Sphingosine-1-phosphate (S1P) mediates darkness-induced stomatal closure through raising cytosol pH and hydrogen peroxide (H2O2) levels in guard cells in Vicia faba

Abstract

The role and signaling of sphingosine-1-phosphate (S1P) during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S1P and hydrogen peroxide (H 2 O 2 ) levels and closed stomata. These darkness effects were significantly suppressed by DL-threo-dihydrosphingosine (DL-threo-DHS) and N,N-dimethylsphingosine (DMS), two inhibitors of long-chain base kinases. Exogenous S1P led to stomatal closure and H 2 O 2 production, and the effects of S1P were largely prevented by the H 2 O 2 modulators ascorbic acid, catalase, and diphenyleneiodonium. These results indicated that S1P mediated darkness-induced stomatal closure by triggering H 2 O 2 production. In addition, DL-threo-DHS and DMS significantly suppressed both darkness-induced cytosolic alkalization in guard cells and stomatal closure. Exogenous S1P caused cytosolic alkalization and stomatal closure, which could be largely abolished by butyric acid. These results demonstrated that S1P synthesis was necessary for cytosolic alkalization during stomatal closure caused by darkness. Furthermore, together with the data described above, inhibition of darkness-induced H 2 O 2 production by butyric acid revealed that S1P synthesis-induced cytosolic alkalization was a prerequisite for H 2 O 2 production during stomatal closure caused by darkness, a conclusion supported by the facts that the pH increase caused by exogenous S1P had a shorter lag and peaked faster than H 2 O 2 levels and that butyric acid prevented exogenous S1P-induced H 2 O 2 production. Altogether, our data suggested that darkness induced S1P synthesis, causing cytosolic alkalization and subsequent H 2 O 2 production, finally leading to stomatal closure.sphingosine-1-phosphate, cytosol pH, hydrogen peroxide, darkness, stomatal closure Citation:Ma Y L, She X P, Yang S S. Sphingosine-1-phosphate (S1P) mediates darkness-induced stomatal closure through raising cytosol pH and hydrogen peroxide (H 2 O 2 ) levels in guard cells in Vicia faba. Sci China Life Sci, 2012, 55: 974 -983,

Role of Cytoplasmic Alkalization and Nitric Oxide in Ethylene-induced Stomatal Closure in Arabidopsis

“…4). The data support the conclusion of time course study (Suhita et al, 2004;Gonugunta et al, 2008;Ma et al, 2012Ma et al, , 2013. Together with the data that cytosolic alkalization and NO mediate stomata closing by ethylene (Fig.…”

“…1), further provide genetic evidence for the vital role of cytosol alkalization and NO in stomata closing by ethylene. Cytosol alkalization and NO synthesis participate in ABA-, MJ-and light/darkness transition-led stomata closing (García-Mata and Lamattina, 2002;Suhita et al, 2004;Ma et al, 2012) our results here suggest that cytosol alkalization and NO are common signal transduction event during stomatal closure by multiple stimuli, including ethylene.…”

“…This relevance between cytosolic pH changes and stomatal movement suggests that guard cells cytosolic pH plays role in stomatal movement. Significantly, several studies have shown that guard cell cytosolic alkalization mediate stomata closing by ABA-, methyl jasmonate (MJ)and light/darkness transition (Suhita et al, 2004;Ma et al, 2012), while cytosolic pH reduction is involved in stomata opening caused by indole-3-acetic acid (IAA)-, kinetin-and fusicoccin (FC) (Irving et al, 1992;Suhita et al, 2004;Gonugunta et al, 2008). The data supports that cytoplasmic pH changes, as important signaling event are implicated in stomatal movement by different stimuli.…”

“…By means of comparing the time course of cytosolic pH and ROS or NO alterations in guard cells, cytoplasmic alkalization has been shown to be an essential prerequisite for ROS and NO production during ABA-, MJ-and light/darkness transition-induced stomatal closing (Suhita et al, 2004;Gonugunta et al, 2008;Ma et al, 2012Ma et al, , 2013. NO detection requires the formation of DAF-2 from DAF-2 DA a frequently used method of pH detection is based on BCECF protonation/deprotonation (Islam et al, 2010).…”

“…As previously described by Ma et al (2012) and Shi et al (2015), fluorescent indicator dye DAF-2 DA, ACC, butyric acid, methylamine, SNP, BCECF-AM, MES and c-PTIO were purchased from Sigma-Aldrich, whereas DMSO was from Amresco (Solon, OH and US). The remaining agents were from various suppliers of Chinese companies.…”