Effects of cadmium and copper on peroxidase, NADH oxidase and IAA oxidase activities in cell wall, soluble and microsomal membrane fractions of pea roots.
Twelve-day-old seedlings of pea (Pisum sativum L.) that were treated for 4 days by 20 and 100 micromol/l Cd(NO3)2 or CuSO4 showed a growth reduction in all organs. From root protein extracts, the activities of guaiacol peroxidase (GPX; EC 1.11.1.7), ascorbate peroxidase (APX; EC 1.11.1.11), coniferyl alcohol peroxidase (CAPX), NADH oxidase, and indole-3-acetic acid (IAA) oxidase were measured in covalently--and ionically--[symbol: see text] bound cell wall, soluble, and microsomal membrane fractions. With the exception of 20 micromol/l Cu, metal treatments enhanced GPX activity in all fractions. Only IAA oxidase activity was metal-elevated in the covalently bound cell wall fraction, while the ionic one showed Cd stimulation for all assayed enzymic activities. These effects were not entirely observed in Cu-treated plants, since APX and IAA oxidase activities were only enhanced in this fraction. However, soluble extract showed stimulation of APX activity, while in the microsomal fraction metal exposure also increased the activities of CAPX and NADH oxidase. Differential responses of root cell fractions to the presence of cadmium and copper ions are discussed in regard to the contribution of their enzymic capacities in antioxidant, lignification, and auxin degradation pathways. Comparisons between metals and dose effects are also underlined.
Chaoui
Abdelilah
A
Faculté des Sciences de Bizerte, Bio-Physiologie Cellulaires, Département des Sciences de la vie, 7021-Zarzouna, Tunisia.
Jarrar
Brahim
B
El Ferjani
Ezzedine
E
D019187:Cadmium Compounds / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects; D019327:Copper Sulfate / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects; D008861:Microsomes / Q000187:drug effects; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009566:Nitrates / Q000494:pharmacology*; D018532:Pisum sativum / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D010544:Peroxidases / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000254:growth & development
D019187:Cadmium Compounds; D009097:Multienzyme Complexes; D009566:Nitrates; C027929:indoleacetic acid oxidase; D010544:Peroxidases; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D019327:Copper Sulfate; C035196:cadmium nitrate