the other genotypes. All plants considered resistant from both assays had DNA ofCLsoB. Results indicate that all resistant plants from these landraces are promising sources for the development of tomato cultivars with resistance toCLsoB.