6植物生理学讲义.pptx

第第 五五 章章植物体内有机物的代谢植物体内有机物的代谢本章重点和难点：v一、植物体内有机物质的次级代谢；v二、植物次级产物的合成途径。第一节第一节 各类有机物代谢的相互关系各类有机物代谢的相互关系v蔗糖、淀粉等有机物来源于光合作用，通过呼吸作用分解产蔗糖、淀粉等有机物来源于光合作用，通过呼吸作用分解产生各种中间产物。生各种中间产物。vC3循环、循环、EMP、TCA和和PPP筑成了有机物代谢的主干筑成了有机物代谢的主干。v糖和脂肪、蛋白质、核酸之间都可以相互转变。糖和脂肪、蛋白质、核酸之间都可以相互转变。v丙酮酸、乙酰丙酮酸、乙酰COA、-酮戊二酸、草酰乙酸酮戊二酸、草酰乙酸等中间产物起着等中间产物起着枢纽作用。枢纽作用。Plant SecondaryMetabolismvPlant metabolic pathways are linkedvThese linkages include several key carbon-based primary metabolites(初级代谢物)vAs plants evolved,they found new(secondary)ways to use metabolitesvRandom mutations lead to a variety of specialized plant secondary compounds葡萄糖葡萄糖多糖多糖淀粉、纤维素淀粉、纤维素半纤维素半纤维素戊糖戊糖(Ru5P)核苷酸核苷酸核酸核酸DHAPPGAldPEP丙酮酸丙酮酸乙酰乙酰C CO OA A-酮戊二酸酮戊二酸C3途径途径CO2草酰乙酸草酰乙酸TCA丙二酰C CO OA A甘油甘油+脂肪酸脂肪酸脂肪脂肪酚类、萜类酚类、萜类化合物化合物丙氨酸等丙氨酸等酒精酒精乳酸乳酸天冬氨酸族天冬氨酸族烟碱烟碱AMP、GMP谷氨酸族谷氨酸族蛋白质蛋白质卟啉(chl,Cyt)PPP第二节第二节 植物体内的次级产物植物体内的次级产物v次级产物：次级产物：是植物体内由糖类等有机物代谢衍生糖类等有机物代谢衍生而来的物质。贮存在液泡或细胞壁中，是代谢的中产物，不再参与代谢。v次级产物具有重要作用：次级产物具有重要作用：是植物生命活动所必需的，如IAA、GA；叶绿素和类葫萝卜素及花色素；木质素等，是植物组织色、香、味的主要构成成分，是药业或工业的重要原料。v植物的次级产物可分植物的次级产物可分3类：类：酚类、萜类、含氮次级化合物酚类、萜类、含氮次级化合物v萜类的种类：萜类是以异戊二烯(isoprene)为单位组成的，按其数目，可分为:单萜(monoterpene)、倍半萜(sesquiterpene)、双萜(diterpene)、三萜(triterpene)、四萜(tetraterpene)、多萜(polyterpene)。CH3 头 CH2=C CH=CH2 尾一、一、萜萜 类类 terpeneTerpenoids:The largest groupvFormed from 5-C subunits(isoprene)synthesizedfrom G-3-P,pyruvate,and acetyl-CoAvCompounds have from 10 to 40 carbonsvSome terpenoids have functions in growth anddevelopmentv Plant hormones(gibberellins,abscisic acid)v Accessory pigments in photosynthesisvMost terpenoids act as herbivory deterrents andare a prime example of a“biochemical arms race”Monoterpenes(C-10)vPyrethroid insecticides拟除虫菊脂vConifer resins松脂vPlant-plant defensive Communication防御沟通 Deter pest Attract pest predatorsvEssential oils（Essential oils are often stored in surface glands表面腺细胞）Sesquiterpenes(C-15)vHerbivory deterrents威慑草食动物(generalized)vBitternessvExamples include sagebrush山艾树 and sunflower向日葵Diterpenes(C-20)vToxins and irritants毒与刺激(generalized)vResins from some trees to seal herbivore induced wounds松脂封闭取食伤口vHuman use has adapted these compounds to anti-cancer drugs(Taxol紫杉醇 from Pacific yew紫杉)Tri-terpenes(C-30)vMore specialized toxinsvSteroid in structure结构类固醇vExamples Cardenolides vertebrate heart toxins脊椎动物心脏毒素 Saponins 皂角苷 detergent like structurev植物体内重要的萜类物质：植物体内重要的萜类物质：挥发油：是单萜和倍半萜，樟树茎、柑橘果皮、薄荷植株等 棉 酚：倍半萜，是重要的抗虫侵袭、抗真菌和细菌的物质 固 醇：三萜的衍生物，质膜成分，植物蜕皮激素的成分 类胡萝卜素：四萜衍生物，有叶黄素、胡萝卜素番茄红素等，橡 胶：多萜化合物一、一、萜萜 类类 terpene二、酚二、酚 类类phenolv种类：种类：按芳香族环上带有的碳原子数可分为按芳香族环上带有的碳原子数可分为 简单酚类、木质素、类黄酮类、鞣质类和其它简单酚类、木质素、类黄酮类、鞣质类和其它酚类酚类v主要的酚类化合物有：主要的酚类化合物有：简单酚类：简单酚类：桂皮酸、咖啡酸、香豆素、水扬酸桂皮酸、咖啡酸、香豆素、水扬酸 木质素：木质素：没食子酸、木质素、没食子酸、木质素、类黄酮类：类黄酮类：花色素苷、黄酮、黄酮醇、异黄酮花色素苷、黄酮、黄酮醇、异黄酮 鞣质类鞣质类：缩合鞣质和可水解鞣质：缩合鞣质和可水解鞣质Phenolic compoundsvCommon element is a phenolic groupvDerived from amino acids,principally phenylalanine（苯丙氨酸）Examples of phenolic compounds and their rolesvPhenylpropanoids（苯丙酸类化合物），具有苯环-C3的基本骨架。vAllelopathic compounds inhibit plant growth（A为咖啡酸、阿魏酸）Examples of phenolic compoundsand their rolesvFuranocoumarins 呋喃香豆素类(celery芹菜,parsnip欧洲防风草,and parsley欧芹)vToxicity to insect herbivores（草食昆虫毒素）vUV-activated toxins：UVA（320-400nm）激发为高能电子态，插入DNA中，与胞嘧啶和胸腺嘧啶结合，阻断DNA转录和修复，导致细胞死亡。