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Physiology and Biochemistry

Enzymatic Maceration of Plant Tissues by Endo-Pectin Lyase and Endo-Polygalacturonase from Aspergillus japonicus. Shigetaka Ishii, Senior Research Scientist, Central Research Laboratories, Kikkoman Shoyu Co., Ltd., 399 Noda, Noda-shi, Chibaken, Japan; Phytopathology 66:281-289. Accepted for publication 30 September 1975. DOI: 10.1094/Phyto-66-281.

Aspergillus japonicus produces endo-pectin lyase and endo-polygalacturonase as the main pectin depolymerases. The two enzymes differed in ability to macerate tissues of different plant species. Endo-pectin lyase most rapidly macerated onion tissue, while endo-polygalacturonase was most effective on radish tissue. Potato tissues were similarly macerated by the two enzymes. Susceptibility of plant tissues to maceration by the enzymes may depend largely on the enzyme specificity but not enzymes concentration. There were also differences between the two enzymes in the effect of pH and calcium ions on macerating activity. The two enzymes apparently differed in ability to release pectic substances from plant cell walls. The pectic substances extractable with 0.05 N NaOH, which are commonly referred to as protopectins, were accessible to endo-pectin lyase, while those extractable with 0.5% ammonium oxalate were accessible to endo-polygalacturonase. The relationship between the susceptibility of plant tissue to maceration by the two enzymes and the susceptibility of each pectic substance in the cell wall to attack by the enzymes may suggest the type of pectic substance that is important in cell wall cementing.