Qian Hongjia, Shi Huazhong
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79424, USA.
J Exp Bot. 2024 Dec 4;75(22):7096-7106. doi: 10.1093/jxb/erae330.
Herbicides play a crucial role in boosting crop yields, yet the emergence of herbicide-resistant weeds and the susceptibility of crops to herbicides have posed significant challenges to their efficacy. β-Triketone herbicides specifically target the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), which is essential for plant growth. Remarkably, few resistant weeds have been identified against these herbicides. In this study, we aimed to identify mutations within the cotton HPPD gene that confer resistance to mesotrione, a widely used triketone herbicide. Through the establishment of a high-throughput mutant screening system in Escherichia coli, we identified four single nucleotide changes leading to amino acid substitutions in HPPD, resulting in mesotrione resistance while preserving native enzymatic activity. Various combinations of these mutations displayed synergistic effects on herbicide resistance. Additionally, the HPPD variants were able to complement the Arabidopsis athppd mutant, indicating their retention of sufficient native activity for plant growth and development. Expression of these cotton HPPD variants in Arabidopsis resulted in heightened herbicide resistance. These findings offer critical insights into the target amino acids of HPPD for gene editing, paving the way for the development of herbicide-resistant cotton in the future.
除草剂在提高作物产量方面发挥着关键作用，然而，抗除草剂杂草的出现以及作物对除草剂的敏感性对其功效构成了重大挑战。β-三酮类除草剂专门作用于对植物生长至关重要的4-羟基苯丙酮酸双加氧酶（HPPD）。值得注意的是，针对这类除草剂的抗性杂草很少被发现。在本研究中，我们旨在鉴定棉花HPPD基因中赋予对甲基磺草酮（一种广泛使用的三酮类除草剂）抗性的突变。通过在大肠杆菌中建立高通量突变筛选系统，我们鉴定出导致HPPD中氨基酸替换的四个单核苷酸变化，从而在保留天然酶活性的同时产生了对甲基磺草酮的抗性。这些突变的各种组合对除草剂抗性表现出协同效应。此外，HPPD变体能够互补拟南芥athppd突变体，表明它们保留了足够的天然活性以支持植物生长和发育。这些棉花HPPD变体在拟南芥中的表达导致了更高的除草剂抗性。这些发现为基因编辑中HPPD的目标氨基酸提供了关键见解，为未来抗除草剂棉花的开发铺平了道路。
