title: Morphological and biochemical behavior of fenugreek (Trigonella foenum-graecum) under copper stress.
abstract: The effects of copper on germination and growth of fenugreek (Trigonella foenum-graecum) was investigated separately using different concentrations of CuSO₄. The germination percentage and radical length had different responses to cupric ions: the root growth increased with increasing copper concentration up to 1 mM Cu²⁺ and was inhibited thereafter. In contrast, the germination percentage was largely unaffected by concentrations of copper below 10 mM. The reduction in root growth may have been due to inhibition of hydrolytic enzymes such as amylase. Indeed, the average total amylolytic activity decreased from the first day of treatment with [Cu²⁺] greater than 1 mM. Furthermore, copper affected various plant growth parameters. Copper accumulation was markedly higher in roots as compared to shoots. While both showed a gradual decrease in growth, this was more pronounced in roots than in leaves and in stems. Excess copper induced an increase in the rate of hydrogen peroxide (H₂O₂) production and lipid peroxidation in all plant parts, indicating oxidative stress. This redox stress affected leaf chlorophyll and carotenoid content which decreased in response to augmented Cu levels. Additionally, the activities of proteins involved in reactive oxygen species (ROS) detoxification were affected. Cu stress elevated the ascorbate peroxidase (APX) activity more than two times at 10 mM CuSO₄. In contrast, superoxide dismutase (SOD) and catalase (CAT) levels showed only minor variations, only at 1 mM Cu²⁺. Likewise, total phenol and flavonoid contents were strongly induced by low concentrations of copper, consistent with the role of these potent antioxidants in scavenging ROS such as H₂O₂, but returned to control levels or below at high [Cu²⁺]. Taken together, these results indicate a fundamental shift in the plant response to copper toxicity at low versus high concentrations.
authors.affiliation: Laboratoire des Biotechnologies Végétales Appliquées à l'Amélioration des Cultures, Faculté des Science de Sfax, Université de Sfax BP 1171, Sfax 3000, Tunisia. Electronic address: A.Elleuch@hotmail.com.
authors.forename: Amine
authors.initials: A
authors.lastname: Elleuch
authors.forename: Zayneb
authors.initials: Z
authors.lastname: Chaâbene
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Grubb
authors.forename: Noureddine
authors.initials: N
authors.lastname: Drira
authors.forename: Hafedh
authors.initials: H
authors.lastname: Mejdoub
authors.forename: Bassem
authors.initials: B
authors.lastname: Khemakhem
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003300:Copper / Q000494:pharmacology*; D018525:Germination / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D029910:Trigonella / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D002734:Chlorophyll; D003300:Copper; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase
keywords: APX; Amylase; Antioxidants; CAT; DTT; Germination; Growth; H(2)O(2); MDA; NBT; Nitrobluetetrazolium; Oxidative stress; ROS; SOD; TBA; TCA; ascorbate peroxidase; catalase; dithiothreitol; hydrogen peroxide; malondialdehyde; reactive oxygen species; superoxide dismutase; thiobarbituric acid; trichloroacetic acid