The present invention concerns a method for modifying the growth characteristics of plants by modulating expression in a plant of a nucleic acid sequence encoding a GRUBX protein and/or modulating activity and/or levels in a plant of a GRUBX protein. The present invention furthermore provides novel GRUBX proteins and nucleic acids encoding such proteins. The invention also relates to constructs comprising GRUBX encoding nucleic acids, and transgenic plants having modified growth characteristics, which plants have modulated expression of a nucleic acid encoding a GRUBX protein.