The aim is to identify and catalogue those genes that are responsible for the enzymatic degradation of herbicidal active substances in resistant genotypes. The resistance is based on an unspecific intensification of the plant´s detoxification metabolism and can affect many different genes. It is known that genes involved in so-called metabolic herbicide resistance have significantly increased mRNA levels. By means of comparative transcriptome analyses these genes are quantified. In comparison of resistant and sensitive plants, significant changes in the mRNA levels are sought and identified and validated via correlation analyses between expression levels and herbologically well-characterized resistance phenotypes of candidate genes. Such genes are useful for agriculture as predictive molecular markers from which novel diagnostic tools can be developed for faster and more specific characterisation of field herbicide resistance in blackgrass.