title: The Receptor-Like Kinase SIT1 Mediates Salt Sensitivity by Activating MAPK3/6 and Regulating Ethylene Homeostasis in Rice.
abstract: High salinity causes growth inhibition and shoot bleaching in plants that do not tolerate high salt (glycophytes), including most crops. The molecules affected directly by salt and linking the extracellular stimulus to intracellular responses remain largely unknown. Here, we demonstrate that rice (Oryza sativa) Salt Intolerance 1 (SIT1), a lectin receptor-like kinase expressed mainly in root epidermal cells, mediates salt sensitivity. NaCl rapidly activates SIT1, and in the presence of salt, as SIT1 kinase activity increased, plant survival decreased. Rice MPK3 and MPK6 function as the downstream effectors of SIT1. SIT1 phosphorylates MPK3 and 6, and their activation by salt requires SIT1. SIT1 mediates ethylene production and salt-induced ethylene signaling. SIT1 promotes accumulation of reactive oxygen species (ROS), leading to growth inhibition and plant death under salt stress, which occurred in an MPK3/6- and ethylene signaling-dependent manner in Arabidopsis thaliana. Our findings demonstrate the existence of a SIT1-MPK3/6 cascade that mediates salt sensitivity by affecting ROS and ethylene homeostasis and signaling. These results provide important information for engineering salt-tolerant crops.
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Chen-Hui
authors.initials: CH
authors.lastname: Li
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Geng
authors.initials: G
authors.lastname: Wang
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Ji-Long
authors.initials: JL
authors.lastname: Zhao
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Li-Qing
authors.initials: LQ
authors.lastname: Zhang
authors.affiliation: Hebei Entry-Exit Inspection and Quarantine Bureau of China, Shijiazhuang, Hebei 050028, P.R. China.
authors.forename: Lian-Feng
authors.initials: LF
authors.lastname: Ai
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China.
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Han
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Da-Ye
authors.initials: DY
authors.lastname: Sun
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China.
authors.forename: Sheng-Wei
authors.initials: SW
authors.lastname: Zhang
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Hebei 050024, P.R. China Key Laboratory of Molecular and Cellular Biology of Ministry of Education, College of Life Science, Hebei Normal University, Hebei 050024, P.R. China Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, P.R. China yingsun@mail.hebtu.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun