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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING POTATO MARKET QUALITY THROUGH POSTHARVEST PHYSIOLOGY

Location: Sugarbeet and Potato Research

Title: Pink Eye: An Unusual Periderm Disorder Characterized by Compromized Periderm, Abberrant Suberization and Related Susceptibility to Infection

Authors
item Lulai, Edward
item Weiland, John
item Suttle, Jeffrey

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2006
Publication Date: July 1, 2006
Citation: Lulai, E.C., Weiland, J.J., Suttle, J.C. 2006. Pink eye: An unusual periderm disorder characterized by compromized periderm, abberrant suberization and related susceptibility to infection [abstract.] Potato Association of America/Solanacae 2006 Program & Abstracts. Abstract No. 301. p.206.

Technical Abstract: Potato tuber Pink Eye (PE) is a disorder of unknown origin that results in significant postharvest quality deterioration and rot. Little is known about the physiology of PE, including the characteristic tissue autofluorescence (AF) that defines the PE syndrome. The objective of this research was to identify the source of PE induced AF and PE related susceptibility to infection. The suberized barrier of the native periderm and neighboring tissues were investigated to determine their role in the PE disorder. The results showed that the integrity of the suberized barrier of the native periderm was compromised or in some places absent in PE tubers. The PE complex was further characterized by induction of unusual and erratic suberin poly(phenolic) (SPP) accumulations in the cortical parenchyma followed by latent suberin poly(aliphatic) (SPA) accumulations. Both accumulations were generally insufficient to form a complete barrier that was competent to block infections by bacteria and fungi. These anomalies and deficiencies generally started at the bud end of the tuber, leaving these and other PE-afflicted areas without a comprehensive barrier to infection, as evidenced by the presence of Rhizoctonia solani hyphae in a few samples. PE afflicted areas had high water vapor conductances, putatively due to the absence of suberin associated waxes; water vapor losses are known to cause tuber shrinkage and flaccidity. Widespread erratic accumulations of SPP on cortical parenchyma cell walls were found to be the source of AF commonly used to detect PE. The results of this study provide convincing evidence that PE is a physiological disorder in which the native periderm is disrupted in the growing tuber and internal suberization is induced. The compromised native periderm and the incomplete internal suberization lack the integrity to provide an effective barrier to infections. This may explain the inconsistent association of various pathogens with PE.

Last Modified: 7/30/2014
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