S.cn (Y.Y.) Institute of Plant Protection, Sichuan Academy of
S.cn (Y.Y.) Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China; [email protected] Correspondence: [email protected] (X.Z.); [email protected] (Y.L.); Tel.: +86-028-84590090 (X.Z.); +86-0571-63370333 (Y.L.) The initial two authors contributed equally to this work.Citation: Tang, W.; Liu, S.; Yu, X.; Yang, Y.; Zhou, X.; Lu, Y. The Basis of Tolerance Mechanism to Metsulfuron-Methyl in Roegneria kamoji (Triticeae: Poaceae). Plants 2021, ten, 1823. doi/ ten.3390/plants10091823 Academic Editor: Simon Hodge Received: three August 2021 Accepted: 29 August 2021 Published: 1 SeptemberAbstract: Roegneria kamoji, a perennial monocot weed that belongs towards the tribe Triticeae (loved ones: Poaceae), is definitely an emerging problematic weed in winter wheat (Triticum aestivum) fields in China. We have previously confirmed 4 R. kamoji populations tolerant to acetyl-CoA carboxylase (ACCase) inhibitors, and failed control of these populations by metsulfuron-methyl was observed. The objective of this study was to characterize the amount of tolerance to metsulfuron-methyl, the basis of tolerance mechanism, and cross-tolerance to acetolactate synthase (ALS) inhibitors in R. kamoji. A whole-plant dose esponse assay showed that plants of all R. kamoji populations (each from wheat fields and uncultivated regions) exhibited higher tolerance to metsulfuron-methyl, depending on their one hundred survival at 6-fold recommended field dose (RFD) and ED50 values six.84-fold RFD, no susceptible population was identified. Gene sequencing indicated that no reported amino acid substitutions related with resistance to ALS inhibitor had been found in the ALS gene among the R. kamoji populations. Pretreatment together with the recognized cytochrome P450 von Hippel-Lindau (VHL) Storage & Stability monooxygenases (CytP450) inhibitor malathion lowered the ED50 values of metsulfuron-methyl in two R. kamoji populations. These populations also exhibited crosstolerance to RFD of mesosulfuron-methyl and bispyribac-sodium. The activities of glutathione-Stransferase (GST) and CytP450 could possibly be induced by metsulfuron-methyl in R. kamoji, which can be related for the identified tolerant crop wheat. This can be the initial report elucidating metsulfuron-methyl tolerance in R. kamoji. The reversal of tolerance by malathion plus the GST and/or CytP450 enhanced herbicide metabolism suggests that non-target-site mechanisms confer tolerance to metsulfuron-methyl in R. kamoji. Key phrases: common Roegneria; ALS inhibitor; non-target website; cytochrome P450; glutathione S-transferasesPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.1. Introduction Roegneria kamoji is really a typical perennial weed that belongs to Roegneria in the tribe Triticeae (NF-κB Formulation Poaceae household). It can be widely distributed across China, Korea, and Japan, and is usually discovered in hillside, grassland, urban green spaces, and field borders [1,2]. In current years, R. kamoji has been identified spreading in winter wheat (Triticum aestivum) fields in Hubei, Anhui, and Zhejiang provinces of China (Supplemental Figure S1), and has become a dominant weed in some regions [3,4]. It has been the practice of several farmers to use acetyl-CoA carboxylases (EC 6.four.1.two, ACCase) inhibitors, including fenoxaprop-ethyl, clodinafop-propargyl, and pinoxaden for postemergence control of graminaceous weeds in wheat [5,6]. Failed handle of R. kamoji by fenoxaprop-ethyl was observed in each populations collected from wheat fields and uncultivated regions, which implies ther.