Relationship Between Pink Eye Symptoms and Cell Damage in the Tuber Periderm and Cortex
2008
Sabba, Robert P. | Bussan, Alvin J. | Lulai, Edward C.
Pink eye (PE) is a tuber disorder that leads to processing complications and bud-end rot in storage. Despite the significance of PE for the potato processing industry, limited progress has been made in understanding the physiological basis of this disorder. Although the internal autofluorescence that characterizes PE has been described, the external symptoms of PE have not been well characterized or correlated with internal cellular symptoms. It is of vital importance to determine the physiological and cytological effects of PE in order to understand how it is caused and to develop effective management strategies to prevent the disorder. External symptoms progressed from pinkish discoloration around tuber eyes to water-soaked and corky patch lesions. Internal symptoms progressed from erratic browning around cortical cell walls to necrotic zones and cells with dark, circular inclusions. These areas often became surrounded by an internal PE-related periderm, while the native periderm often became compromised or lost. Vital staining with fluorescein diacetate showed that cortical and periderm cells underneath the native phellem became non-viable in PE tissue. Immunolocalization of homogalacturonan and extensin epitopes indicated that these cell wall polymers were not altered in pink eye afflicted tissues. These results conclusively show that the PE disorder results in or is caused by cell death in tissue underneath the native phellem, but does not lead to either cell wall breakdown or extensin deposition which is often characteristic of pathogen activity.
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