Glutamine synthetase mutation conferring target‐site‐based resistance to glufosinate in soybean cell selections

Abstract

Changes in sensitivity to glufosinate have been related to mutations at the binding site of the herbicide on the glutamine synthetase. His(249) is one of the residues implicated in the binding domain for the substrate and inhibitor, and hence the exchange of this residue with tyrosine plays a role in lowering the sensitivity of the mutated enzyme.

Target‐site mutation associated with glufosinate resistance in Italian ryegrass (Lolium perenne L. ssp. multiflorum)

“…These results suggest that the resistance to glufosinate in the population MG is conferred by an altered GS enzyme. Similar results were reported in soybean and mungbean ( Vigna radiata L.) glufosinate‐resistant cells 14, 15. The selected glufosinate‐resistant cells required between 2.6 and 4.5 times greater glufosinate concentration than the susceptible cells to inhibit the GS enzyme activity by 50%, indicating that an altered target site was responsible for the resistance.…”

“…On average, the susceptible populations C1 and C2 accumulated 1.6 times more ammonia than the resistant population. The strong relationship between dose response and ammonia accumulation has been reported in rice,13 soybean ( Glycine max L.) cell cultures14 and Italian ryegrass,20 confirming that ammonia accumulation is directly related to glufosinate toxicity.…”

“…There are several amino acid substitutions previously reported for the GS gene that are involved in reduced GS sensitivity. Sixteen, eight and 10 amino acid substitutions have been reported in glufosinate‐resistant cells of soybean,14 mungbean15 and maize17 respectively. However, the amino acid substitution found in Italian ryegrass in this study has not been reported.…”

“…Differential responses in sensitivity to glufosinate in weed and crop species have been attributed to three main mechanisms: altered uptake, reduced translocation and GS overproduction 10–13. Several mutations in the GS gene that confer glufosinate resistance have been reported in cell cultures 14–17. In these studies, an insensitive GS was involved in glufosinate resistance.…”

Characterization of de novo transcriptome for waterhemp (Amaranthus tuberculatus) using GS‐FLX 454 pyrosequencing and its application for studies of herbicide target‐site genes

“…GS genes have been isolated from a number of plant species, as observed from the sequences deposited in GenBank. Genes that are responsible for GS activity in plants studied to date are part of a multigene family that encode cytosolic and chloroplastic forms 40, 41. Genes for GS subunits are also among the best conserved sequences in plants 42.…”