Hada Zeineb, Menchari Yosra, Rojano-Delgado Antonia M, Torra Joel, Menéndez Julio, Palma-Bautista Candelario, de Prado Rafael, Souissi Thouraya
Department of Plant Health and Environment, National Institute of Agronomy of Tunisia, University of Carthage, Tunis, Tunisia.
Laboratory of Bioagressor and Integrated Management in Agriculture (LR14AGR02), National Institute of Agronomy of Tunisia, University of Carthage, Tunis, Tunisia.
Front Plant Sci. 2021 Apr 1;12:626702. doi: 10.3389/fpls.2021.626702. eCollection 2021.
Resistance to acetolactate synthase (ALS) inhibiting herbicides has recently been reported in from wheat fields in northern Tunisia, where the weed is widespread. However, potential resistance mechanisms conferring resistance in these populations are unknown. The aim of this research was to study target-site resistance (TSR) and non-target-site resistance (NTSR) mechanisms present in two putative resistant (R) populations. Dose-response experiments, ALS enzyme activity assays, ALS gene sequencing, absorption and translocation experiments with radiolabeled herbicides, and metabolism experiments were carried out for this purpose. Whole plant trials confirmed high resistance levels to tribenuron and cross-resistance to florasulam and imazamox. ALS enzyme activity further confirmed cross-resistance to these three herbicides and also to bispyribac, but not to flucarbazone. Sequence analysis revealed the presence of amino acid substitutions in positions 197, 376, and 574 of the target enzyme. Among the NTSR mechanisms investigated, absorption or translocation did not contribute to resistance, while evidences of the presence of enhanced metabolism were provided. A pretreatment with the cytochrome P450 monooxygenase (P450) inhibitor malathion partially synergized with imazamox in post-emergence but not with tribenuron in dose-response experiments. Additionally, an imazamox hydroxyl metabolite was detected in both R populations in metabolism experiments, which disappeared with the pretreatment with malathion. This study confirms the evolution of cross-resistance to ALS inhibiting herbicides in from Tunisia through TSR and NTSR mechanisms. The presence of enhanced metabolism involving P450 is threatening the chemical management of this weed in Tunisian wheat fields, since it might confer cross-resistance to other sites of action.
最近有报道称突尼斯北部麦田中的杂草对乙酰乳酸合酶（ALS）抑制型除草剂产生了抗性，该杂草在当地广泛分布。然而，这些种群产生抗性的潜在机制尚不清楚。本研究的目的是研究两个假定的抗性（R）种群中存在的靶标位点抗性（TSR）和非靶标位点抗性（NTSR）机制。为此进行了剂量反应试验、ALS酶活性测定、ALS基因测序、放射性标记除草剂的吸收和转运试验以及代谢试验。整株试验证实了对苯磺隆的高抗性水平以及对唑嘧磺草胺和甲氧咪草烟的交叉抗性。ALS酶活性进一步证实了对这三种除草剂以及双草醚的交叉抗性，但对氟唑磺隆没有交叉抗性。序列分析显示靶标酶的第197、376和574位存在氨基酸取代。在所研究的NTSR机制中，吸收或转运对抗性没有贡献，但提供了增强代谢存在的证据。在剂量反应试验中，用细胞色素P450单加氧酶（P450）抑制剂马拉硫磷进行预处理，在苗后与甲氧咪草烟部分协同，但与苯磺隆没有协同作用。此外，在代谢试验中，两个R种群中均检测到甲氧咪草烟羟基代谢物，用马拉硫磷预处理后该代谢物消失。本研究证实了突尼斯的杂草通过TSR和NTSR机制对ALS抑制型除草剂产生交叉抗性的演变。涉及P450的增强代谢的存在正在威胁突尼斯麦田中这种杂草的化学防治，因为它可能赋予对其他作用位点的交叉抗性。
