A Holistic Approach to Potato Suberin Analysis: A Time Travel from Breakdown Products to Suberin Deposition to Metabolite Profiling of Wound Periderm.

The outer skins of potato tubers undergo healing after the wounding that occurs during cultivation and processing of this major food crop, but the macromolecular structure of the suberized cell wall barriers that mitigate drought and infection has remained elusive. Because many prior models have drawn upon top-down analyses of depolymerization treatments that are known to be incomplete, we devised a comprehensive strategy of bottom-up monitoring of wound-healing metabolites at several time points, solid-state NMR (ssNMR) compositional analysis of the suberized cell wall, and top-down chemical analysis of soluble chemical depolymerization products. Liquid and gas chromatography - mass spectrometry (LC-MS and GC-MS) metabolite profiling were conducted for extracts from wound tissues in four potato cultivars with differing skin morphologies at 0, 1, 2, 3, and 7 days post wounding. In parallel, 13C ssNMR was used to characterize the suberin-enriched polymeric material. Finally, the biopolymer composite was subjected to mild chemical breakdown followed by LC-MS and GC-MS analyses. By coordinating these phytochemical analyses, we found new glycoalkaloid, sterol, and phenolic amine compounds that are incorporated within the biopolymer composite. These findings enrich our picture of the suberin macromolecular structure that develops after wounding or in native skins to protect potato tubers from environmental threats.