Cross-resistance to diflufenican and picolinafen and its inheritance in oriental mustard (Sisymbrium orientale L.)

BACKGROUND An oriental mustard population (P40) was identified as resistant to diflufenican by screening at the field rate. As diflufenican and picolinafen both target phytoene desaturase (PDS), cross-resistance to picolinafen was suspected. The mechanism of resistance and its inheritance to diflufenican and picolinafen were investigated. RESULTS At the lethal dose (LD50) level, population P40 was 237-fold more resistant to diflufenican and seven-fold more resistant to picolinafen compared to two susceptible populations. Population P40 also had a significantly higher resistance to diflufenican (237-fold) than a previously described P3 population (143-fold). In addition to the Leu-498-Val mutation in PDS identified in all individuals of the P3 and P40 populations, a Glu-425-Asp mutation was also found in P40. Neither mutation was detected in any individuals of the susceptible population. As the segregation of phenotype and genotype of the F-2 individuals fitted the model for a single dominant allele, resistance to both diflufenican and picolinafen is likely encoded on the nuclear genome and is dominant. CONCLUSION Resistance to diflufenican and picolinafen in the P40 population is likely conferred by Leu-498-Val and Glu-425-Asp mutations in the PDS gene. Inheritance of resistance to these herbicides is managed by a single dominant gene. (c) 2018 Society of Chemical Industry