Investigating the mechanisms of flucarbazone-sodium resistance in Bromus japonicus Thunb

Bromus japonicus Thunb. is a hazardous weed in wheat fields in China. One B. japonicus population, HB-1, which was collected in Hebei Province, survived field rate flucarbazone-sodium exposure.

To investigate the mechanism of flucarbazone-sodium resistance in the HB-1 population, the herbicide target als gene was isolated, and the in vitro ALS activity was tested. HPLC‒MS/MS was applied to detect flucarbazone-sodium absorption and residue level. Furthermore, RNA-seq and qRT‒PCR were applied to detect genes related to flucarbazone-sodium metabolism or flucarbazone-sodium and its metabolite transport.

The results indicated that in resistant population there were no mutations in the als gene sequences or differences in the IC₅₀ of ALS compared with the sensitive population. In addition, als gene relative copy number and expression also showed no difference. However, significantly increased herbicide metabolism was found in the HB-1 population. In the end, four cytochrome P450 genes (C71D55b, C71A1, C71D55, T5H), three glutathione S-transferase genes (GSTZ, GSTU6b, GSTFB), and three ABC transporter genes (ABCC3, ABCF1, ABCG11) were selected and identified as potentially playing a role in flucarbazone-sodium resistance.