The invention relates to a method for testing a plant or plant part for exhibiting a reduced or absent wound-induced surface discoloration 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 discoloration to occur therein or thereon; observing the discoloration in or on the plants or plant parts; comparing the observed discoloration with the discoloration that is observed in the control plant or plant part to assess whether the plant or plant part shows no discoloration or a discoloration that is reduced as compared to the control plant or plant part; and identifying a plant or plant part that shows no discoloration or a discoloration that is reduced as compared to the control plant or plant part as a plant that harbors the reduced wound-induced surface discoloration trait.