AN IN VITRO STUDY TO EXAMINE THE POTENTIAL OF MUTATION BREEDING TO CREATE RESISTANCE TO BACTERIAL WILT (RALSTONIA SOLANACEARUM) IN TOMATO

Ralstonia solanacearum which causes bacterial wilt is one of the most widespread and deadly diseases of plants worldwide. Tomato is the most susceptible crop where no effective chemical control exists and tolerant cultivars may allow for 70-80% survival. In this research five thousand tomato seeds of Lycopersicon esculentum ‘Moneymaker’ were mutated in vitro and this was followed by diplontic selection (in vitro) of the seedlings to break down chimeras. Screening for resistance to Ralstonia was then carried out on 4 week old mutant microplants through co-cultivation with the pathogen in an autotrophic system. The mutants were assessed over a 5 week period after which time 21 plants were found to have an improved/ partial resistance ranging from 10-80% over the control inoculated plants. These initial results indicate the role mutation breeding can play in creating genetic variation within tomato and also the value of an in vitro screening step in assessing the mutant population.