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