Glufosinate‐ammonium: a review of the current state of knowledge

Abstract

Glufosinate is a key herbicide to manage glyphosate-resistant weeds mainly because it is a broad-spectrum herbicide, and transgenic glufosinate-resistant crops are available. Although glufosinate use has increased exponentially over the past decade, the treated area with this herbicide is far less than that with glyphosate. This is because glufosinate often provides inconsistent performance in the field, which is attributed to several factors including environmental conditions, application technology, and weed species. Glufosinate is also highly hydrophilic and does not translocate well in plants, generally providing poor control of grasses and perennial species. In the soil, glufosinate is rapidly degraded by microorganisms, leaving no residual activity. While there have been concerns regarding glufosinate toxicology, its proper use can be considered safe. Glufosinate is a fast-acting herbicide that was first discovered as a natural product, and is the only herbicide presently targeting glutamine synthetase. The mode of action of glufosinate has been controversial, and the causes for the rapid phytotoxicity have often been attributed to ammonia accumulation. Recent studies indicate that the contact activity of glufosinate results from the accumulation of reactive oxygen species and subsequent lipid peroxidation. Glufosinate disrupts both photorespiration and the light reactions of photosynthesis, leading to photoreduction of molecular oxygen, which generates reactive oxygen species. The new understanding of the mode of action provided new ideas to improve the herbicidal activity of glufosinate. Finally, a very few weed species have evolved glufosinate resistance in the field, and the resistance mechanisms are generally not well understood requiring further investigation.

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

“…This imbalance leads to accumulation of glyoxylate, which is a strong inhibitor of the ribulose-1,5bisphosphate carboxylase activase, necessary for the proper functioning of ribulose-1,5 bisphosphate carboxylase/oxygenase. Consequently, photosynthesis is inhibited (Wendler et al, 1992;Wild and Wendler, 1993;González-Moro et al, 1997), causing accumulation of ROS and cell death (reviewed by Hess, 2000, and more recently by Takano and Dayan, 2020).…”

Strategies for discovering resistance‐breaking, safe and sustainable commercial herbicides with novel modes of action and chemotypes

“…Predicting downstream effects for a hypothetical protein target is a challenge, evidenced by the fact that the exact mechanism of toxicity for well-established commercial products such as glyphosate and glufosinate is not fully understood, and new observations and insights are still being reported more than 40 years after their initial discovery. 23 In contrast, many medicines adjust human disease pharmacology to alleviate symptoms without the need to fully understand or cure the disease. Furthermore, pharmaceuticals have fewer cost of goods sold (COGS) challenges associated with the production of active ingredients (AIs) due to substantially higher profit margins compared to herbicides.…”

A Journal of the Plague Year

“…Several weed management topics are covered by front matter. A much‐needed update with new insights on glufosinate and its biochemical and physiological effects are provided in a review by Takano and Dayan 27 . Hall et al 28 .…”

“…A much-needed update with new insights on glufosinate and its biochemical and physiological effects are provided in a review by Takano and Dayan. 27 Hall et al 28 review the potential of unexploited enzyme targets for herbicides in amino acid synthesis pathways. A paper speculates on the potential for enhanced root exudation of herbicides as a mechanism of herbicide resistance.…”