Resistance of Leptochloa chinensis (L.) Nees to cyhalofop-butyl and metamifop in rice fields of Zhejiang Province and involved molecular mechanism

Sprangletop (Leptochloa chinensis(L.) Nees) is one of the most serious grass weeds which can cause damage to rice field in China. To determine the resistance level of L. chinensis to aryloxyphenoxypropionates herbicides in rice fields in Zhejiang Province, a total of 11 L. chinensis populations (including one susceptible population) were collected in this study. Results of whole-plant dose-response assay tests showed that 8 populations had developed resistance to cyhalofop-butyl (resistance index: 2.1-79.1) and 9 populations had developed resistance to metamifop (resistance index: 2.0-31.0). Partial sequences of the ACCase gene in the susceptible and resistant populations were analyzed by PCR and gene clone. The Ile-1781-Val mutation was found in one resistant population and the Trp-2027-Cys mutation was found in two resistant populations. In conclusion, this study revealed that L. chinensis in rice fields in Zhejiang Province had developed different resistance levels to cyhalofop-butyl and metamifop, the Ile-1781-Val and Trp-2027-Cys mutations in the ACCase gene might contribute to the resistance in several populations.