Question

The natural plant hormones were first isolated from

• A. Cotton fruits, spinach leaves and rice plant
• B. Avena coleoptiles, spinach leaves and fungus Gibberella
• C. Human urine and corn germ oil
• D. Human urine and rice plant

Answer 1

Answer: (C)

Human urine and corn germ oil

The discovery of each of the five major groups of plant growth regulators have been accidental. Auxins (from Greek auxein: to grow) was first isolated from human urine.The term auxin is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic compounds having certain growth regulating properties. Cytokinins have specific effects on cytokinesis, and were discovered as kinetin (a modified form of adenine, a purine) from the autoclaved herring sperm DNA. Kinetin does not occur naturally in plants. Search for natural substances with cytokinin-like activities led to the isolation of zeatin from corn-kernels (corn germ oil) and coconut milk.

Thus, the correct answer is option C.