Provided is a method for screening a population of plants or mushrooms, or parts thereof for the presence therein of individuals that show a reduced discolouration as compared to a control plant, mushroom or part thereof, which method comprises a) providing a population of plants, mushrooms or parts thereof from the population； b) creating a wound surface on the plants, mushrooms or parts thereof； c) incubating the plant, mushrooms or parts thereof or the wound surfaces created thereon in an aqueous environment or with a colouring substrate to allow for discoloration to occur therein or thereon； d) observing the wound-induced discolouration in or on the plants, mushrooms or parts thereof； e) comparing the observed discolouration with the discolouration that is observed in the control plant, mushroom or part thereof to identify plants, mushrooms or parts thereof that show no discolouration or a discolouration that is reduced as compared to the control plant, mushroom or part thereof, wherein the plants or mushrooms, or parts thereof used in the screen are of a developmental stage different from, or a tissue other than the stage or tissue in which discolouration occurs； and f) selecting the plants, mushrooms or parts thereof that show no discolouration or a discolouration that is reduced as compared to the control plant, mushroom or parts thereof. The colouring sensitive substrate can be chlorogenic acid, catechol, caffeic acid and DOPA, among others.
