unit_5五大植物激素

1、Unit 5 Plant hormones: five major kinds The foolish seedling phenomenon brought on by high levels of gibberellins is characteristic of how hormones function in plants. Three of the five main classes of plant hormones promote and regulate growth, while the other two classes inhibit growth or promote

2、maturation.function : the function of the heartbring on=causeThe drought weather brings on poor harvest of crops in some regions.Characteristic：root physiological characteristics of two rice cultivarsregulate growth promote growthinhibit growth inhibit-inhibition: growth inhibition / photoinhibition

3、Words to remember 1. seedling / si:dli / n. 秧苗，幼苗；树苗秧苗，幼苗；树苗 rice seedling, seedling transplanter 2. gibberellin / ,dibrelins / n.赤霉素赤霉素3. plant hormone 植物激素植物激素4. maturation / ,mtjurein/ n. 成熟成熟 maturation period , post maturation 后熟后熟 The names and activities of all five classes are given in Table

4、 6-1. In general, plant hormones are small molecules that probably act on target cells much the way animal hormones do. Let us survey the growth promoters and growth inhibitors separately then see how they interact to regulate a plants life cycle.much the way :The boy tried to act much the way his f

5、ather did.Inhibitor: bacteria inhibitor 抑菌剂抑菌剂 interact :All things are interrelated and interact on each other. 5. molecule / mlikjul / n.分子；微粒分子；微粒 molecular biology 分子生物学分子生物学6. target cell: 细胞细胞 靶细胞靶细胞7. growth promoter 生长促进剂生长促进剂8. growth inhibitor 生长抑制剂生长抑制剂Words to remember Hormones that prom

6、ote growthGibberellins Gibberellins are a good example of the widespread of particular plant hormones. They are made in a variety of organs, such as young leaves, embryos, and roots, and move passively throughout the plant.A variety of :This degrading process is continually and influenced by a varie

7、ty of factors.passively : People do not merely passively respond to theworld. 9. organ / :n / n.器官器官 organ culture，器官培养，器官培养10. leaf n. 叶子叶子 leaf sheath 叶鞘叶鞘11. embryo / embriu / n.胚胎；胚芽胚胎；胚芽 12. root / ru:t / n. 根；根源根；根源 v. 生根生根 root hair 根毛，根毛，lateral root侧根侧根 Words to remember Gibberellins are pr

8、imarily involved in regulating plant height. Too little gibberellin results in dwarf plants, but too much results in long, pale “foolish” stems. Gibberellins also play important roles in bolting (sudden stem lengthening) in plants such as cabbage and in inducing the seeds of rice, barley, and other

9、grasses to germinate.involved in: Substances involved in the synthesis of amino acidsresults in ： A rise in the temperature of the gas results in its expansion. 13. plant height 株高株高14. stem / stem / n. 干；茎秆干；茎秆 root-stem-leaf-seed15. cabbage / kbid / n.甘蓝甘蓝, 卷心菜卷心菜16. germinate / d:mineit / v. 发芽；生

10、长发芽；生长 germination percentage发芽率发芽率17. rice / rais / n. 稻；米饭稻；米饭18. barley / b:li / n. 大麦大麦19. grasses n. 稻科植物类；禾本种稻科植物类；禾本种 Words to remember CKTreat with gibberellin CK Auxins Like gibberellins, auxins generally promote growth. The name, in fact, comes from the Greek auxein, meaning “to increase,

11、or augment”. Auxins have an even broader set of activities than gibberellins; and instead of being produced in various tissues and travelling up and down through the vascular system, most auxins are made in shoot apical meristems and developing leaves and diffuse from the site of production downward

12、 toward the roots.developing leaves: Auxins are produced mainly by young developing leaves on actively growing shoots. 20. auxin / :ksin / n. 生长素生长素21. tissue / tiju / n. 组织组织22. vascular system 维管系统维管系统 vascular bundle 维管束维管束23. shoot apical meristem 顶端分生组织顶端分生组织 meristem/ meristem / n. 分生组织分生组织 se

13、condary meristem 次生分生组织次生分生组织 Words to remember Auxins promote growth by triggering enzymes that loosen the tightly woven fibers in cell walls, allowing the cell to expand from within. This action leads to the elongation of cells in stems, leaves, and the wall of the ovary.from within :Dreams come f

14、rom within, not from the outside. sunlightSide toward sunlightSide behind sunlight24. enzyme enzaim n.酶酶25. cell wall 细胞壁，胞壁细胞壁，胞壁 cell membrane 细胞膜，细胞膜，cell nucleus 细胞核细胞核26. elongation ,i:lein n. 延长；伸长，延长；伸长， 拔节拔节 elongation elongate 26. ovary uvri n. 子房子房, 卵巢卵巢 Words to remember Auxins also act i

15、n other ways to prevent leaves, fruits, or flowers from falling off prematurely and to inhibit growth in lateral buds and roots in favor of growth at the apical meristem.in favor of : He will testify in favor of the defendant. We are all in favor of an extension of the next term. 27. fruit fru:t n.

