Plant Hormones — Tech Evolutions

Entry	Year	Description	Impact
Discovery of Auxin (Frits Went)	1926	Frits Went isolated and identified auxin (Indole-3-acetic acid, IAA) from oat coleoptiles, proving the existence of a chemical substance that promotes plant growth. This marked the first definitive identification of a plant hormone.	Revolutionized plant physiology, establishing the concept of chemical regulation in plants and paving the way for the discovery of other phytohormones. It laid the foundation for modern plant hormone research and agricultural applications.
Identification of Gibberellins (Yabuta & Sumiki)	1930s	Japanese scientists, particularly Yabuta and Sumiki, isolated gibberellins from the fungus *Gibberella fujikuroi*, which caused 'foolish seedling' disease in rice. They identified the active compounds responsible for abnormal stem elongation.	Led to the understanding of gibberellins' role in stem elongation, seed germination, and flowering. Opened avenues for commercial applications in agriculture, such as increasing fruit size and breaking dormancy.
Discovery of Cytokinins (Skoog & Miller)	1950s	Folke Skoog and Carlos Miller discovered kinetin, a cytokinin, while studying cell division in tobacco pith cultures. They demonstrated that cell division required both auxin and this new factor.	Crucial for understanding cell division and differentiation in plants. Became fundamental to plant tissue culture and micropropagation techniques, enabling rapid clonal multiplication and genetic manipulation of plants.
Characterization of Abscisic Acid (ABA)	1960s	ABA was independently discovered by several research groups (e.g., Addicott, Wareing) and initially named 'dormin' or 'abscisin II' due to its roles in dormancy and abscission. Its chemical structure and physiological effects were elucidated.	Established ABA as a key regulator of plant stress responses, particularly to drought, and a major inducer of dormancy. Its discovery provided insights into how plants adapt to adverse environmental conditions.
Confirmation of Ethylene as a Hormone (Burg)	1960s	Earlier observations of ethylene's effects on fruit ripening were confirmed by H. K. Burg and others, establishing it definitively as a naturally occurring gaseous plant hormone with diverse physiological roles.	Led to widespread commercial applications in fruit ripening and post-harvest management. Understanding ethylene's role has been critical for reducing food waste and optimizing agricultural supply chains.