Cell Wall and Protoplast Isoperoxidases in Relation to Injury, Indoleacetic Acid, and Ethylene Effects

Abstract

In tobacco (Nicotiana Tabacum) pith, sweet potato (Ipomnoea batatas), and carrot (Daucus carota) storage roots, differences were found between cell wall and protoplast peroxidases in their isoenzyme patterns, activity, and reaction to tissue injury.In the pith of elongating tobacco internodes, 90% of total activity was associated with the walls, 80% of which was due to the ionically and covalently bound fractions. With senescence, the increase in activity occurred mainly in the protoplast and the free fraction in the walls. The major protoplast isoperoxidases formed the free wail fraction, and the minor ones formed the wail bound fractions. The minor isoperoxidases were the only ones whose activities were affected by cut injury. Neither senescence nor injury caused qualitative changes in the cell isoperoxidase pattern. In the potato root cells, the isoperoxidases were also distinctive in their distribution and in their reactions to injury as well as to ethylene.In potato and carrot roots, the wall fractions contributed 30 and 95 %, respectively, to total peroxidase activity. The injury-induced increase in peroxidase activity occurred mainly in the protoplast of tobacco pith and potato roots and almost entirely in the ionically bound fraction of the walls in carrot roots. Ethylene stimulated peroxidase development in potato roots, especially in the protoplast, but had no effect in either tobacco pith or carrot roots. Ethylene did not affect the inhibiting action of indoleacetic acid on peroxidase activity in tobacco pith, nor did indoleacetic acid significantly affect the stimulating action of ethylene in potato roots.Actinomycin D inhibited the injury-dependent development of peroxidase in tobacco pith, stimulated the injury-and ethylene-dependent peroxidase development in potato root, and had no effect on peroxidase development in carrot root. Cycloheximide prevented the increase in peroxidase activity in tobacco pith and potato root, but not in the carrot root. Thus, the enhancement of peroxidase activity resulted from either enzyme activation exclusively or front enzyme synthesis. RNA synthesis seems to be only indirectly related to isoperoxidase synthesis caused bv injury or ethylene.Previous investigation (5) (3,11,25,31) and its possible involvement in cell wall lignification and extensibility has been discussed in detail (10,20,32,35). Therefore, we extended our comparative studies to include the cell wall isoperoxidase fractions. This report deals with the interaction between injury and IAA, cycloheximide, or actinomycin D in the development of the soluble and cell wall bound isoperoxidases in the presence or absence of added ethylene or in the presence of mercuric perchlorate used to remove endogenous ethylene. The reported lack of reaction of carrot root-soluble peroxidase to added ethylene, in contrast to sweet potato root (36), prompted us to include the carrot root in this study. Special attention has been paid to the free peroxidase fraction in tobacco pith cell walls, since a significant r...

Differential Activity of Peroxidase Isozymes in Response to Wounding, Gypsy Moth, and Plant Hormones in Northern Red Oak (Quercus rubra L.)

“…In addition, generalized soluble or wall-bound POD activity increases in other plant species in response to wounding (Birecka and Miller, 1974;Kawaoka et al, 1994), pathogens (Bashan et al, 1987), salicylic acid (Rao et al, 1997), and jasmonates (Thaler et al, 1996;Moore et al, 2003). While JA and insect wounding have been found to elevate total soluble POD activity similarly (Choi et al, 1994;Tamari et al, 1995;Zhang and Baldwin, 1997), this study is among the first to suggest that various peroxidase isozymes may be differentially responsive to JA or other signals (Buzi et al, 2004) and the first to find insectresponsive POD isoforms.…”

“…Each plant species typically displays a unique pattern and number of soluble and wall-bound isozymes that may respond differentially to environmental stimuli. Some of the factors known to influence POD isozyme expression are mechanical wounding (Birecka and Miller, 1974;Svalheim and Robertsen, 1990), mite feeding (Bronner et al, 1991), pathogen infection (Lagrimini and Rothstein, 1987;Ye et al, 1990), plant hormones (Ridge and Osborne, 1970;Birecka and Miller, 1974;Neuman et al, 1992), and plant developmental stage (Pao and Morgan, 1988;Biles and Martyn, 1993).…”

“…Although POD functions have been well studied in tobacco, horseradish, and other herbaceous species (Birecka and Miller, 1974;Lagrimini and Rothstein, 1987;Kawaoka et al, 1994), activity studies in woody plants are uncommon (Goodin et al, 1993;Dowd et al, 1998a). Since insect attack elicits changes in leaf polyphenols in some oak species (e.g., Rossiter et al, 1988), it is likely that the activities of oak phenolic-oxidizing enzymes and isozymes also change in response to wounding.…”

Cell Wall and Protoplast Isoperoxidases in Tobacco Plants in Relation to Mechanical Injury and Infection with Tobacco Mosaic Virus

“…Procedures related to isolation of the protoplast and wall peroxidases were similar to those previously used (6). The Triton X-100 extracts showed traces or no peroxidase activity.…”

“…Previous study on Wisconsin 38 tobacco plant pith has shown a great increase of peroxidase activity, not only in its protoplast fraction, but also in the wall-bound fraction in response to cutting injury (6). Neither senescence nor injury caused qualitative changes in the cell isoperoxidase pattern.…”