FOLLOWING SUBERIZATION IN POTATO WOUND PERIDERM BY HISTOCHEMICAL AND SOLID-STATE C-13 NUCLEAR-MAGNETIC-RESONANCE METHODS

The time course of suberization in wound periderm from potato (Solanum tuberosum L.) has been monitored by histochemical and high-resolution solid-state nuclear magnetic resonance (NMR) methods. Light microscopy conducted after selective staining of the lipid and double-bonded constituents shows that suberin is deposited at the outermost intact cell-wall surface during the first 7 d of wound healing; suberization forms a barrier to tissue infiltration at later times. Cross polarization-magic angle spinning C-13 NMR spectra demonstrate the deposition of a polyester containing all major suberin functional groups after just 4 d of wound healing. initially the suberin includes a large proportion of aromatic groups and fairly short aliphatic chains, but the spectral data demonstrate the growing dominance of long-chain species during the period 7 to 14 d after wounding. The results of preliminary C-13-labeling experiments with sodium [2-C-13]acetate and DL-[1-C-13]phenylalanine provide an excellent prospectus for future NMR-based studies of suberin biosynthesis.