Non-target-Site Resistance in Lolium spp. Globally: A Review

Abstract

The Lolium genus encompasses many species that colonize a variety of disturbed and non-disturbed environments. Lolium perenne L. spp. perenne, L. perenne L. spp. multiflorum, and L. rigidum are of particular interest to weed scientists because of their ability to thrive in agricultural and non-agricultural areas. Herbicides are the main tool to control these weeds; however, Lolium spp. populations have evolved multiple- and cross-resistance to at least 14 herbicide mechanisms of action in more than 21 countries, with reports of multiple herbicide resistance to at least seven mechanisms of action in a single population. In this review, we summarize what is currently known about non-target-site resistance in Lolium spp. to acetyl CoA carboxylase, acetohydroxyacid synthase, microtubule assembly, photosystem II, 5-enolpyruvylshikimate-3-phosphate synthase, glutamine synthetase, very-long chain fatty acids, and photosystem I inhibitors. We suggest research topics that need to be addressed, as well as strategies to further our knowledge and uncover the mechanisms of non-target-site resistance in Lolium spp.

Evidence of multiple origins of glyphosate resistance evolution in Lolium multiflorum

“…For example, we detected genes involved in the detoxification of xenobiotics, most notably cytochrome P450 genes. Genes in this family have been suggested to be involved in glyphosate resistance by enhancing herbicide degradation in other populations of L. multiflorum, L. rigidum , and L. perenne outside of Oregon (Suzukawa et al, 2021). In addition, we identified genes involved in transmembrane transport (Supporting Information Table S4).…”

“…Vacuolar sequestration of glyphosate has been suggested to confer resistance in other species (Peng et al, 2010). Although much research has been conducted to elucidate non-target-site resistance mechanisms to glyphosate in L. multiflorum and other weed species, the genetic and molecular mechanisms remain largely unknown (Suzukawa et al, 2021).…”

“…Elucidating the molecular mechanisms of herbicide resistance is crucial for the improvement of weed management practices. Although target-site resistance has been described frequently for many herbicides with different mechanisms of action, the underlying molecular characteristics that confer non-target-site resistance remain largely unknown (Baucom, 2016; Suzukawa et al, 2021). Identification of the genetic changes involved in resistance evolution will allow the development of quick herbicide resistance diagnostics in the laboratory and in the field.…”

“…However, recent research has shown that the resistance phenotype can be explained by major-effect genes, such as enhanced expression of the P450 CYP81A10v7 that conferred resistance to seven herbicide chemistries (Han et al, 2021). While physiological modifications that lead to NTSR in weeds are well documented, the genetic basis of the modifications are poorly understood (Suzukawa et al, 2021).…”

“…L. multiflorum has evolved resistance to many herbicides (Suzukawa et al, 2021). For example, a population collected from a prune orchard in California exhibited resistance to four different mechanisms of action (Brunharo & Hanson, 2018).…”