Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2000
Publication Date: N/A
Technical Abstract: Native periderm, the dermal tissue covering the potato tuber, provides an essential barrier to pathogens and dehydration. The cell walls of the outer group of peridermal cells, phellem cells, are laminated with suberin, a complex, inert biopolyester, which provides a protective barrier for the tuber. Suberin is composed of two distinctly different biochemical components: a polyphenolic component and a polyaliphatic component. Wounding induces new depositions of these suberin components as part of wound-periderm development during wound-healing. Rapid suberization of wounded areas is essential to avoid infection. We have investigated processes that may be involved in the regulation of suberization. Delay of suberin polyphenolic accumulation inhibited subsequent suberin polyaliphatic accumulation. Certain periderm and wound related compounds were found to have drastic effects on suberin polyphenolic accumulation. Coumarins, which have been shown by others to be present in native perider and possibly linked to some peridermal diseases, were potent inhibitors of suberin polyphenolic accumulation during wound-healing. However, transmission electron microscopic analysis of coumarin-treated tissues showed that the primary cell walls were ultrastructurally modified. These results indicate that wounding induces cell wall modifications independent of suberin accumulation. The coumarin esculetin inhibited peroxidase activity, an enzyme thought to be involved in suberin polyphenolic accumulation. Soluble phenolics extracted from esculetin-treated tuber wounds differed from those isolated from control tissues. These results are important in determining what factors influence and regulate suberization and the development of resistance to infection.