IS IT LIGNIN WE FIND ON THE PATH TO RESISTANCE?

Authors: Stange, Richard; Meadows, Frederick; KIM, HOON - UNIV OF WISCONSIN; Ralph, John; Himmelsbach, David; McCollum, Thomas

Submitted to: International Congress on Molecular Plant-Microbe Interactions
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: On the path leading to plant health in plant-pathogen interactions, a common landmark is the appearance of a material that turns red in phloroglucinol-HCl (PG-HCl). Observed in many plant species, this material is commonly identified as lignin, but is it? The PG-HCl reacting material from pectinase-elicited squash fruit was purified using cell wall hydrolases and solvent extractions. When the purified material is refluxed in water, p-coumaryl aldehyde (p-CA) is released. This finding is not typical of any described lignin, but the presence of p-CA may account for the material's histochemical reactions. Purified material was subjected to sequential extraction by refluxing in water and dioxane-water until almost no p-CA was released. This residue was subjected to acidolysis, and yielded both p-CA plus products potentially derived from P-subunit lignin beta-ethers. Solid-state NMR spectra of the purified material were collected using 13C cross-polarization magic-angle spinning. Initial data indicate that p-CA may be present in the purified material, although most of it was probably removed by extraction. However, a comparison of the spectra to the spectrum of 4-hydroxy cinnamic acid, suggests that either acid or ester forms derived from p-CA could be contained in the isolates. The latter would be consistent with suberin that is synthesized after wounding and would be present associated with carbohydrates. If we knew better what the landmarks were, we would have a better understanding of the path leading to disease resistance.