Li Chen-Hui, Wang Geng, Zhao Ji-Long, Zhang Li-Qing, Ai Lian-Feng, Han Yong-Feng, Sun Da-Ye, Zhang Sheng-Wei, Sun Ying
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.
Hebei Entry-Exit Inspection and Quarantine Bureau of China, Shijiazhuang, Hebei 050028, P.R. China.
Plant Cell. 2014 Jun;26(6):2538-2553. doi: 10.1105/tpc.114.125187. Epub 2014 Jun 6.
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.
高盐度会导致不耐高盐的植物（甜土植物），包括大多数作物，生长受抑制和地上部白化。直接受盐影响并将细胞外刺激与细胞内反应联系起来的分子在很大程度上仍不清楚。在这里，我们证明水稻（Oryza sativa）耐盐性1（SIT1），一种主要在根表皮细胞中表达的凝集素受体样激酶，介导盐敏感性。NaCl迅速激活SIT1，在有盐的情况下，随着SIT1激酶活性增加，植物存活率降低。水稻MPK3和MPK6作为SIT1的下游效应物发挥作用。SIT1使MPK3和6磷酸化，它们被盐激活需要SIT1。SIT1介导乙烯产生和盐诱导的乙烯信号传导。SIT1促进活性氧（ROS）积累，导致盐胁迫下生长受抑制和植物死亡，这在拟南芥中以MPK3/6和乙烯信号依赖的方式发生。我们的研究结果证明存在一个SIT1-MPK3/6级联反应，该级联反应通过影响ROS和乙烯稳态及信号传导来介导盐敏感性。这些结果为培育耐盐作物提供了重要信息。
