A two‐step control of basic and acidic peroxidases and its significance for growth and development

Abstract

A generalized two‐step and interdependent control of basic and acidic peroxidases (EC 1.11.1.7) is observed in plant responses to different physical and chemical stimuli. An interpretative model consisting of a pathway of reactions is presented on the basis of our own data and the literature. Stress‐induced membrane depolarization would generate different species of free radicals and peroxides, which in turn initiate lipid peroxidation. The degradation of cell membranes is suggested to bring about rapid changes in ionic fluxes (especially release of K+ which would result in an enhanced endogenous Ca/K ratio) and in leakage of solutes (among them electron donors such as ascorbic acid and phenolic substances). The increased intracellular relative calcium level results in: 1) activated secretion of basic peroxidases into the free space where, in association with the electron donors and maybe with the circulating indole‐3‐acetic acid (IAA), they eliminate the peroxides; and 2) facilitated binding of basic peroxidases to membrane structures allowing a role as 1‐aminocyclopropane‐1‐carboxylic acid (ACC)‐oxidases. The resulting IAA and ACC oxidase‐mediated changes in ethylene production would further induce (this time through the protein synthesis machinery) an increase in activity of phenylalanine ammonia‐lyase (EC 4.31.5) and acidic peroxidases. The resulting lignification and cell wall rigidification determines the growth and/or the developmental response to the initial stress.

Ethylene Production in Spinach Leaves during Floral Induction

“…In spinach, it was previously shown that flowering induction is characterized by an increase of the total peroxidase activity and of the acid/basic ratio (Penel and Greppin, 1975). These changes in peroxidases and those reported here for ethylene are very similar to those described in various plant tissues in response to different types of stresses, for instance, mechanical perturbation (Boyer and De Jaegher, 1986) indicating relations between changes in ethylene and in cellular distribution of peroxidases (Gaspar, Penel, Castillo, and Greppin, 1985). This leads us to propose that flowering induction could be considered as a stress response of the plants to a change in their light regime.…”

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

“…Four increased in activity over time (C9.4, A4.4, A4.1, and A3.9), while the other two decreased (A4.2 and A4.0). Peroxidase isozymes in many other plant species are known to be developmentally regulated (Gaspar et al, 1985), but it is not possible to assign developmental roles to red oak PODs without knowing their specific functions. Some isoforms that increased in activity during our study may have been involved in lignification of the developing leaves (Gaspar et al, 1985;Díaz and Merino, 1998).…”

“…Although the exact functions of anionic isozymes in red oak are unknown, their induction by wounding is consistent with responses to insects (Felton et al, 1992, Arnason et al, 1994, Dowd, 1994Dowd et al, 1998a,b). Anionic PODs have been implicated in a variety of leaftoughening responses, such as lignin biosynthesis (Gaspar et al, 1985;Díaz and Merino, 1998), suberization (Espelie et al, 1986;McDougall, 1993), and crosslinking of cell walls and extensin polymers (Ridge and Osborne, 1970;Everdeen et al, 1988;Bostock and Stermer, 1989). Such toughening processes may decrease the nutritional quality of the plant tissue for herbivores (Bi et al, 1997) as well as prevent secondary pathogen infection (Vance et al, 1980;Bostock and Stermer, 1989).…”

“…Other plant responses include lignification (Vance et al, 1980;Díaz and Merino, 1998) and the production of pathogenesis-related (PR) proteins (Van Loon, 1985). PODs comprise one important class of PR proteins (PR-9) implicated in these "defense responses," in which an important role is to catalyze the formation of phenolic radicals at the expense of H 2 O 2 (Gaspar et al, 1985). PODs may also oxidize phenolic monomers to form lignin (Siegel, 1954;Mäder et al, 1980;Grisebach, 1981), function in H 2 O 2 production (Elstner and Heupel, 1976;Mäder et al, 1980), and metabolize indole acetic acid (Endo, 1968;Mato et al, 1988).…”

The Role of Hydrogen Peroxide-Producing and Hydrogen Peroxide-Consuming Peroxidases in the Leaf Apoplast of Cowpea in Manganese Tolerance

“…1; Fecht-Christoffers et al, 2003a). The release of acidic isoenzymes was attributed to a late response to several stresses (Gaspar et al, 1985;Castillo, 1986), catalyzing the typical H 2 O 2 -consuming peroxidatic cycle. Therefore, released acidic PODs probably catalyze the formation of brown depositions in the cell wall.…”