Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/1998
Publication Date: N/A
Technical Abstract: The susceptibility of potatoes to skinning injury during harvest is widespread and results in costly disease and blemish problems; however, little is known about the physiology associated with the development of resistance to skinning. We have examined periderm cells (phellem, phellogen and phelloderm) of immature (susceptible to skinning) and mature (resistant to skinning) tubers from genetically diverse cultivars to identify the specific types of cells and ultrastructural changes associated with susceptibility and resistance to skinning. Together with previous results, we found that skinning injury was characterized by a separation of the phellem tissue (suberized periderm cells) from the tuber. This separation always occurred by fracture of radial cell walls within the phellogen. The fragile nature of these radial cell walls in immature tubers is marked by their thinness. During periderm maturation, the phellogen becomes inactive and its cell walls thicken. As the radial walls of the phellogen thicken they often take on a snake like curvature and become more resistant to fracture. These changes appear to be at least part of the cellular basis for skin-set development. Upon periderm maturation, suberin aliphatics are laid down on the inner tangential walls of the layer of phellem cells that neighbor the phellogen. Unlike other phellem cell walls, these inner tangential walls do not possess histochemically detectable amounts of suberin phenolics. Our results suggest that the physiological processes associated with the maturation and strengthening of phellogen cell walls are of great importance in reducing wounding and related diseases and blemishes in potatoes.