[Induction and genetic analysis of laboratory mutants of Gibberella zeae resistance to carbendazim].

The mutants of wild-type Gibberella zeae resistance to carbendazim were generated in laboratory by ultra-violet (UV) irradiating and fungicide taming. Two levels of resistance (low, LR; high, HR) were identified among these mutants. LR mutants could grow at the critical concentration of 1.4 +/- microg/mL of carbendazim while completely inhibited above 10 microg/ mL concentration, but this phenotype of isolates was not detected in the field. HR mutants could grow at 100 microg/mL and showed negative cross-resistance with N-phenylcarbamate fungicides, such as N-( 3,5-dichlorophenyl) carbamate (MDPC) whereas the LR mutants were not. Moderate resistant (MR) mutants which could grow fast at 10 microg/mL, but completely inhibited at 100 microg/mL, were not generated in laboratory. HR mutants of field MR isolate were also generated by fungicide taming on 100 microg/mL of carbendazim, but these mutants did not express negative cross-resistance to MDPC. The genetic study suggested that the carbendazim-resistance in these mutants could be steadily inherited by asexual and selfed reproduction, and the resistance was controlled by the same single major gene both in laboratory mutants and field resistant isolates, the different levels of resistance or the same resistant level in different strains maybe conferred by mutations at different sites or one site with different allelic mutations. The gene compensates for the sensitivity to MDPC was allelic to that governs the carbendazim resistance, but the mutation for increasing sensitivity to MDPC in this gene could get the pathogen highly resistant to carbendazim.