title: Exposure of iron nanoparticles to Arabidopsis thaliana enhances root elongation by triggering cell wall loosening.
abstract: In this study, we investigated the effect of nZVI on plant root elongation in Arabidopsis thaliana and showed, for the first time, that nZVI enhanced root elongation by inducing OH radical-induced cell wall loosening. Exposure of plants to 0.5 g/L nZVI enhanced root elongation by 150-200% over that in the control, and further mechanistic studies showed that this occurred via nZVI-mediated OH radical-induced cell wall loosening. The oxidation capacity of nZVI, leading to release of H2O2, allowed it to cause OH radical-induced cell wall loosening in roots. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometers (MALDI-TOFMS)-based analysis clearly revealed that pectin-polysaccharides in roots were degraded; they are one of the main matrix-polysaccharide-connecting and load-bearing polymers in cell walls. Rapid root elongation led to structural changes in root cell walls: reduction of cell wall thickness and a bias on the orientation of cellulose microfibrils. Additionally, the asymmetrical distribution of tensional strength resulted from the OH radical-induced cell wall loosening enhanced endocytosis. These findings emphasize that OH radical-induced cell wall loosening is important for mechanical regulation of the cell wall and provide new insights into the cellular responses of plants exposed to reactive metal nanoparticles.
authors.affiliation: School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH) , Pohang 790-784, Republic of Korea.
authors.forename: Jae-Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Yongjik
authors.initials: Y
authors.lastname: Lee
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Kim
authors.forename: Sungmin
authors.initials: S
authors.lastname: Gu
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Sohn
authors.forename: Young Sook
authors.initials: YS
authors.lastname: Seo
authors.forename: Hyun Joo
authors.initials: HJ
authors.lastname: An
authors.forename: Yoon-Seok
authors.initials: YS
authors.lastname: Chang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development; D002473:Cell Wall / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism; D007501:Iron / Q000008:administration & dosage* / Q000737:chemistry; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D008954:Models, Biological; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development
chemical_list: D006861:Hydrogen Peroxide; D007501:Iron