Aldo‐keto reductase enzymes detoxify glyphosate and improve herbicide resistance in plants

Abstract

SummaryIn recent years, concerns about the use of glyphosate‐resistant crops have increased because of glyphosate residual levels in plants and development of herbicide‐resistant weeds. In spite of identifying glyphosate‐detoxifying genes from microorganisms, the plant mechanism to detoxify glyphosate has not been studied. We characterized an aldo‐keto reductase gene from Pseudomonas (PsAKR1) and rice (OsAKR1) and showed, by docking studies, both PsAKR1 and OsAKR1 can efficiently bind to glyphosate. Silencing AKR1 homologues in rice and Nicotiana benthamiana or mutation of AKR1 in yeast and Arabidopsis showed increased sensitivity to glyphosate. External application of AKR proteins rescued glyphosate‐mediated cucumber seedling growth inhibition. Regeneration of tobacco transgenic lines expressing PsAKR1 or OsAKRI on glyphosate suggests that AKR can be used as selectable marker to develop transgenic crops. PsAKR1‐ or OsAKRI‐expressing tobacco and rice transgenic plants showed improved tolerance to glyphosate with reduced accumulation of shikimic acid without affecting the normal photosynthetic rates. These results suggested that AKR1 when overexpressed detoxifies glyphosate in planta.

Codeinone reductase isoforms with differential stability, efficiency and product selectivity in opium poppy

“…Codeinone reductases display the conserved AKR catalytic tetrad (D51, Y56, K86, H119) and mediate activity via an α/β barrel motif binding NADP(H) (Jez et al ., ). Plant AKRs play diverse physiological roles including in defense and the stress response, biosynthesis of osmolytes and membrane transport (Tang et al ., ; Kanayama et al ., ; Turóczy et al ., ; Vemanna et al ., ). Currently, COR and 1,2‐dehydroreticuline reductase (DRR) are the two known AKRs involved in BIA metabolism (Unterlinner et al ., ; Farrow et al ., ; Winzer et al ., ).…”

Enhanced Metabolic Degradation: The Last Evolved Glyphosate Resistance Mechanism of Weeds?

“…This AKR protein has little similarity to GOX and Gly oxidase of microbes that generate AMPA and glyoxylate from glyphosate. Vemanna et al (2017) had already shown that overexpression of transgenes of Pseudomonas and rice encoding AKR provides glyphosate resistance in tobacco (Nicotiana tabacum), and that silencing or mutating AKR genes in both plants and microbes increased sensitivity to glyphosate. These findings provided the clue that evolution of enhanced expression of an AKR gene in a weed could provide glyphosate resistance.…”

A novel TIPT double mutation in EPSPS conferring glyphosate resistance in tetraploid Bidens subalternans

“…b). Another study suggested that overexpressing aldo‐keto reductase enzymes in rice and tobacco could enhance glyphosate tolerance possibly through metabolism . However, the evolution of glyphosate metabolism in plants is rare and has been reported for only a few plants such as soybean, and the possibility of whether or not metabolism contributes to evolved glyphosate resistance in weeds remains to be proven …”