MPK6 controls H2O2- induced root elongation by.........
题目：MPK6 controls H
2- induced root elongation by mediating Ca
2+influx across the plasma membrane of root cells in Arabidopsi seedlings
AtMPK6; abscisic acid (ABA); apoplastic H2O2 increase; cell wall peroxidase34; cytosolic C 2+ rise; plasma membrane Ca2+ channels; root elongation
：Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca(2+) and H
2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in H
2 - 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 H
2 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 H
2 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 H
2 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 H
2 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 H
2 from cytosolic Ca(2+) in root cells prevented H
2 -induced inhibition of root elongation in Atmpk6 seedlings.