RESUMO
Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9-1 and mpk12-1 single mutants as well as wild-type plants, but not in mpk9-1 mpk12-1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA-induced stomatal closure in wild-type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9-1, mpk12-1 and mpk9-1 mpk12-1 mutants, as well in wild-type plants. Furthermore, MeJA triggered elevation of cytosolic Ca(2+) concentration ([Ca(2+)]cyt ) in the mpk9-1 mpk12-1 double mutant as well as wild-type plants. Activation of S-type anion channels by MeJA was impaired in mpk9-1 mpk12-1. Together, these results indicate that MPK9 and MPK12 function upstream of S-type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca(2+)]cyt elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Cálcio/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Transdução de Sinais , Ácido Abscísico/metabolismo , Acetatos/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/genética , Ciclopentanos/metabolismo , Citosol/química , Citosol/metabolismo , Flavonoides/farmacologia , Concentração de Íons de Hidrogênio , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/genética , Mutação , Óxido Nítrico/metabolismo , Oxilipinas/metabolismo , Estômatos de Plantas/enzimologia , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
We report that two mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate abscisic acid (ABA)-induced stomatal closure in Arabidopsis thaliana. Yeast elicitor (YEL) induced stomatal closure accompanied by intracellular reactive oxygen species (ROS) accumulation and cytosolic free calcium concentration ([Ca(2+) ]cyt ) oscillation. In this study, we examined whether these two MAP kinases are involved in YEL-induced stomatal closure using MAPKK inhibitors, PD98059 and U0126, and MAPK mutants, mpk9, mpk12 and mpk9 mpk12. Both PD98059 and U0126 inhibited YEL-induced stomatal closure. YEL induced stomatal closure in the mpk9 and mpk12 mutants but not in the mpk9 mpk12 mutant, suggesting that a MAPK cascade involving MPK9 and MPK12 functions in guard cell YEL signalling. However, YEL induced extracellular ROS production, intracellular ROS accumulation and cytosolic alkalisation in the mpk9, mpk12 and mpk9 mpk12 mutants. YEL induced [Ca(2+) ]cyt oscillations in both wild type and mpk9 mpk12 mutant. These results suggest that MPK9 and MPK12 function redundantly downstream of extracellular ROS production, intracellular ROS accumulation, cytosolic alkalisation and [Ca(2+) ]cyt oscillation in YEL-induced stomatal closure in Arabidopsis guard cells and are shared with ABA signalling.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Butadienos/farmacologia , Cálcio/metabolismo , Citosol/metabolismo , Flavonoides/farmacologia , Concentração de Íons de Hidrogênio , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/genética , Mutação , Nitrilas/farmacologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/genética , Inibidores de Proteínas Quinases/farmacologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Because of its peculiar geographic location beneath Mont-Blanc, the Chamonix Hospital plays an important role in the management of mountaineering- and skiing-related traumatic injuries. The authors, thanks to the study of 5200 mountain rescue medical reports, set out to explain the different aspects of this activity: epidemiology, specific equipment, care in the field, reception and primary survey, dispatching, common therapeutic attitudes, progress, and results. In the dangerous environment of the high mountains, emphasis is put on the physicians' experience, allowing an early evacuation in the best conditions to the hospital. Diagnosis at the scene of the accident is very basic, and the initial treatment is based on immobilization, analgesia, and sedating. In the case of resuscitation, only the vital maneuvers are performed; these actions are carried on during the short flight and improved in the crash rooms. Finally, different specific pathologies are mentioned, including cold- or heat-related injuries, exhaustion, lightning strikes, and mountain sickness.