8planthormone.ppt
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1、Chapter 8 Plant growth substance,Plant growth substance: Plant hormone plant regulator,Plant hormones: are naturally occurring, organic substance that can be transported from the synthetic tissue to a specific target tissue where, at low concentration,exert a profound influence on physiological proc
2、ess. IAA GA CTK ABA Eth,Plant growth regulators is normally used to denote synthetic compounds that exhibit plant hormonal activity.,Section 1 Auxins 1.1 discovery of IAA,1.2 Distribution and transportation of IAA in plant body,IAA Polar transport:IAA moves from the apex to the base, is unidirection
3、al transport。,0.5-1.5cm/h, Cell-cell transport fashion Require metabolic energy,In coleoptiles and vegetative shoots, basipetal transport predominates. Most of the auxin in the root is transported acropetally(向顶的) and transport occurs mainly in the stele. Stimulating the pericycle to form branch roo
4、ts. IAA is transported nonpolarly in the phloem.,1.3 Biosynthesis of IAA 1.3.1 Biosynthesis location: coleoptiles, vegetative shoots, young leaves,develping seed and fruits. 1.3.2 Steps of Biosynthesis tryptophan 1) indole pyruvate pathway 2) tryptamine pathway 3) indole acetonitrile pathway 4) indo
5、le-3-acetamide pathway,An orange pericarp (orp) maize cob showing the expected two-gene recessive trait, the orange kernels carry both mutant genes,Mutants for tryptophan nutrition deficient Maize -orp mutant, trp synthase -subnuit point mutant, 50 time high IAA-conjugate,1.4 Degradation of IAA 1.4.
6、1 enzyme degradation 1.4.2 light oxidation Free auxin Bound auxin: for storage transport detoxifcation,1.5 Mechanism of IAA,1.6 Physiological effects and application of IAA,(1)、Enhancing elongation of cell and organ.,Enhancing fruit setting and parthenocarpy(单性结实) production of seedless fruit,(5) En
7、hancing falling flower and fruit thining(疏花疏果) (6) Inhibiting sprouting of tomato。 (7) Enhancing pineapple flower and controlling sexual differentiation. (8) As a herbicide。,Section 2 Gibberellic acid (GA) 2.1 Discovery of GA foolish seeding gibberlla fujikuroi. Basic structure: gibberellane (赤霉烷)di
8、terpene(双萜) C19-GA: high activity C20-GA: C7: -COOH (activity),2.2 GA transport: double directions in xylem。 biosynthesis location: vegetative shoots, young leaves,develping seed and fruits. GA-conjugate: GA-glucose.,Histochemical localization of GA1 promoter activity indicating CPS expression durin
9、g the development of transgenic Arabidopsis containing the GA1 promoter-GUS gene fusion pGA1-103.,2.3 Synthesis and transport of GA,Precursor: mevalonic acid(甲瓦龙酸)? PGA IPP GGPP,Steps of Biosynthesis proplastids: GGPP ent-kaurene ER(endoplasmic reticulum): form GA12-aldehyde cytosol: formation of al
10、l other GA,2.4 Mechanism of GA,2.5 Physiological role and application of GA (1) Promoting elongation of stem and division of cell.,Untreated cabbage plants,Similar cabbage plants that have been treated with gibberellins,(2) Breaking dormancy and promoting germination of seed.,(3) Promoting bolting a
11、nd flowering,(4) Enhancing fruit setting and parthenocarpy,(5) Controlling sexual expression,Section3 Cytokinin(CTK) 3.1 Discovery of CTK 1940s, Van overbeak, coconut milk 1954, Skoog, Jablonski, tabaco, explants with vascular cylinder yeast extract-DNA? 1955, Miller, heat-induced degradation of the
12、 DNA-kinetin 1963, Letham, Zeatin 1965, Skoog, “cytokinin”,3.2 Transportation and Biosynthesis of CTK 3.2.1 Biosynthesis location of CTK。 Root apical meristems are major sites of synthesis of the free CTK. Maize young embryo and young developing leaves 3.2.2 Transportation of CTK Transportation thro
13、ugh the xylem into the shoot. Transportation as zeatin ribosides(玉米素核苷) External CTK can not move.,3.2.3 Biosynthesis of CTK,Precursor: mevalonic acid ipp ip zeatin,T-DNA IPT gene,冠瘿瘤是由土壤杆菌感染引起的肿瘤。至少在60多科,200多属,上千种的高等植物中存在。很多木本经济植物,都可以被细菌感染而发生这种肿瘤。冠瘿瘤的外观呈球形,表面凹凸不平,大小可自几毫米到十几厘米,或更大些,常发生在植株近地表处或嫁接处。冠瘿
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