作     者：Shuan Han, Lin Fang, Xuejian Ren, Wenle Wang and Jing Jiang

刊物名称: New Phytologist

出版年份: 2014

卷:   期:   页码:

文章摘要 :

Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca2+ and H2O2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in  H2O2 - and Ca2+  -mediated root elongation.

Root elongation in seedlings of the loss-of-function mutant Atmpk6 (Arabidopsis thaliana MPK6) was less sensitive to moderate  H2O2 or ABA than that in wild-type (WT) plants. The enhanced elongation was a result of root cell expansion. This effect disappeared when ABAinduced  H2O2 accumulation or the cytosolic Ca2+  increase were defective.

Molecular and biochemical evidence showed that increased expression of the cell wall peroxidase PRX34 in Atmpk6 root cells enhanced apoplastic  H2O2 generation; this promoted a cytosolic Ca2+  increase and Ca2+   influx across the plasma membrane. The plasma membrane damage caused by high levels of  H2O2 was ameliorated in a Ca2+ -dependent manner.

These results suggested that there was intensified PRX34-mediated  H2O2 generation in the apoplast and increased Ca2+  flux into the cytosol of Atmpk6 root cells; that is, the spatial separation of apoplastic H2O2 from cytosolic Ca2+  in root cells prevented  H2O2 -induced inhibition of root elongation in Atmpk6 seedlings.