The invention relates to a method for testing a plant or plant part for exhibiting a reduced or absent wound-induced surface discolouration as compared to a control plant or plant part, which method comprises providing a plant or plant part that is obtained from a plant population that shows genetic variation, in particular a gene bank； optionally creating a wound surface on the plant or plant part； incubating the plant or plant part or the wound surfaces created thereon to allow for discolouration to occur therein or thereon； observing the discolouration in or on the plants or plant parts； comparing the observed discolouration with the discolouration that is observed in the control plant or plant part to assess whether the plant or plant part shows no discolouration or a discolouration that is reduced as compared to the control plant or plant part； and identifying a plant or plant part that shows no discolouration or a discolouration that is reduced as compared to the control plant or plant part as a plant that harbours the reduced wound-induced surface discolouration trait.
