American sloughgrass (Beckmannia syzigachne Steud.) has become a dominant weed in fields with rice-wheat rotation. Moreover, herbicide resistance has rendered weed control difficult. We identified a biotype showing resistance to ALS inhibitor mesosulfuron-methyl with a resistant index 3.3, but without any ALS mutation. This study aims to identify and confirm the factors associated with non-target site resistance of this biotype to mesosulfuron-methyl using RNA-Seq. 118,111 unigenes were assembled, and 50.9% of these were annotated across seven databases. Eleven contigs related to metabolic resistance were identified based on differential expression via RNA-Seq which include a novel resistance-related transcription factor (MYC3) and two disease resistance proteins were also identified (At1g58602 and At1g15890). Fold changes in expression of these genes in comparison M-R vs. M-S ranged from 3.9 to 11.6, as confirmed by qPCR. The expression of a contig annotated as cytochrome P450 (CYP86B1) in resistant individuals was over 3 times higher than that in sensitive individuals at 0-72 h after mesosulfuron-methyl treatment. A similar trend was noted for three other genes annotated as glutathione S-transferase (GST), namely GST-T3, GST-U6, and GST-U14; the expression of GST-U6 in resistant individuals was up to 142.3 times higher than that in sensitive individuals at 24 h after mesosulfuron-methyl treatment. In addition, GST activity in resistant individuals was 2.1 to 5.3 times higher than that in sensitive individuals. The GR50 of resistant biotype decreased from 24.4 to 11.3 g a.i. ha-1 after P450 inhibitor malathion treatment. This study identified a cytochrome P450 gene CYP86B1 and three GST genes GST-T3, GST-U6, and GST-U14 that have higher expression in mesosulfuron-methyl resistant B. syzigachne, suggesting that both P450- and GST-based activities could be involved in resistance.

中文翻译：

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用 RNA-Seq 转录组分析来鉴定与 Beckmannia syzigachne 中基于非靶位点的 mesosulfuron-methyl 抗性相关的候选基因

美国旱草（Beckmannia syzigachne Steud.）已成为稻麦轮作田间的优势杂草。此外，除草剂抗性使杂草控制变得困难。我们确定了一种对 ALS 抑制剂甲基磺隆具有抗性的生物型，抗性指数为 3.3，但没有任何 ALS 突变。本研究旨在使用 RNA-Seq 鉴定和确认与该生物型对甲磺隆的非靶位点抗性相关的因素。组装了 118,111 个 unigenes，其中 50.9% 在七个数据库中进行了注释。基于通过 RNA-Seq 的差异表达鉴定了 11 个与代谢抗性相关的重叠群，其中包括一个新的抗性相关转录因子 (MYC3) 和两个抗病蛋白 (At1g58602 和 At1g15890)。比较 MR 与 MS，这些基因表达的倍数变化范围从 3.9 到 11.6，正如 qPCR 所证实的那样。在甲磺隆处理后 0-72 小时，耐药个体中注释为细胞色素 P450 (CYP86B1) 的重叠群的表达比敏感个体高 3 倍以上。其他三个注释为谷胱甘肽 S-转移酶 (GST) 的基因也有类似的趋势，即 GST-T3、GST-U6 和 GST-U14；甲磺隆处理后24 h，耐药个体中GST-U6的表达比敏感个体高142.3倍。此外，耐药个体的 GST 活性比敏感个体高 2.1 至 5.3 倍。在 P450 抑制剂马拉硫磷处理后，耐药生物型的 GR50 从 24.4 g ai ha-1 下降到 11.3 g ai ha-1。