Examples of phenolic compoundsand their rolesvBenzoic acid derivatives（安息香酸派生物）vSystemic resistance to pathogens（病原物系统抗性）Plant“immune systems”vPlant-wide response to a local infectionvMay involve both toxic compounds like oxygen radicalsvCan produce a memory responsePlant“immune systems”vPhytoalexins（植物抗毒素）are a primary player in plant immune responsevPhytoalexins can be antimicrobial terpenoids or phenolics（抗菌的萜或酚类）vSynthesized in response to infection or attackJasmonic acid Stress anddefense hormonevProduced in response to a signal transduction pathwayvInduces synthesis of other defensive compoundsvActivates responses at the gene levelExamples of phenolic compoundsand their rolesvLignin木质素 Reinforcing molecule(esp.in woody tissue)组成物质 Decreases palatabilityvTannins丹宁 Flavor deterrent威慑味道，如涩味 Tea,blackberry,grape,apple Mode of action is via protein binding蛋白鞣质结合Examples of phenolic compoundsand their rolesvFlavonoidsv Anthocyanins（花青素）:Pigmentation(pollinator attractant)v Flavones and Flavonols（黄酮和黄酮醇）:UV protection and beevAttractant（引诱剂）：(nectar guides花蜜引导)v Isoflavones（异黄酮）:Antimicrobial（抗菌）,antiestrogenic（抗雌激素）三、含氮次级化合物三、含氮次级化合物l生物碱生物碱(alkaloid)：核酸的组分，亦是维生素：核酸的组分，亦是维生素B1、叶酸和生物素的组叶酸和生物素的组 分，分，它对动物有毒，可起防它对动物有毒，可起防御敌害作用；是重要药物的御敌害作用；是重要药物的 有效成分，如奎宁、有效成分，如奎宁、吗啡、利血平、阿托品等。吗啡、利血平、阿托品等。l含氰苷含氰苷(cyanogenic glycoside)：豆类、禾谷类：豆类、禾谷类和玫瑰中较多，本无毒，但释放和玫瑰中较多，本无毒，但释放HCN。l芥子油苷芥子油苷(mustard oil glycoside)：十字花科，：十字花科，本无毒，但水解后产生有毒物质。本无毒，但水解后产生有毒物质。l非蛋白氨基酸非蛋白氨基酸(nonprotein amino acid)：不构成：不构成蛋白质的氨基酸，有毒性，有的阻止蛋白质的氨基酸，有毒性，有的阻止 蛋白氨基酸蛋白氨基酸的合成或吸收。的合成或吸收。Nitrogen-Containing Compounds:vOnly chemical similarity is the presence of nitrogen somewhere in the moleculevWell studied because of their toxicity to animals and their medicinal valuevPerhaps the most easily-recognizable group of secondary compounds in plantsExamples of N-containingcompounds and their rolesvAlkaloidsv A large group of compounds found in 20%ofall plant speciesv All contain a heterocyclic ring杂环(i.e.,a ring formed from carbons and one nitrogen)v Best known for their pharmacological effect on animals(动物药理学的效应)Examples of alkaloidsExamples of N-containingcompounds and their rolesvCyanogenic glycosides含氰苷，存在与叶表皮的液泡中v A large group of compounds found in thousands of plant speciesv Stored in leaves(cherry樱桃,Johnson grass),seeds(apple,peach),or roots(cassava木薯)v Enzymatic release of cyanide gas following herbivoryExamples of N-containingcompounds and their rolesvGlucosinolates(mustard oil glycosides)芥子油苷芥子油苷：十字花科，本无毒，但水解后产生有毒物质。十字花科，本无毒，但水解后产生有毒物质。v Principally found in plants from the Brassicaceaev Enzymatic release following herbivoryv Volatile defensive compounds 挥发性防御物(toxins,deterrents)v Can also serve as attractants引诱剂Examples of N-containingcompounds and their rolesl非蛋白氨基酸非蛋白氨基酸：不构成蛋白质的氨基酸，有：不构成蛋白质的氨基酸，有毒性，有的阻止毒性，有的阻止 蛋白氨基酸的合成或吸收。蛋白氨基酸的合成或吸收。vNon-protein amino acidsv Interfere with herbivore protein synthesisv Replace normal amino acids to create nonfunctional proteins