Who discovered Auxin?

The phenomenon of phototropism was first studied by Charles Darwin and his son Francis Darwin through experiments on coleoptiles. They exposed coleoptiles to unidirectional light and observed that they bent towards the source.

By covering different parts of the coleoptiles, they discovered that the tip detects light. When the tip was covered, seedlings showed no bending, leading to the conclusion that the tip senses light and sends a messenger signal downward, causing the plant to bend.

Later, Frits Warmolt Went identified this messenger as a chemical substance transmitted from coleoptile tips. His experiments showed:

• When the chemical was distributed equally, coleoptiles grew straight.
• When distributed unevenly, coleoptiles bent towards the light.

He named this chemical auxin, and explained that it becomes unequally distributed in bending regions, promoting cell elongation and causing curvature.

Note

• Auxin is a key plant growth regulator that influences cell division, elongation, and expansion.
• Its effect depends on concentration, tissue type, and interaction with other factors.
• It can promote axial, lateral, or iso-diametric expansion and plays a vital role in plant development patterns.
• Auxins interact with other growth regulators to control differentiation and organ development.