摘要
Flixweed（Descurainia sophia L.） is a problematic and widespread weed in winter wheat fields and has been controlled by tribenuron-methyl for more than twenty years in China. In this study, a flixweed accession（Hebei 25, HB25） with an Asp-376-Glu mutation in acetohydroxy acid synthase（AHAS） was identified and purified. The purified HB25 accession（p HB25） developed 758.1-fold resistance to tribenuron-methyl and exhibited obvious cross-resistance to four AHAS-inhibiting herbicides. The resistant/susceptible（R/S） ratios of 50% plant growth reduction（GR_（50）） to herbicides of halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 346.1, 15.7, 8.1 and 7.1, respectively. The reduced AHAS sensitivities to four different AHAS-inhibiting herbicides, which were caused by the Asp-376-Glu mutation, were responsible for the resistance and cross-resistance to AHAS-inhibiting herbicides. The R/S ratios of 50% inhibition of AHAS activity（I50） to tribenuron-methyl, halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 844.5, 532.9, 74.5, 13.3 and 5.5, respectively. The results of AHAS activity in vitro were highly correlated with that of whole-plant response experiments.
Flixweed（Descurainia sophia L.） is a problematic and widespread weed in winter wheat fields and has been controlled by tribenuron-methyl for more than twenty years in China. In this study, a flixweed accession（Hebei 25, HB25） with an Asp-376-Glu mutation in acetohydroxy acid synthase（AHAS） was identified and purified. The purified HB25 accession（p HB25） developed 758.1-fold resistance to tribenuron-methyl and exhibited obvious cross-resistance to four AHAS-inhibiting herbicides. The resistant/susceptible（R/S） ratios of 50% plant growth reduction（GR_（50）） to herbicides of halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 346.1, 15.7, 8.1 and 7.1, respectively. The reduced AHAS sensitivities to four different AHAS-inhibiting herbicides, which were caused by the Asp-376-Glu mutation, were responsible for the resistance and cross-resistance to AHAS-inhibiting herbicides. The R/S ratios of 50% inhibition of AHAS activity（I50） to tribenuron-methyl, halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 844.5, 532.9, 74.5, 13.3 and 5.5, respectively. The results of AHAS activity in vitro were highly correlated with that of whole-plant response experiments.
基金
sponsored by the Special Fund for Agro-scientific Research in the Public Interest,China(201303031)
