TY - JOUR T1 - Restricted Herbicide Translocation Was Found in Two Glyphosate-resistant Italian Ryegrass (Lolium multiflorum Lam.) Populations from New Zealand TT - JF - mdrsjrns JO - mdrsjrns VL - 18 IS - 4 UR - http://jast.modares.ac.ir/article-23-3456-en.html Y1 - 2016 SP - 1041 EP - 1051 KW - EPSP synthase mutation KW - Glyphosate KW - Herbicide resistance KW - Mechanism of resistance KW - Weeds N2 - Glyphosate resistance has been found in two populations of Italian ryegrass (Lolium multiflorum) following many years of glyphosate application in New Zealand vineyards. Dose-response experiments showed that both glyphosate-resistant Italian ryegrass populations had 10-fold levels of resistance to glyphosate compared to a susceptible population. Possible mechanisms of glyphosate resistance target site mutation at position Pro-106 of 5-enolpyruvyl-shikimate-3-phosphate synthase gene and alterations in glyphosate absorption/translocation in these populations were investigated. Genotyping assays demonstrated that there was no point mutation at Codon 106 of the 5-enolpyruvyl-shikimate-3-phosphate synthase gene in either of the resistant populations. Glyphosate-resistant and susceptible populations did not differ in 14C-glyphosate absorption. However, in both resistant populations, much more of the absorbed 14C-glyphosate was retained in the treated leaf than occurred in the susceptible population. Significantly more 14C-glyphosate was found in the pseudostem region of susceptible plants than resistant plants. Based on these results, it was suggested that alterations in glyphosate translocation patterns plays a major role in glyphosate resistance for Italian ryegrass populations from these New Zealand vineyards. M3 ER -