Target-site basis for resistance to imazethapyr in redroot amaranth (Amaranthus retroflexus L.)

Zhaofeng Huang, Jinyi Chen, Chaoxian Zhang*, Hongjuan Huang, ShouhuiWei, Xinxin Zhou, Jingchao Chen, XuWang

Abstract：Experiments were conducted to confirm imazethapyr resistance in redroot amaranth (Amaranthus retroflexus L.) and study the target-site based mechanism for the resistance. Whole-plant response experiments revealed that the resistant ? population exhibited 19.16 fold resistance to imazethapyr compared with the susceptible (S) population. In vitro ALS activity assay demonstrated that the imazethapyr I50 value of the R population was 21.33 times greater than that of the S population. However, qRT-PCR analysis revealed that there is no difference in ALS gene expression between the R and S populations. Sequence analysis revealed an Asp-376-Glu substitution in ALS in the R population. In order to verify that the imazethapyr resistance was conferred by Asp-376-Glu mutation, the ALS-R and ALS-S genes were fused to the CaMV 35S promoter and introduced into Arabidopsis respectively. The expression of ALS-R in transgenic Arabidopsis plants exhibited 13.79 fold resistance to imazethapyr compared to ALS-S transgenic Arabidopsis.

Key Words：Acetolactate synthase (ALS)Herbicide resistanceImazethapyr Arabidopsis

Pesticide Biochemistry and Physiology，2016, 128()：10-15

https://doi.org/10.1016/j.pestbp.2015.10.011