Soybean MAPK, GMK1 Is Dually Regulated by Phosphatidic Acid and Hydrogen Peroxide and Translocated to Nucleus during Salt Stress

Abstract

Mitogen-activated protein kinase (MAPK) is activated by various biotic and abiotic stresses. Salt stress induces two well-characterized MAPK activating signaling molecules, phosphatidic acid (PA) via phospholipase D and phospholipase C, and reactive oxygen species (ROS) via nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase. In our previous study, the activity of soybean MAPK, GMK1 was strongly induced within 5 min of 300 mM NaCl treatment and this early activity was regulated by PA. In this study, we focused on the regulation of GMK1 at the later stage of the salt stress, because its activity was strongly persistent for up to 30 min. H(2)O(2) activated GMK1 even in the presence of PA generation inhibitors, but GMK1 activity was greatly decreased in the presence of diphenyleneiodonium, an inhibitor of NADPH-oxidase after 5 min of the treatment. On the contrary, the n-butanol and neomycin reduced GMK1 activity within 5 min of the treatment. Thus, GMK1 activity may be sustained by H(2)O(2) 10 min after the treatment. Further, GMK1 was translocated into the nucleus 60 min after NaCl treatment. In the relationship between GMK1 and ROS generation, ROS generation was reduced by SB202190, a MAPK inhibitor, but was increased in protoplast overexpressing TESD-GMKK1. However, these effects were occurred at prolonged time of NaCl treatment. These data suggest that GMK1 indirectly regulates ROS generation. Taken together, we propose that soybean GMK1 is dually regulated by PA and H(2)O(2) at a time dependant manner and translocated to the nucleus by the salt stress signal.

SALT-RESPONSIVE ERF1 Regulates Reactive Oxygen Species-Dependent Signaling during the Initial Response to Salt Stress in Rice

“…When key players are present within the cell, a quick initial response is guaranteed. Moreover, nuclear translocation of activated MAPK proteins has been observed during abiotic stress (Ahlfors et al, 2004;Im et al, 2012), keeping MAPK and potential nuclear target TFs separated under control conditions. This first ROS wave is propagated at the transcriptional level through SERF1.…”

Transcriptomic Profiling of Soybean in Response to High-Intensity UV-B Irradiation Reveals Stress Defense Signaling

“…PA binding to ABI1 helps tether it to the plasma membrane where it interact with ATHB6, a negative regulator of ABA signaling involved in stomatal closure in response to drought and salinity stress (Zhang et al, 2004). PA also can bind to and activate MAPK in the response of A. thaliana and soybean to salt stress (Yu et al, 2010; Im et al, 2012). Based on the current results, ROS generation induced by UV-B stress is more likely dependent on SOD than on NADPH oxidase, even though PLD-derived PA binds to and activates NADPH oxidases under environmental stress (Park et al, 2004; Zhang et al, 2009).…”

Plant phosphoinositide-dependent phospholipases C: Variations around a canonical theme

“…Rapid calcium release into the cytosol in response to salt and osmotic stress observed in Arabidopsis root tips [96], seedlings [102] and tobacco cells [109] was shown to be dependent on PI-PLC. PI-PLCs affect several cellular processes in hyperosmotic stress conditions including microtubule polymer recovery in plasmolyzed wheat root cells [108], rapid MAPK activation and ROS generation in soybean [110], release of Tubby transcriptional factors from the plasma membrane [111] and the control of phosphoenolpyruvate carboxylase kinase 1 gene expression in sorghum [112].…”

“…In Arabidopsis, PA binds and mediates membrane recruitment of glyceraldehyde 3-phosphate dehydrogenase, clathrin heavy chain proteins and sucrose non-fermenting-1-related protein kinase 2 during salt stress [164][165]. PA activates calcium-dependent protein kinase [166], MAP kinase GMK1 [110] and monogalactosyldiacylglycerol synthase [167]. In contrast, inhibition of actin-capping proteins [168] and protein phosphatase 1 [169] by PA has been reported.…”