11Physiologyofplantmaturationandsenescence

1、chapter 11 physiology of plant maturation and senescence11.1 development and maturation of seeds11.2 growth and maturation of fruits11.3 physiology of plant dormancy11.4 physiology of plant senescence11.5 physiology of plant abscission11.1 development and maturation of seeds11.1.1 development of see

2、dssperm+eggzygoteembryosperm+2 polar nucleiendospermdoublefertilization表皮原表皮原11.1.1.1 development of embryo (embryogenesis)11.1.1.2 development of endospermoryza sativahopea hainanensislycopersicon esculentum 11.1.1.3 gene expression during seed development11.1.2 accumulation of storage reserves dur

3、ing seed development11.1.2.1 starch and other carbohydrates mannan甘露聚糖甘露聚糖carbohydrates: solubleunsolubeenzymes: starch phosphorylase, q enzyme11.1.2.2 proteins3d5d7d9d11d 13d15d20d25d yan et al, 2006, seed science & technology7.5.3 developmental and physiological effects aba promotes the accumu

4、lation of seed storage proteins during embryogenesisaba levels in seeds peak during embryogenesisseed dormancy is controlled by aba/ga aba inhibits precocious germination and viviparyvivipary: seeds germinate on mother plants11.1.2.3 lipids 油料种子中的脂肪是由糖（葡萄糖、蔗糖、油料种子中的脂肪是由糖（葡萄糖、蔗糖、淀粉）转化而来的。淀粉）转化而来的。 先形

5、成游离脂肪酸，再合成复杂的油脂。因先形成游离脂肪酸，再合成复杂的油脂。因而而酸价酸价（中和（中和1克油脂中游离脂肪酸所需的克油脂中游离脂肪酸所需的koh的毫克数）逐渐降低。的毫克数）逐渐降低。 先形成饱和脂肪酸，再变为不饱和脂肪酸。先形成饱和脂肪酸，再变为不饱和脂肪酸。因而因而碘价碘价（100克油脂所能吸收碘的克数）逐克油脂所能吸收碘的克数）逐渐增加。渐增加。3 characteristics of lipid accumulation11.1.2.4 phytino-po-po-po-po-pp-o-ca, mg.-ca, mg.-ca, mg.-ca, mg.-ca, mg. mg,ca

6、-11.1.3 other physiological changes11.1.3.1 respiration rate11.1.3.2 plant hormones（1）风旱不实：热风和干旱使籽粒灌浆不足，）风旱不实：热风和干旱使籽粒灌浆不足， 并影响种子成分的现象。并影响种子成分的现象。（2）温度：低温有利油脂和不饱和脂肪酸积累）温度：低温有利油脂和不饱和脂肪酸积累（3）营养条件：）营养条件： n：提高淀粉种子蛋白含量：提高淀粉种子蛋白含量 k：提高淀粉种子淀粉含量：提高淀粉种子淀粉含量 k、p：提高油料种子的脂肪含量：提高油料种子的脂肪含量 n：提高油料种子的蛋白含量，但减少脂：提高油料

7、种子的蛋白含量，但减少脂 肪含量肪含量 11.1.4 factors influencing composition and maturation of seeds back11.2 growth and maturation of fruits11.2.1 characteristic of fruit growthgrand period of growths shapesingle sdouble sparthenocarpy(单性结实单性结实):不经受精作用而形成不经受精作用而形成不含有种子的果实。不含有种子的果实。 natural parthenocarpy: mutation, h

8、igh iaa contentstimulated parthenocarpy: temp., day lengthartificial parthenocarpy: iaa and gas无子西瓜之父？无子西瓜之父？11.2.2 physiological and biochemical changes11.2.2.1 respiratory climacteric and ethylene releaserespiratorypeakduring fruit maturationclimacteric fruits: banana, pear, peach, apple, plum, ma

9、ngo, tomato, watermelon, etc.non-climacteric fruits: strawberry, grape, orange, cherry, cucumber, etc.ethylene release 研究表明，在呼吸跃变开始或正要开始时，研究表明，在呼吸跃变开始或正要开始时，果实内乙烯含量明显果实内乙烯含量明显。因此认为乙烯大量。因此认为乙烯大量增增加果皮细胞透性，使果实内部的氧化过程加强，加果皮细胞透性，使果实内部的氧化过程加强，促进果实呼吸作用，加速果实成熟。促进果实呼吸作用，加速果实成熟。 实践中，可通过调节呼吸骤变的来临，以实践中，可通过调节呼吸骤

10、变的来临，以达到推迟或提早果实成熟的目的。如：可降低达到推迟或提早果实成熟的目的。如：可降低温度和温度和o2，提高，提高co2 浓度或充浓度或充n2 来延迟呼吸来延迟呼吸骤变，达到保鲜目的。而反之，提高骤变，达到保鲜目的。而反之，提高t或增加或增加o2 浓度，或施用乙烯，则可刺激骤变来临，催浓度，或施用乙烯，则可刺激骤变来临，催熟果实。熟果实。11.2.2.2 color, fragrant and taste changesduring fruit maturationwhat happens? greenyellow, red, orange chlorophylls, carotenoi

11、ds, anthocyanin artistic apple? release of fragrant gases: volatile substances (脂肪族和芳香族酯类，脂肪族和芳香族酯类， 以及一些特殊的醛类以及一些特殊的醛类) apple: 乙酸丁酯、乙酸乙酯乙酸丁酯、乙酸乙酯 banana: 乙酸戊酯、甲酸甲酯乙酸戊酯、甲酸甲酯 orange: 柠檬醛柠檬醛 color changes: acid: organic acids (malic acid, citric acid) sugars respiration neutralized by k+, ca2+ astring