16、果实果实28. flower flau n. 花；开花植物花；开花植物29. prematurely ,pri:mtjuli adv. 过早地；早熟地过早地；早熟地 the child was born prematurely. 30. lateral bud 植植 侧芽侧芽 Words to remember In high concentrations, auxins can cause uncontrolled growth and plant death. Garden stores sell the synthetic auxin 2,4-D, which causes the le

17、aves and stems of broad-leaved plants like dandelions to droop and curl within hours. Within days the chlorophyll degrades and the plant dries out and dies.Degrade: This herbicide degrades in moist soil. 31. high concentration 高浓度，高强度高浓度，高强度32. broad-leaved plant 阔叶植物阔叶植物33. chlorophyll klrfil n.叶绿素

18、叶绿素 chlorophyll tissure 叶绿组织叶绿组织 Words to remember During the Vietnam War, the U.S. government sprayed millions of acres with Agent Orange, a mixture containing a chemical related to auxins, to kill forests and expose enemy soldiers and equipment. These plant- killing substances appear to induce suc

19、h rapid cell division and tissue proliferation that the phloem becomes liferation: Pine pollen influences on cell proliferation by improving cell growth. 34. cell division 细胞分裂细胞分裂 cell-division cycle细胞周期细胞周期35. tissue proliferation组织增生组织增生, 组织增殖组织增殖36. phloem fluem n.韧皮部韧皮部 primary phloe

20、m初生韧皮部初生韧皮部 secondary phloem次生韧皮部次生韧皮部 Words to remember Unfortunately, Agent orange is contaminated with dioxin, a compound that many suspect is highly toxic to people. Newer herbicides, such as glyphosate, kill all green plants but are much safer and rapidly degrade completely to harmless compound

21、s.contaminated with : Cereal grains growing in the field are contaminated with a large number of fungus. toxic to : Many microorganisms synthesize and excrete compounds which are selectively toxic to other microorganisms. 37. herbicide / h:bisaid / n. 除草剂除草剂 pestcide 杀虫剂杀虫剂 fungicide 杀真菌剂杀真菌剂38. deg

22、rade / direid / v.降解降解 degradedegradation biological degradation 生物降解生物降解 Words to remember Cytokinins Members of this third class of growth-promoting plant hormones generally stimulate cell division, including cytokininis.stimulate : Applications of gibberellic acid stimulate photosynthesis. Cytoki

23、nins move through the plant less readily than auxins or gibberellins and appear to move in opposition to auxins-from root upward to shoot, not shoot downward to root. Also unlike auxins, cytokinins promote the growth of lateral buds, not shoot tips. Like most plant hormones, cytokinins also have oth

24、er effects, including the prevention of leaf aging, or senescence.less readily: Bromination takes place less readily.in opposition to : Truth stands in opposition to falsehood. 39. cytokinin ,saitukainn n. 细胞分裂素细胞分裂素40. senescence sinesns /n. 衰老衰老 senescence phase 衰老期衰老期 cell senescence 细胞衰老细胞衰老 pla

25、nt senescence 植株的衰老植株的衰老Words to remember Table 6-1 Plant HormonesHormoneTransportAction GibberellinsUpward and downward in vascular system Promote growth; promote stem lengthening in dwarf and rosette plants and seed germination in grasses; involved in flowering and fertilization; involved in growt

26、h of new leaves, young branches and fruitsAuxinsFrom tip of shoot downward in vascular systemPromote growth; augment growth by cell elongation; inhibit growth of lateral buds; foster growth of ovary wall; prevent leaf and fruit drop; orient root and shoot growth Cytokinins From root upward in vascul

27、ar system Promote growth; stimulate cell division; kindle growth in lateral buds; block leaf senescence CKcytokininisstimulate cell divisionHORMONES THAT INHIBIT GROWTH If plants had only gibberellins, auxins, and cytokinins, they would grow constantly. Sometimes, however, it is more advantageous fo

28、r the plant to stop growing-to close its stomata, decrease the level of photosynthesis, drop aging leaves, or become dormant. 41. stomata / stumt / n. 气孔气孔 stomata density气孔密度气孔密度42. photosynthesis / ,futsinsis / n. 光合作用光合作用 photosynthetic product光合产物光合产物43. dormant / d:mnt / adj. 休眠的；静止的；休眠的；静止的； d

29、ormant period潜伏期；休眠期潜伏期；休眠期 dormant bud 休眠芽；潜伏芽休眠芽；潜伏芽 Words to remember Abscisic Acid Abscisic acid ( ABA ) counteracts the growth hormones, apparently by indirectly blocking protein synthesis and new growth. ABA moves only short distances from its site of production. For decades, scientists believ

30、ed that ABAs main role was to accelerate the dropping of leaves and fruit (abscission).Counteract: This drug should counteract the poison. Now, however, they think that the main role of ABA is to induce and maintain metabolic slowdown, or dormancy, especially in buds, and the closing of a leafs gas

31、exchange pores (stomata) to prevent excess water loss.Metabolic: Metabolic activity quickly develops in the cells of the embryo. Dormancy: seed dormancy / bud dormancy44. abscisic acid 脱落酸脱落酸45. protein / pruti:n / n. 蛋白质蛋白质 convert amino acids to protein46. metabolic / ,metblik / adj. 新陈代谢的新陈代谢的 metabolic disorder代谢失调代谢失调 metabolism /mitblizm / n.新陈代谢新陈代谢47. dormancy / d:mnsi / n. 休眠休眠 Words to remember Ethylene The fifth major plant hormone is a small, simple molecule that exists a