The present invention describes genes and methods for the isolation of genes which encode gene products which, if not present, lead to a greatly delayed growth and/or complete standstill of growth of Arabidopsis thaliana at the seedling level. The invention describes the use of these genes and gene products encoded by them for the discovery of novel herbicides. In addition, the present invention describes the use of the genes and gene products identified herein for the generation of plants which are resistant to herbicides. The present invention also relates to a method for identifying herbicidally active substances, to substances identified by this method and to their use as herbicides. The invention furthermore relates to nucleic acid constructs, vectors, organisms comprising the nucleic acid constructs and/or vectors, specifically transgenic plants comprising the nucleic acid constructs and/or vectors. Moreover, the invention relates to a method for identifying antagonists and to their use, antibodies and antisense RNA molecules and compositions comprising a herbicidal substance isolated by the methods according to the invention. Furthermore, the invention realtes to compositions comprising the antibody, the antisense nucleic acid and/or the antagonist.