title: MPK6 controls H2 O2-induced root elongation by mediating Ca2+ influx across the plasma membrane of root cells in Arabidopsis seedlings.
abstract: Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca(2+) and H2 O2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in H2 O2 - and Ca(2+) -mediated root elongation. Root elongation in seedlings of the loss-of-function mutant Atmpk6 (Arabidopsis thaliana MPK6) was less sensitive to moderate H2 O2 or ABA than that in wild-type (WT) plants. The enhanced elongation was a result of root cell expansion. This effect disappeared when ABA-induced H2 O2 accumulation or the cytosolic Ca(2+) increase were defective. Molecular and biochemical evidence showed that increased expression of the cell wall peroxidase PRX34 in Atmpk6 root cells enhanced apoplastic H2 O2 generation; this promoted a cytosolic Ca(2+) increase and Ca(2+) influx across the plasma membrane. The plasma membrane damage caused by high levels of H2 O2 was ameliorated in a Ca(2+) -dependent manner. These results suggested that there was intensified PRX34-mediated H2 O2 generation in the apoplast and increased Ca(2+) flux into the cytosol of Atmpk6 root cells; that is, the spatial separation of apoplastic H2 O2 from cytosolic Ca(2+) in root cells prevented H2 O2 -induced inhibition of root elongation in Atmpk6 seedlings.
authors.affiliation: State Key Laboratory of Cotton Biology, College of Life Sciences, Henan University, Jinming Street, Kaifeng, Henan, 475004, China.
authors.forename: Shuan
authors.initials: S
authors.lastname: Han
authors.forename: Lin
authors.initials: L
authors.lastname: Fang
authors.forename: Xuejian
authors.initials: X
authors.lastname: Ren
authors.forename: Wenle
authors.initials: W
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D010544:Peroxidases; C553803:PRX34 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium
keywords: AtMPK6; abscisic acid (ABA); apoplastic H2O2 increase; cell wall peroxidase34; cytosolic Ca2+ rise; plasma membrane Ca2+ channels; root elongation