College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China; Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Pestic Biochem Physiol. 2024 Sep;204:106099. doi: 10.1016/j.pestbp.2024.106099. Epub 2024 Aug 24.
Echinochloa crus-galli (L.) P. Beauv is a monocotyledonous weed that seriously infests rice fields. Florpyrauxifen-benzyl, a novel synthetic auxin herbicide commercialized in China in 2018, is an herbicide for controlling E. crus-galli. However, a suspected resistant population (R) collected in 2012 showed resistance to the previously unused florpyrauxifen-benzyl. Whole-plant dose-response bioassay indicated that the R population evolved high resistance to quinclorac and florpyrauxifen-benzyl. Pretreatment with P450 inhibitors did not influence the GR of E. crus-galli to florpyrauxifen-benzyl. The expression of target receptor EcAFB4 was down-regulated in the R population, leading to the reduced response to florpyrauxifen-benzyl (suppresses over-production of ethylene and ABA). We verified this resistance mechanism in the knockout OsAFB4 in Oryza sativa L. The Osafb4 mutants exhibited high resistance to florpyrauxifen-benzyl and moderate resistance to quinclorac. Furthermore, DNA methylation in the EcAFB4 promoter regulated its low expression in the R population after florpyrauxifen-benzyl treatment. In summary, the low expression of the auxin receptor EcAFB4 confers target resistance to the synthetic auxin herbicide florpyrauxifen-benzyl in the R- E. crus-galli.
稗草是一种单子叶恶性杂草，严重侵害稻田。氟吡草腙是一种于 2018 年在中国商业化的新型合成生长素除草剂，用于防治稗草。然而，2012 年采集到的一个疑似抗性种群（R）对之前未使用过的氟吡草腙表现出抗性。全株剂量反应生物测定表明，R 种群对氯喹草和氟吡草腙产生了高度抗性。用 P450 抑制剂预处理并不影响稗草对氟吡草腙的 GR。靶受体 EcAFB4 在 R 种群中的表达下调，导致对氟吡草腙的反应减弱（抑制乙烯和 ABA 的过度产生）。我们在水稻 Oryza sativa L. 的 OsAFB4 敲除体中验证了这种抗性机制。Osafb4 突变体对氟吡草腙表现出高抗性，对氯喹草表现出中等抗性。此外，EcAFB4 启动子中的 DNA 甲基化在氟吡草腙处理后调节其在 R 种群中的低表达。总之，生长素受体 EcAFB4 的低表达赋予稗草 R 对合成生长素除草剂氟吡草腙的靶标抗性。
