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Impermeant auxin analogues have auxin activity
M A Venis1, E W Thomas, H Barbier-Brygoo
1AFRC Institute of Horticultural Research, East Malling, Maidstone, ME19 6BJ, Kent, UK.
Planta
|November 8, 2013
Summary
Plant hormone (auxin) conjugates show activity only when plant cell walls are breached, suggesting receptors are on the cell surface. Auxins can trigger responses without entering the cell.
Area of Science:
- Plant Biology
- Molecular Biology
- Biochemistry
Background:
- Auxins are crucial plant hormones regulating growth and development.
- The precise location and accessibility of auxin receptors are key to understanding hormone signaling.
- Previous research suggests auxin receptors may be located on the plasma membrane.
Purpose of the Study:
- To investigate the role of the plant cell wall in mediating auxin perception.
- To determine if auxin conjugates can elicit a response without intracellular entry.
- To evaluate auxin activity of novel naphthaleneacetic acid protein conjugates.
Main Methods:
- Preparation of protein conjugates of 5-aminonaphthalene-1-acetic acid and 5-azido-naphthalene-1-acetic acid.
- Assessing auxin activity using pea (Pisum sativum L.) epicotyl elongation tests.
- Evaluating responses in abraded pea epicotyls and tobacco (Nicotiana tabacum L.) protoplasts (cell wall-deficient system).
Main Results:
- Auxin conjugates were inactive in standard pea epicotyl elongation tests.
- Abrading pea epicotyls to breach the cuticle restored auxin activity for smaller conjugates.
- Conjugates induced membrane hyperpolarization in tobacco protoplasts, irrespective of size.
Conclusions:
- Plant cell walls act as a barrier to auxin conjugate perception.
- Auxin receptors are accessible on the external surface of the plasma membrane.
- Auxins can initiate rapid and sustained cellular responses without crossing the plasma membrane.
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