Stress Signaling in Plants 贾文锁贾文锁 中国农业大学中国农业大学一 “感知感知”和和“反应反应” 生物生存和发展的基础生物生存和发展的基础 敏感植物敏感植物 一般植物一般植物Rain,Wind, and Touch-Induced Expression of Calmodulin and Calmodulin-Related Genes in ArabidopsisCell 60,357-364,1990二“刺激刺激/逆境逆境”“反应反应/应答应答”1. 1.形态、解剖形态、解剖Cluster Roots2. 2.整体生理整体生理生命周期短命菊3.细胞生理及生化(1) 解毒机制(2)自由基清除(3)区隔化机制(4)代谢调控(5)渗透调节(6)保水机制(7)结构避损机制(8)修复机制渗透调节渗透调节脯氨酸脯氨酸甜菜碱甜菜碱山梨醇山梨醇海藻糖海藻糖保护酶系统与自由基清楚剂保护酶系统与自由基清楚剂游离的带有不成对电子的分子、原子或离子游离的带有不成对电子的分子、原子或离子区隔化机制区隔化机制结构避损机制结构避损机制功能蛋白功能蛋白 代谢调控蛋白 （渗透调控系统，保护酶）Lea 蛋白（Late-Embryogenesis-Abundant Protein）通道蛋白：离子通道，水通道热击蛋白：亲水，保护酶活损伤修复蛋白调节蛋白调节蛋白信号蛋白转录因子基因功能蛋白基因调节蛋白基因应答反应与伤害反应三 信号系统与信号组分 Cellular Singling System ?细胞信号系统细胞信号系统1 Receptor /Sensor2. Second Messenger3. Protein Kinase 4. Protein Phosphatase5. G-protein6. Transcription Factor 7. Ubiquitination 8. Methylation Signal Components(1) Receptor /Sensor?Receptor tyrosine kinase 细胞内受体Examples of Phytohormone Recepor and Signal TransductionABA Receptor BRI1 is a membrane-associated receptor that cycles between the plasma membrane and endosomal compartments. The extracellular leucine-rich repeat domain binds brassinosteroids and transduces the signal through an intracellular kinase domain. GTG1 and GTG2 are GPCR-type G proteins that bind abscisic acid. They have inherent GTPase activity but also interact with the only canonical G subunit in Arabidopsis. PYR1/RCAR1 is a soluble ABA receptor that represses PP2C phosphatases in the presence of ABA. The cytokinin receptors CRE1, AHK2 and AHK3 are plasma-membrane-associated and perceive cytokinin through their extracellular domains. Cytokinin binding triggers a phosphorylation cascade that is ultimately transmitted to response regulators in the nucleus. Like the cytokinin receptors, the known ethylene receptors are two-component regulators. All five receptors are active in the endoplasmic reticulum and transmit their signal through a common downstream component called CTR1. TIR1 and COI1 are F-box proteins that are integral components of SCF-type E3 ligases and recognize the plant hormones auxin and jasmonic acid respectively. GID1 is a nuclear-localized receptor for gibberellins. Gibberellin binding toGID1 results in the enhanced degradation DELLA proteins 自由基信号转导(3) Reversible Protein Phosphorylaton (4) Transcription Factors 泛素泛素(ubiquitin)(ubiquitin)是一种存在于大多数真核细胞中的小蛋白。它的主要功能是标记需要分解掉的蛋白质，使其被水解。当附有泛素的蛋白质移动到桶状的蛋白酶的时候，蛋白酶就会将该蛋白质水解。也可能被转移到细胞或细胞外的特定部位，也有可能导致靶蛋白的功能发生变化。泛素76个氨基酸组成，分子量大约8.5 KDUbiquitination 四细胞逆境信息传递细胞逆境信息传递 举例介绍举例介绍盐胁迫和营养胁迫离子通道的调节Figure 12. Freezing and Drought Tolerance of the 35S:DREB1Ab and 35S:DREB1Ac Transgenic Plants.Control, 3-week-old plants growing under normal conditions; freezing stress, plants exposed to a temperature of -6C for 2 days and returned to 22C for 5 days; drought stress, water withheld from plants for 2 weeks. Percentages of surviving plants and numbers of surviving plants per total number of tested plants are indicated under the photographs. wt, wild type. History of Abscisic Acid (ABA) In 1963, abscisic acid was first identified and characterized by Frederick Addicott and his associates. They were studying compounds responsible for the abscission of fruits (cotton). Two compounds were isolated and called abscisin I and abscisin II. Abscisin II is presently called abscisic acid (ABA)(Addicot, 1963). Two other groups at about the same time discovered the same