Physiology of Seed Plants. Regulating Growth and Development: The Plant Hormones. Auxins Cytokinins Ethylene Abscisic Acid Gibberellins. Hormones. Chemical signals that help both plants and animals regulate and coordinate metabolism, growth, and differentiation.
In response to light
an “influence” that causes
bending is transmitted
from the tip to area below
In plants variety of pathways to produce
found in shoot apical meristems, young
leaves and developing fruit and seeds.
Mutants lacking either auxin or cytokinin
Have yet to be found- mutations eliminating
Them are lethal
synthesis along the margin of a
Site corresponds to the location
of cells that will differentiate into
a hydothode (gland like structure)
GIS reporter gene detects auxin
stems represented here by a segment of hypocotyl from a
the phloem of the vascular cylinder whereas the polar transport
occurs in the epidermis and cortical parenchyma cells
Basipetal polar movement of auxin from
Above the arrow and then around the wound
IAA induced xylem regeneration around a wound
put in a medium containing auxin or free of it.
Without auxin, adventitious roots can developed. This is the principle of cuttings.
However, with auxin, root development is much better.
- With equal concentrations of the two hormones, a callus is obtain. The callus is the result of the anarchic proliferation of cells which are more or less differentiated but which cannot organized them and form tissues and distinct organs.
Auxin prevents abscission (prevents preharvest)
High concentration does the opposite