Key role for a glutathione transferase in multiple-herbicide resistance in grass weeds

Abstract

Multiple-herbicide resistance (MHR) in black-grass ( Alopecurus myosuroides ) and annual rye-grass ( Lolium rigidum ) is a global problem leading to a loss of chemical weed control in cereal crops. Although poorly understood, in common with multiple-drug resistance (MDR) in tumors, MHR is associated with an enhanced ability to detoxify xenobiotics. In humans, MDR is linked to the overexpression of a pi class glutathione transferase (GSTP1), which has both detoxification and signaling functions in promoting drug resistance. In both annual rye-grass and black-grass, MHR was also associated with the increased expression of an evolutionarily distinct plant phi (F) GSTF1 that had a restricted ability to detoxify herbicides. When the black-grass A. myosuroides ( Am ) Am GSTF1 was expressed in Arabidopsis thaliana, the transgenic plants acquired resistance to multiple herbicides and showed similar changes in their secondary, xenobiotic, and antioxidant metabolism to those determined in MHR weeds. Transcriptome array experiments showed that these changes in biochemistry were not due to changes in gene expression. Rather, Am GSTF1 exerted a direct regulatory control on metabolism that led to an accumulation of protective flavonoids. Further evidence for a key role for this protein in MHR was obtained by showing that the GSTP1- and MDR-inhibiting pharmacophore 4-chloro-7-nitro-benzoxadiazole was also active toward Am GSTF1 and helped restore herbicide control in MHR black-grass. These studies demonstrate a central role for specific GSTFs in MHR in weeds that has parallels with similar roles for unrelated GSTs in MDR in humans and shows their potential as targets for chemical intervention in resistant weed management.

Differential Responses to Preemergence and Postemergence Atrazine in Two Atrazine‐Resistant Waterhemp Populations

“…populations from Europe (Cummins et al, 2013). Results from this study indicated NBD-Cl effectively increased the activity of POST herbicides that are rapidly metabolized by GST enzymes as the main mechanism conferring resistance in A. myosuroides (Cummins et al, 2013), which could also provide a potential new option for regaining atrazine POST activity in MCR, ACR, and other MHR waterhemp populations. However, use of NBD-Cl to increase atrazine POST activity or to enhance the activity of PRE residual herbicides metabolized by GSTs has not been reported.…”

De Novo Genome Assembly of the Economically Important Weed Horseweed Using Integrated Data from Multiple Sequencing Platforms

“…), velvet bean (Mucuna pruriens), and wild radish (Raphanus raphanistrum; Mueller et al, 2003;Feng et al, 2004;Main et al, 2004;Zelaya et al, 2004;Koger and Reddy, 2005;Owen and Zelaya 2005;Preston and Wakelin, 2008;Ge et al, 2010Ge et al, , 2012Riar et al, 2011;Rojano-Delgado et al, 2012;Vila-Aiub et al, 2012;Ashworth et al, 2014;Sammons and Gaines, 2014). Physiologically, we know that non-target-site resistance can involve a plethora of metabolic, conversion, sequestration, and reduced translocation processes, including oxidation, conjugation, or compartmentation of the herbicide molecules (Yuan et al, 2007;Cummins et al, 2013;Iwakami et al, 2014). Horseweed represents a model weedy plant with a nontarget-site glyphosate-resistant mechanism via altered translocation or transport (Feng et al, 2004;Stewart et al, 2009;Ge et al, 2010).…”

Differential Expression of Genes Associated With Degradation Enhancement of Imazethapyr in Barnyardgrass (Echinochloa crus-galli)

“…GST genes encode enzymes that catalyze conjugation reactions of herbicides with more soluble molecules, decreasing the phytotoxicity of the compounds (Yuan et al, 2007),. These enzymes also have other functions in herbicide detoxification, such as peroxidase activity and stress signaling (Dixon et al, 2002;Powles & Yu, 2010;Cummins et al, 2013). The GSTF1 gene conferred greater tolerance to the herbicides chlorotoluron and fenoxaprop-P-ethyl in A. myosuroides and L. rigidum, causing multiple resistance (Cummins et al, 2013).…”

“…These enzymes also have other functions in herbicide detoxification, such as peroxidase activity and stress signaling (Dixon et al, 2002;Powles & Yu, 2010;Cummins et al, 2013). The GSTF1 gene conferred greater tolerance to the herbicides chlorotoluron and fenoxaprop-P-ethyl in A. myosuroides and L. rigidum, causing multiple resistance (Cummins et al, 2013). In rice, overexpression of the GSTL1 or GSTL2 genes led to greater tolerance to chlorsulfuron and glyphosate (Hu, Qv, Xiao, & Huang, 2009;Hu, 2014).…”