VIEW ARTICLE

The Stabilization of Artificial and Natural Cell Wall Membranes by Phenolic Infusion and its Relation to Wilt Disease Resistance. C. H. Beckman, Professor, Dept. of Plant Pathology-Entomology, University of Rhode Island, Kingston 02881; W. C. Mueller(2), and M. E. Mace(3). (2)Associate Professor, Dept. of Plant Pathology-Entomology, University of Rhode Island, Kingston 02881; (3)Research Plant Pathologist, National Cotton Pathology Research Laboratory, College Station, Texas 77840. Phytopathology 64:1214-1220. Accepted for publication 18 April 1974. DOI: 10.1094/Phyto-64-1214.

Pectinase alone did not cause artificial calcium pectate-pectin membranes to swell. But these membranes did swell and eventually disintegrated when exposed to oxalate alone or, more rapidly, when exposed to a combination of oxalate and pectinase. They were also degraded, without apparent swelling, by Fusarium oxysporum, f. sp. cubense. These membranes became highly resistant to swelling and disintegration when infused with the oxidation products of the phenolic, 3-hydroxytyramine, either before or, to a lesser extent, during treatment. Natural perforation plates in banana root vessels were unaffected by oxalate + pectinase, or by F. oxysporum f. sp. cubense. They were caused to swell and became very fragile, however, following three to four cycles of low pH/high pH + oxalate. Phenolic infusion prevented the swelling of these natural perforation plates by such treatment. It is postulated that the phenolic infusion of infection sites, commonly associated with vascular browning, is a final step in a localization process that prevents systemic infection in many wilt disease-resistant plants. It is further postulated that this infusion of infection sites with phenolics may finally serve to insulate the infection from healthy surrounding tissue, thereby turning off host responses. The timing of phenolic infusion may be critical to the success or failure of defense responses, since too early an infusion may inhibit the processes necessary for localization; whereas, too late an infusion could permit degradation of the sealing-off structures and systemic distribution of the parasite.