Lateral electrical potential following asymmetric auxin application to maize coleoptiles

Area of Science:

• Plant Physiology
• Molecular Biology
• Biophysics

Background:

• Plant hormones, particularly auxins like indoleacetic acid (IAA), play critical roles in plant growth and development.
• Electrical signaling is increasingly recognized as a component of plant physiological responses.
• Understanding the rapid biophysical effects of auxin is crucial for deciphering plant growth mechanisms.

Purpose of the Study:

• To investigate the early temporal dynamics of electrical potential changes in maize coleoptiles following asymmetric auxin application.
• To characterize the nature and magnitude of auxin-induced electrical responses.
• To explore the relationship between auxin concentration gradients and electrical potential shifts.

Main Methods:

• Asymmetric application of indoleacetic acid (IAA) to maize (Zea mays L.) coleoptiles.
• External monitoring of lateral electrical potential using static-drop electrodes.
• Analysis of the time course of potential changes at the coleoptile surface.

Main Results:

• An initial, transient negative potential change (approx. -1 mV) was observed on the side of strong auxin application.
• This early negative effect lasted for approximately 15 minutes.
• A subsequent, strong, and sustained positive lateral potential (up to +12 mV) developed on the auxin-treated side, dependent on auxin concentration increases.

Conclusions:

• Asymmetric auxin application induces rapid and distinct changes in the lateral electrical potential of maize coleoptiles.
• The early electrical response to auxin is biphasic, involving an initial negative potential followed by a positive potential.
• The magnitude of the initial auxin-induced electrical effect is sensitive to the applied auxin concentration gradient.