title: Novel roles of hydrogen peroxide (H₂O₂) in regulating pectin synthesis and demethylesterification in the cell wall of rice (Oryza sativa) root tips.
abstract: Hydrogen peroxide (H₂O₂) has been reported to increase lignin formation, enhance cell wall rigidification, restrict cell expansion and inhibit root elongation. However, our results showed that it not only inhibited rice (Oryza sativa) root elongation, but also increased root diameter. No study has reported how and why H₂O₂ increases cell expansion and root diameter. Exogenous H₂O₂ and its scavenger 4-hydroxy-Tempo were applied to confirm the roles of H₂O₂. Immunofluorescence, fluorescence probe, ruthenium red staining, histological section and spectrophotometry were used to monitor changes in the degree of pectin methylesterification, pectin content, pectin methylesterase (PME) activity and H₂O₂ content. Exogenous H₂O₂ inhibited root elongation, but increased cell expansion and root diameter significantly. H₂O₂ not only increased the region of pectin synthesis and pectin content in root tips, but also increased PME activity and pectin demethylesterification. The scavenger 4-hydroxy-Tempo reduced root H₂O₂ content and recovered H₂O₂-induced increases in cell expansion and root diameter by inhibiting pectin synthesis, PME activity and pectin demethylesterification. H₂O₂ plays a novel role in the regulation of pectin synthesis, PME activity and pectin demethylesterification. H₂O₂ increases cell expansion and root diameter by increasing pectin content and demethylesterification.
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, 359 Tiyuchang Road, Hangzhou, 310006, China.|College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, 359 Tiyuchang Road, Hangzhou, 310006, China.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, 359 Tiyuchang Road, Hangzhou, 310006, China.
authors.forename: Guanfu
authors.initials: G
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, 359 Tiyuchang Road, Hangzhou, 310006, China.
authors.forename: Longxing
authors.initials: L
authors.lastname: Tao
mesh_terms: D050260:Carbohydrate Metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004951:Esterification; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D019811:Hydroxylamine / Q000494:pharmacology; D018519:Meristem / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D010368:Pectins / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018518:Plant Root Cap / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D003497:Cyclic N-Oxides; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D019811:Hydroxylamine; D010368:Pectins; D006861:Hydrogen Peroxide; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; C505333:TEMPOL-H
keywords: cell wall; hydrogen peroxide (H2O2); pectin; pectin methylesterase; reactive oxygen species; rice (Oryza sativa)