title: The auxin conjugate indole-3-acetyl-aspartate affects responses to cadmium and salt stress in Pisum sativum L.
abstract: The synthesis of IAA-amino acid conjugates is one of the crucial regulatory mechanisms for the control of auxin activity during physiological and pathophysiological responses. Indole-3-acetyl-aspartate (IAA-Asp) is a low molecular weight amide conjugate that predominates in pea (Pisum sativum L.) tissues. IAA-Asp acts as an intermediate during the auxin degradation pathway. However, some recent investigations suggest a direct signaling function of this conjugate in various processes. In this study, we examine the effect of 100 μM IAA-Asp alone and in combination with salt stress (160 mM NaCl) or heavy metal stress (250 μM CdCl2) on H2O2 concentration, protein carbonylation as well as catalase and ascorbate (APX) and guaiacol peroxidase (GPX) activities in 7-day-old pea seedlings. As revealed by spectrophotometric analyses, IAA-Asp increased the carbonylated protein level and reduced the H2O2 concentration. Moreover, IAA-aspartate potentiated the effect of both Cd(2+) ions and NaCl on the H2O2 level. The enzymatic activities (catalase and peroxidases) were examined using spectrophotometric and native-PAGE assays. IAA-Asp alone did not affect catalase activity, whereas the two peroxidases were regulated differently. IAA-Asp reduced the APX activity during 48h cultivation. APX activity was potentiated by IAA-Asp+NaCl after 48h. Guaiacol peroxidase activity was diminished by all tested compounds. Based on these results, we suggest that IAA-Asp can directly and specifically affect the pea responses to abiotic stress.
authors.affiliation: Nicolaus Copernicus University, Department of Biochemistry, Lwowska 1 87-100 Torun, Poland. Electronic address: maciejost@umk.pl.
authors.forename: Maciej
authors.initials: M
authors.lastname: Ostrowski
authors.affiliation: Nicolaus Copernicus University, Department of Biochemistry, Lwowska 1 87-100 Torun, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Ciarkowska
authors.affiliation: Nicolaus Copernicus University, Department of Biochemistry, Lwowska 1 87-100 Torun, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Jakubowska
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006861:Hydrogen Peroxide / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D018532:Pisum sativum / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism; D050050:Protein Carbonylation / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D012965:Sodium Chloride / Q000633:toxicity*; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D007210:Indoleacetic Acids; D002104:Cadmium; C026984:indolyl-3-aspartic acid; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D002374:Catalase; D009195:Peroxidase
keywords: Ascorbate peroxidase; Auxin conjugate; Catalase; Guaiacol peroxidase; Heavy metal stress; Indole-3-acetyl-aspartate; P. sativum; Protein carbonylation; Salt stress