Relative expression levels of ACCase ( a ) and GSTL ( b ) in resistant versus sensitive plants. UBQ, TUB and GADPH were used for normalisation. Each measurement consists of two repetitions. BEFORE, before herbicide application; +2.5H and +6H, 2.5 and 6 h after herbicide application, respectively; AFTER, after herbicide application (2.5H and +6H); TOTAL, all samples. p values for differences in gene expression are given in brackets.