chapter 8 Plant Hormone
chapter 8 Plant Hormone
平平 tare hormones The definition(定义) for plant hormone:an organIc(有机) compound synthesized(合 Fi) in one part of a plant and can be translocated(运输) to other parts, where in very low concentrations(浓度) it causes a physiological response
What are hormones? The definition (定义） for plant hormone: an organic （有机） compound synthesized（合 成） in one part of a plant and can be translocated （运输） to other parts, where in very low concentrations （浓度）it causes a physiological response
Six recognized groups of plant hormones HORMONE STRUCTURE PRECURSOR SoURCE MAJOR ROLES Abscisic Acid isopentenylmany seed deve opment pyrophosphate tissues dormancy (PP) stomata closure 脱落酸 甲瓦龙酸 Auxin COol chorismate shoot apex . cell elong ( tryptophan cell division precursor root initiation 生长素 H3ndn色氨酸 Brassinosteroids isopentenyl cell elongation and (Brassinolide pyrophosphate tissues divsion inhibit root growth 菜素内酯 甲瓦龙酸 Cytokinins pentenyl oot apical· cell division (zeatin) pyrophosphate meristems . shoot initiation release apical dominance 5 AMP and 细胞分裂素 甲瓦龙酸 Ethylene methionine truit opening ssues senescence TIrene 甲硫氨酸 aking 乙烯 Gibberellins isopentenyl seeds cell elongation and (GA3) division (IPP) buds and· germinati 赤霉素 甲瓦龙酸
油菜素内酯 脱落酸 生长素 细胞分裂素 乙烯 赤霉素 Six recognized groups of plant hormones 5‘AMP and 甲瓦龙酸 甲瓦龙酸 甲瓦龙酸 甲瓦龙酸 色氨酸 甲硫氨酸
Learning objectives Understand historical aspects related to the discovery of the five hormones Know the basic synthesis and degradation ofthese hormones Understand the action mechanism for hormone action Know examples ofhormone function in plants
Learning objectives Understand historical aspects related to the discovery of the five hormones Know the basic synthesis and degradation of these hormones Understand the action mechanism for hormone action Know examples of hormone function in plants
Auxin family AuxIn.Greek word auxin, means to ncrease) 9 Principle auxin in plants is indole-acetic acid (IAA) 9 Auxin family includes structural lIly similar inco看3欲ekld tchloroindole 3-acet acd 0AA (A COAL compounds( some are吲哚乙酸 4-氯-吲哚乙酸 synthetic) 的二t-ot-coo a Somewhat similar in 吲哚丁酸 hdele-3-butyric si their function Three natural auxins
Auxin family Three natural auxins Auxin : Greek word auxein, means to increase) 吲哚乙酸 吲哚丁酸 4-氯-吲哚乙酸
Auxin history Darwin (1880) tip and is trans (no curvature) (no curvature) a(1919 stimul In 1926 F w. Went show at the active grow tin block coleoptile bending assay for
Auxin history
Auxin transportation 1. Phloem韧皮部 transport, the direction is determined by the concentration difference between the two parts From high to low 2. Polar transport, the direction in stems is base-seeking direction, from morphological apex to base(由形态学上顶端向基端方向)
1. Phloem韧皮部 transport, the direction is determined by the concentration difference between the two parts. From high to low. 2. Polar transport， the direction in stems is base-seeking direction, from morphological apex to base (由形态学上顶端向基端方向）. Auxin transportation:
Chemiosmotic polar diffusion theory Plasma 1. IAA enters the cell either membrane passively in the undissociated form(IAAH) or by secondary Permease active cotransport in the anionic form(IAA). AA H:5 Cell wall IAAH p Cytosol ATP 2. The cell wall is maintained at an acidic pH by the activity H 3. In the cytosol, which has a of the plasma membrane H neutral pH, the anionic form ATPase ATP (AA predominates Vacuole 4. The anions exit the cell via auxin anion efflux carriers that are concentrated at the basal ends of each cell in the AAH FIGURE 19.13 The chemiosmotic model for polar auxin transport. Shown here is one cell n a column of auxin-transporting cells (From Jacobs and Gilbert 1983
Chemiosmotic polar diffusion theory pH:5
Location of auxin synthesis Synthesized primary in active developing area, such as: young leaves, developing seeds, leaf and stem meristem Synthesized from tryptophan色氨酸 19) Tip removed Tip replaced Growth curvature on one side of develops without GUs reporter staining of coleoptile stump a unilateral light stimulus auxin synthesis in a leaf primordium and in vascular strand
Location of auxin synthesis Synthesized primary in active developing area, such as: young leaves, developing seeds, leaf and stem meristem. Synthesized from tryptophan色氨酸
Two forms of auxins Free auxin ------------bound auxin Active Inactive Conjugated with sugar and other chemicals Conjugated auxin: form of storage and transport; it also functions as a way of regulating the amount of free auxin and detoxicating the possible harm caused by too high concentration of auxin
Two forms of auxins Free auxin ------------bound auxin Active Inactive Conjugated with sugar and other chemicals Conjugated auxin: Form of Storage and transport; it also functions as a way of regulating the amount of free auxin and detoxicating the possible harm caused by too high concentration of auxin