01:119:116 Lecture Notes - Lecture 11: Meristem, Auxin, Axillary Bud
22 Apr 2016
School
Department
Course
Professor
Document Summary
Plant hormones - organic compounds, chemical messengers; control specific physiological responses in plants; plant growth regulators. Interact with each other (often difficult to determine cause of specific effect) Natural or synthetic: tropisms - directional growth in response to environmental stimulus. Auxin - 1st plant hormone discovered; directional growth toward light. When coleoptile (1st part of grass seedling to emerge from soil) exposed to light from one direction bend in that direction. Shielded or removed tip = no bending. Postulated: signal transmitted from tip to elongating region. Separated tip from rest of coleoptile w/ gelatin cube = bend. Separated with mica (impermeable) = no bending: group of natural and artificial hormones (synthetic: iaa, indoleacetic acid) Main site of production - shoot, apical meristem. Transport is polar - unidirectional, shoot root. Active transport, requires atp: role of auxin in cell elongation - stimulates elongation of cell in developing shots by elongating primary cell walls.
