Characterization of resistant tomato mutants to bacterial canker disease
A small scale ethylmethanesulfonate (EMS) mutation was used to obtain resistant mutant plants to bacterial canker disease caused by Clavibacter michiganensis subsp. michiganensis isolate 2 (Cmm2). Susceptible EBR3 tomato line (200) seeds were mutagenised with the chemical EMS. Of the constructed M2 population, 450 seedlings were inoculated with Cmm2. Among the tested M2 plants, 15 M2 plants, not affected by the bacterial pathogen, produced M3 family seeds. 10 seeds from each M3 family were re-inoculated with the Cmm2, M3-9 and M3-15 family plant did not segregate for resistance confirming their resistant phenotypes. The M3-9 and M3-15 family mutant plants were analyzed for secondary metabolites especially phenolics; chlorogenic acid, caffeic acid, p-coumaric acid, rutin hydrate, ferulic acid, quercetin, naringenin and caempherol level in high performance liquid chromatography (HPLC)
system. The chlorogenic acid and rutin hydrate levels were increased in M3-9 and M3-15 family mutant plants than susceptible original EBR3 plants. The increased levels of phenolic substances could be associated with resistance phenotypes in the M3-9 and M3-15 mutants’ plants.
Keywords: Tomato, ethylmethanesulfonate mutagenesis, resistant mutants, bacterial canker