Resistance to glyphosate in Lolium rigidum

✍ Scribed by Lorraine-Colwill, Debrah F; Hawkes, Tim R; Williams, Patricia H; Warner, Simon AJ; Sutton, Peter B; Powles, Stephen B; Preston, Christopher

• Book ID: 101215524
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 122 KB
• Volume: 55
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(199904)55:4<489::aid-ps943>3.0.co;2-t

✦ Synopsis

Annual ryegrass (Lolium rigidum) is a widespread and important weed of Australia and populations of this weed have developed resistance to most major herbicides, including glyphosate. The possible mechanisms of resistance have been examined in one glyphosate-resistant Lolium population.

No major diþ erences were observed between resistant and susceptible biotypes in respect of (i) the target enzyme (EPSP synthase), (ii) DAHP synthase, the ürst enzyme of the target (shikimate) pathway, (iii) absorption of glyphosate, or (iv) translocation. Following treatment with glyphosate, there was greater accumulation of shikimate (derived from shikimate-3-Pi) in susceptible than in resistant plants. In addition, the resistant population exhibited cross-resistance to 2-hydroxy-3-(1,2,4-triazol-1-yl)propyl phosphonate, a herbicide which, although structurally similar to glyphosate, acts at an unrelated target site. On the basis of these observations we speculate that movement of glypho-