compound. One group headed by Philip Wareing was studying bud dormancy in woody plants. The other group led by Van Steveninck was studying abscission of flowers and fruits from lupine. Plant physiologists agreed to call the compound abscisic acid (Salisbury and Ross, 1992). Signaling From Water Stress Sensing to ABA Accumulation 五五 系统逆境信息传递系统逆境信息传递Systematic Signaling in Plantsor long-distance signaling, or intercellular signalingRoot To Shoot Signaling Under Water Deficit Condition pH SignalingImage Image 2. 2. Psedu Psedu Color Color Ratio-images Ratio-images of of pH indicator BCECF in sunflower sunflower stem and leaf vascular systemstem and leaf vascular system pH indicator BCECF was loaded into the vascular system of an individual sunflower plant and images were acquired as described in Material and Method. A, vascular system at stem base; B, vascular system at midrib of leaf blade. Image Image 3. 3. Psedu Psedu Color Color Ratio-images Ratio-images Showing Showing the the Effect Effect of of transpiration transpiration rate rate on on leaf leaf apoplastic apoplastic pH pH of of Commelina Commelina communis L. communis L. pH indicator NERF was first loaded into intact plant through root system, then the plants were allowed to transpire for 1 h under either 35% or 85% humidity, following which fluorescence images were acquired as described in Material and Method . A and B, transpiration at 35% humidity; C and D, transpiration at 85 % humidity.Image Image 3. 3. Psedu Psedu Color Color Ratio-images Ratio-images Showing Showing the the Effect Effect of of transpiration transpiration rate on leaf apoplastic pH of Commelina communis L. rate on leaf apoplastic pH of Commelina communis L. pH indicator NERF was first loaded into intact plant through root system, then the plants were allowed to transpire for 1 h under either 35% or 85% humidity, following which fluorescence images were acquired as described in Material and Method . A and B, transpiration at 35% humidity; C and D, transpiration at 85 % humidity.干旱条件下ABA可以作为长距离传递信号使植物产生系统抗逆性Systematic Signaling of Large Molecular SignalsFig. 3. New model for the photoperiod response in plants. (A) The picture on the left represents the currently accepted model forArabidopsis, in which light-activated CO overcomes the temperature-dependent inhibition from FLC and induces the expression of FT in the phloem companion cells. FT is moved to the phloem and channelled to the apical meristem where it binds to FD and the complex is recruited into the nucleus. FTFD binds to the promoter of SOC1 and other meristematic floral integrators, changing the vegetative developmental programme to the ABC programme, eventually producing flowers. (B) The model proposed here includes that depicted in A, but also recruits similar photoperiodic mechanisms to regulate other developmental programmes and basic physiological processes. Yellow arrows represent external signals: day/night transition; circadian clock; light quality; and a metabolic signal represented by a fertilizer bottle. Black arrows indicate some of the outputs of the photoperiodic response.一些值得深入思考的问题一些值得深入思考的问题“逆境应答反应逆境应答反应” = “抗逆反应抗逆反应”吗吗?“逆境应答基因逆境应答基因” = “抗逆基因抗逆基因”吗吗? “应答基因应答基因”中真的存在关键的基因吗中真的存在关键的基因吗? “关键的抗逆基因关键的抗逆基因”一定是一定是”逆境应答基因逆境应答基因”吗吗? “逆境应答反应逆境应答反应”的本质是什么的本质是什么? 是为抗逆而是为抗逆而独立存在的吗独立存在的吗?功能解析3 刚才的发言，如刚才的发言，如有不当之处请多指有不当之处请多指正。谢谢大家！正。谢谢大家！92