12、ent: soluble tannin peroxidase insoluble substances sweet: glucose, fructose, sucrose starchsoluble sugars organic acidssugars taste changes: acid and astringentsweet softening of fruit: cw dedradation (insoluble pectinssoluble) starchsoluble sugars 11.2.2.3 plant hormone changesback11.3 physiology

13、of plant dormancydormancy: very slow or stop temporarily biological functionsdormant organs: seed, bud, root11.3.1 reasons and break of seed dormancyseed dormancy: viable, not germinatesuitable conditions seed coat constraint?hard seed: not permeable to water, gasbreak: biological, physical, chemica

14、lendosperm weakening: the hatching-enzyme hypothesis. the final step in the germination control process is the production of an enzyme whose action enables the tip of the radicleto penetrate through the coat. ikuma and thimann (1963). endosperm weakeningis likely to be essential forsome seeds to com

15、plete germination, how this is achieved remains a mystery. derek bewley (1997)lactuca sativalettuce seedikuma and thimann, plant & cell physiol 4:169-185 (1963)halmer, bewley, thorpe, nature 258:716-718 (1975)tao and khan, plant physiol 63:126-128 (1979)reviews: bewley (1997), plant cell 9:1055-

16、1066 and tips 2:464-469endo-b b-mannanase? b b-1,3-glucanase?b b-1,3-glucanase and lettuce endosperm weakeningendosperm rupturedwarf mutant of lettuce seedsd4 after ripening is requiredmatured morphologically, but not physiologicallyafter ripening: physiological changesstratification: wet sand, low

17、temperaturedry storagerespirationenzyme activitiesstorage reserves degradationplant hormone permeability to water and gas embryo development is not finished yetmorphological after ripening existence of inhibitory substancesinhibitory substances:abahcn、ethylene, nh3芥子油、精油芥子油、精油sa、没食子酸、阿魏酸、香豆素、没食子酸、阿魏

18、酸、香豆素柠檬醛、肉桂醛柠檬醛、肉桂醛咖啡碱、古柯碱咖啡碱、古柯碱location of inhibitory substances:pulpseed coatendospermcotyledonsbiological functions of inhibitory substances in the seed coat:seeds in the desert can utilize the inhibitory substances in the seed coat to measure the volume of rain, and determine the germination.11

19、.3.2 regulation of seed dormancybreakelongationj. derek bewleyback11.4 physiology of plant senescence senescence: normal, energy-dependent developmental process, controlled by the plants own genetic program. 11.4.1 plants exhibit various types of senescencemonocarpic（结一次果）（结一次果） senescence: annual,

20、biennial necrosis: death brought about by physical damage, poisons, or other external injury.soybean (glycine max)aerial senescence: herbaceous perennialssequential senescence: ever-green woody perennial, leaves die when they reach a certain ageseasonal leaf senescence: woody perennials11.4.2 physio

21、logical and biochemical changes during senescenceprotein content: (biosynthesis degradation ) free aa degradation of rubiscodna and rna: (biosynthesis degradation ) chl. and mit. rrna are most sensitivephotosynthetic rate: (structure, chlorophyll, rubisco)respiration: slower than photosynthesis (str

22、ucture? uncoupling of oxidative phosphorylation) climactericbiological membranes: liquid-crystalsolid selective permeability, organelle structure, release of hydrolasesplant hormones: iaa, ga and ctk aba and eth 11.4.3 mechanisms of senescence11.4.3.1 dna damagesdna damages and repair, accumulation

23、of damages. mistaken proteins. 11.4.3.2 free radical injuriesfree radical balance11.4.3.3 regulation of plant hormonesdelay: iaa, ga and ctkpromote: aba and eth+ + iptipt genegene controlcontrolplant hormone balancedelay: breaking down of attraction of nutrition 11.4.3.4 programmed cell death: pcd p

24、cd: the process whereby individual cells activate an intrinsic senescence program.factors: inside cellsprogrammed: morphological, biochemical, molecular (gene)universal: embryogenesisnew seed11.4.4 environmental factors influencing senescencetemp. :high/lowlight: light/dark, ld/sdgas: o2/co2water: d

25、rought/flood mineral elements: n, ca ag, ni11.5 physiology of plant abscission11.5.1 abscission and its typesabscission: organelles depart from mother plant naturallynormal abscission: induced by senescence and maturation.stressed abscission: induced by stress.physiological abscission: vegetative/re

26、productive 正常条件下，适当的脱落，淘汰掉一部分正常条件下，适当的脱落，淘汰掉一部分衰弱的营养器官或败育的花果，以保持一定株衰弱的营养器官或败育的花果，以保持一定株型或保存部分种子，这样的脱落是植物自我调型或保存部分种子，这样的脱落是植物自我调节的手段。在不良环境条件下，叶、花幼果也节的手段。在不良环境条件下，叶、花幼果也会提早脱落，这是对环境的一种适应。但过度会提早脱落，这是对环境的一种适应。但过度或不适时的脱落往往会影响农业收成。或不适时的脱落往往会影响农业收成。11.5.2 mechanisms of abscission11.5.2.1 separation layer and abscission zoneseparation layer synthesizes and secretes wall hydrolases, dissolving the middle lamella and disrupt