Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2003
Publication Date: 1/5/2004
Citation: Sabba, R.P., Lulai, E.C. 2004. Immunocytological comparison of native and wound periderm maturation in potato tuber. American Journal Of Potato Research. 81:119-124.
Interpretive Summary: The skin of native and wound periderm forms a barrier at the surface of potato tubers that protects the vegetable from infection and dehydration. An immature periderm is susceptible to skinning injury, which leads to potato loses in storage and decreased market quality for consumers. As the periderm matures, it becomes resistant to skinning injury. The potato skin is created by a single layer of cells called the phellogen (cork cambium). Changes in the architecture of the phellogen cell walls upon periderm maturation are directly associated with development of resistance to skinning injury. The walls of phellogen cells are thin and labile to fracture in immature potato periderm, but thicken and become resistant to fracture upon maturation. Many of the biochemical processes associated with development of native and wound periderm are similar. Consequently, wound periderm development is often used as a convenient model for year-round research on the biochemical processes associated with native periderm development during growth. However, little research has been done to compare the biochemical steps involved in the maturation of the two types of periderm. Here we show that staining with toluidine blue O can be used as a tool to distinguish between the skin and phellogen cell layers in native and wound periderm. However, immunolabeling with antibodies which react with pectin biopolymers in the cell wall of native and wound periderm reveal some differences between these two types of dermal tissues. These immunological differences are particularly noteworthy in the phellogen layer, where the development of resistance to skinning injury takes place. These results indicate that, although wound periderm is a versatile and widely used research model, there are at least a few biochemical dissimilarities to native periderm. Differences such as those noted in this research must be considered when using the wound periderm model to study native periderm maturation.
Technical Abstract: The maturation of potato (Solanum tuberosum L.) tuber periderm and the wound periderm, which develops to replace the native periderm when it is damaged, are agriculturally important processes which are poorly understood. While both types of periderm form from a phellogen layer which serves as a lateral meristem, there has been little research done on comparing the biochemical processes and steps involved in the maturation of the two types of periderm. Here we demonstrate that toluidine blue O is useful for distinguishing between suberized and non-suberized cells in both native and wound periderm. We demonstrated previously that maturation of native periderm and resistance to excoriation (skinning) is accompanied by an increase in relatively un-esterified and esterified homogalacturonan polymers in the walls of phellogen cells. However, here we show that there is no similar immunologically detectable increase in homogalacturonan polymers in the walls of phellogen cells accompanying wound periderm maturation. These results demonstrate that the biochemical processes responsible for maturation and resistance to excoriation differ between native and wound periderm. This dissimilarity between wound and native periderm maturation demonstrates the potential limitations in applying the wound periderm model to research on native periderm.