The marketability and price of fresh market potatoes are being determined by tuber appearance: shiny and smooth looking tubers sell well while tubers with russeted skin or skinning injuries do not (Fig. 1). Russeting refers to thickening and cracking of the skin, resulting in an earthy appearance of the tuber, and loss of the typical pigmentation. Skinning injuries refer to peeling of the skin during harvest, which exposes the tuber flesh. These skin disorders are not caused by pathogens[1]. Potato growth displays a strong interaction effect between genotype and environment, and suboptimal growth conditions - such as high temperature[2], soil composition or insufficient fertilizers - are often associated with impaired skin development. In addition to determining the appearance of potatoes, smooth and intact skin is an important factor in preventing tuber water loss, greening and pathogen invasion[3], and consequently, the quality of stored tubers.