Abstract: To determine the acetyl-CoA carboxylase (ACCase) inhibitors resistance and diversity of the target ACCase gene mutations in Digitaria spp., we assessed the metamifop, cyhalofop-butyl, and fenoxaprop-P-ethyl resistance of 59 populations collected from rice fields in Jiangsu Province that were highly infested by Digitaria spp. by the discriminating dose assays, and analyzed the ACCase gene mutations. The results showed that there were 2, 8, and 3 Digitaria spp. populations marked as highly resistant, resistant, and developing resistant populations at the discriminating dose (90 g·hm^-2) of metamifop, respectively. There were 8, 14, and 8 populations identified as highly resistant, resistant, and developing resistant populations at the discriminating dose (105 g·hm^-2) of cyhalofop-butyl, respectively. There were 2, 7, and 8 populations confirmed as highly resistant, resistant, and deve-loping resistant populations at the discriminating dose (20.7 g·hm^-2) of fenoxaprop-P-ethyl, respectively. Target ACCase gene sequencing in 30 resistant Digitaria spp. populations revealed that there were three ACCase resistance mutations in 18 populations, including Trp (TGG)-2027-Cys (TGC/TGT), Trp (TGG)-2027-Ser (TCG), and Ile (ATT)-2041-Asn (AAT). In conclusion, the resistance of Digitaria spp. in northern region of Jiangsu Province to ACCase inhibitors herbicides was relatively severe, with ACCase gene mutations as the main cause of its resistance.

Key words: Digitaria spp., acetyl-CoA carboxylase, resistance detection, gene mutation, rice field