Abscisic Acid Induces Mitogen-Activated Protein Kinase Activation in Barley Aleurone Protoplasts

Abstract

Abscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein phosphorylation by MAP kinase immunoprecipitates, increased after 1 min, peaked after 3 min, and decreased to basal levels after ~5 min of ABA treatment in vivo. Antibodies recognizing phosphorylated tyrosine residues precipitate with myelin basic protein kinase activity that has identical ABA activation characteristics and demonstrate that tyrosine phosphorylation of MAP kinase occurs during activation. The half-maximal concentration of ABA required for MAP kinase activation, 3 x 10-7 M, is very similar to that required for ABA-induced rab16 gene expression. The tyrosine phosphatase inhibitor phenylarsine oxide can completely block ABA-induced MAP kinase activation and rab16 gene expression. These results lead us to conclude that ABA activates MAP kinase via a tyrosine phosphatase and that these steps are a prerequisite for ABA induction of rab16 gene expression.

Gene Expression and Signal Transduction in Water-Stress Response

“…These results indicate that a protein phosphorylation and dephosphorylation process might be involved in ABAresponsive signaling during water deficit. Recently, ABA was shown to induce a rapid and transient activation of MAPK in barley aleurone protoplasts (Knetsch et al, 1996). Correlation between ABA-induced MAPK activation and ABA-induced gene expression implies that MAPK might be involved in ABA signal transduction (Fig.…”

Abscisic Acid Biosynthesis and Response

“…The "early" genes include those encoding members of a MAPK cascade, some of which are induced within 1-10 min of stress or ABA treatment, as well as transcription factors and early response to dehydration (erd) genes (reviewed in Shinozaki and Yamaguchi-Shinozaki, 2000;Xiong and Zhu, 2001). It is noteworthy that many of the genes encoding presumed signaling components show relatively specific induction by drought, cold, salinity, wounding or osmotic stress, but only one of these has been shown to be ABA-responsive (Knetsch et al, 1996). Similarly although ABA signaling can be mediated by inositol 1,4,5-triphosphate, hyperosmotic stress induces a rapid and transient increase in IP 3 independent of abscisic acid in Arabidopsis cell culture (Takahashi et al, 2001).…”

MAP kinases MPK9 and MPK12 are preferentially expressed in guard cells and positively regulate ROS-mediated ABA signaling

“…ABA was shown to induce MAPK activation in barley aleurone layers (14), and a possible MAPK activity was observed in Vicia guard cell protoplasts (15). Furthermore, a study with pea epidermal peels showed that the MAPKK inhibitor PD98059 inhibits ABA-induced stomatal closure and expression of an ABA-inducible dehydrin gene (16,17).…”