title: Inhibition of root meristem growth by cadmium involves nitric oxide-mediated repression of auxin accumulation and signalling in Arabidopsis.
abstract: The root is the first plant organ to get in contact with the toxin cadmium (Cd), which is a widespread soil contaminant. Cd inhibits the growth of the primary root, but the mechanisms underlying this inhibition remain elusive. In this study, we used physiological, pharmacological and genetic approaches to investigate the roles of nitric oxide (NO) and auxin in Cd-mediated inhibition of Arabidopsis thaliana root meristem growth. Our study demonstrated that in the first 12 h of exposure, Cd inhibits primary root elongation through a decrease in the sizes of both the elongation and meristematic zones. Following Cd exposure, a decrease in auxin levels is associated with reduced PIN1/3/7 protein accumulation, but not with reduced PIN1/3/7 transcript levels. Additionally, Cd stabilized AXR3/IAA17 protein to repress auxin signalling in this Cd-mediated process. Furthermore, decreasing Cd-induced NO accumulation with either NO-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) or NO synthase inhibitor N(ω) -nitro-l-Arg-methylester (l-NAME) compromised the Cd-mediated inhibition of root meristem development, reduction in auxin and PIN1/3/7 accumulation, as well as stabilization of AXR3/IAA17, indicating that NO participates in Cd-mediated inhibition of root meristem growth. Taken together, our data suggest that Cd inhibits root meristem growth by NO-mediated repression of auxin accumulation and signalling in Arabidopsis.
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University, Haikou, 570228, China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Yuan
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University, Haikou, 570228, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001565:Benzoates / Q000378:metabolism; D002104:Cadmium / Q000633:toxicity*; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D007093:Imidazoles / Q000378:metabolism; D007210:Indoleacetic Acids / Q000032:analysis / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000032:analysis / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D014157:Transcription Factors
chemical_list: C110728:AXR3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D001565:Benzoates; D007093:Imidazoles; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D014157:Transcription Factors; D002104:Cadmium; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester
keywords: AXR3/IAA17; Cd stress