解析植物冷信号转导途径: 植物如何感知低温

doi:10.11983/CBB18039

摘要/Abstract

摘要： 低温胁迫(冷害和冻害)严重影响植物的生长发育和地理分布, 是制约作物产量和品质的主要因素之一。在自然界, 植物通过感知低温信号并启动一系列响应机制来抵御冷冻伤害。MAP蛋白激酶家族在植物响应逆境胁迫信号过程中发挥重要作用, 但其是否参与冷冻胁迫信号传递仍不清楚。最近, 朱健康、杨淑华和种康研究团队先后报道了拟南芥(Arabidopsis thaliana)和水稻(Oryza sativa)通过MAPK级联反应途径参与冷冻胁迫应答反应, 通过磷酸化ICE1来调控其稳定性, 并阐明了ICE1提高植物抗冷冻能力的分子机制。他们的研究完善了ICE1介导的低温应答网络, 是植物低温应答研究领域的重要突破, 并为未来的作物分子设计育种提供了强有力的理论依据。

关键词: 低温应答, 磷酸化, MAPK级联反应, ICE1, OsTPP1

Abstract: Cold (chilling or freezing) stress affects the growth and geographical distribution of plants, and it is one of the main factors that restricts crop yield and quality. Plants respond to cold signals by activating a series of effectors to adapt to cold stress. MAP protein kinase family plays a crucial role in plant response to environmental stresses, but it remains unclear whether they are directly involved in perception, transduction or/and networks in cold signaling. Recently, three research groups in China highlight the important role of MAP kinase in cold signaling transduction in Arabidopsis thaliana and rice, respectively. Low temperature activates MPK kinase that phosphorylates the ICE1 protein. Stability of ICE1 is controlled by MAP kinase mediated ICE phosphorylation, thus regulating freezing and chilling tolerance in plants. Their studies have advanced our understanding of the ICE1-mediated network of plant cold responses, which is an important breakthrough in the field. The outcome of these studies would provide a powerful theoretical basis for future molecular design breeding in crops.

Key words: cold response, phosphorylation, MAPK cascades, ICE1, OsTPP1

段志坤, 秦晓惠, 朱晓红, 宋纯鹏. 解析植物冷信号转导途径: 植物如何感知低温. 植物学报, 2018, 53(2): 149-153.

Duan Zhikun, Qin Xiaohui, Zhu Xiaohong, Song Chunpeng. Making Sense of Cold Signaling: ICE is Cold or not Cold?. Chinese Bulletin of Botany, 2018, 53(2): 149-153.

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链接本文: https://www.chinbullbotany.com/CN/10.11983/CBB18039

https://www.chinbullbotany.com/CN/Y2018/V53/I2/149

图/表 1

图1 MAP激酶级联反应调控拟南芥和水稻低温应答的工作模型低温刺激诱导细胞质钙信号的变化。在拟南芥中, 作为钙调蛋白的类受体激酶CRLK1和CRLK2被快速激活, 启动MEKK1-MKK2- MPK4信号级联, 抑制了MPK3/6活性, 正调控植物抗冷反应。另一个信号通路MKK4/5-MPK3/6同样被冷胁迫快速诱导, 在MKK5存在的情况下, MPK3/6被激活, 磷酸化ICE1, 促进其降解, CBFs转录水平下降, 负调控植物抗冷反应。MPK3/6诱导的ICE1降解, 与HOS1泛素化降解过程无关。同时, OST1也可磷酸化ICE1, 但其磷酸化作用抑制HOS1对ICE1的泛素化降解, 从而起到正调控作用。在水稻中, 冷胁迫诱导OsMAPK3激活, 而后磷酸化OsICE1。同时, OsMAPK3抑制OsHOS1和OsICE1的结合, 进而抑制OsICE1的降解, 维持了OsICE1的稳定。被磷酸化的OsICE1激活OsTPP1的转录, 促进海藻糖的累积, 增强水稻耐冷能力。(箭头代表激活, 短横线代表抑制, 虚线代表机制尚不清楚。红色线代表拟南芥内信号通路, 黑色线代表水稻内信号通路)

Figure 1 A proposed working model shows the roles of MAP kinase cascades during the cold response in Arabidopsis and riceLow temperature induces changes in cytoplasmic calcium signaling. In Arabidopsis, calcium/calmodulin regulated receptor-like kinase 1 and 2 (CRLK1 and CRLK2) are activated by cold signal, and then initiate MEKK1-MKK2-MPK4 cascade, which suppresses cold-induced activation of MPK3/6, thus positively regulating cold tolerance. MKK4/5-MPK3/6 cascades can also be rapidly activated in cold stress in parallel with MEKK1-MKK2-MPK4. Constitutively activated MPK3/6 by MKK5 phosphorylate ICE1 to promote degradation of ICE1, which decreases the transcriptional activity of CBFs, thus negatively regulating cold to- lerance in Arabidopsis. OST1 also phosphorylates and affects the stability of ICE1, and positively regulate cold tolerance. In rice, cold signal induces the activation of OsMAPK3 that phosphorylates the OsICE1 and inhibits OsICE1 degradation by interrupting the interaction of OsHOS1 and OsICE1 to maintain the stability of OsICE1. Phosphorylated OsICE1 activates the transcription of OsTPP1 to promote the accumulation of trehalose, and enhances the cold tolerance of rice. (Arrows represent activation, and bars represent inhibition, dotted lines represent unknown mechanisms. Red lines represent signal pathways in Arabidopsis, and black lines represent signal pathways in rice)

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