Discovery of auxin

Auxin, a term we often hear. Auxin is a plant hormone. The most obvious effect of auxin is to promote growth, but the effect on the growth of stems, buds and roots varies depending on the concentration. Auxin also has the function of promoting callus formation and inducing rooting. Auxin acts in multiple locations and is primarily involved in cell wall formation and nucleic acid metabolism.

Auxin has powerful effects, especially in promoting plant growth, which will be beneficial to our survival and improve our quality of life.

Well, now let me talk about the discovery of auxin and see who discovered such a powerful auxin.

In 1880, when Darwin of Britain was studying the phototropism of plants using canary grass, he discovered that unidirectional illumination of the coleoptile would cause the coleoptile to bend toward the phototropism. Cut off the tip of the coleoptile or cover the coleoptile with an opaque tin foil cap and no phototropic bending will occur when irradiated with unilateral light. Therefore, Darwin believed that the coleoptile produced a downward-moving substance under unilateral light, causing the backlit side and the light-facing side of the coleoptile to grow at different speeds, causing the coleoptile to bend toward the light.

In 1910, Janssen's experiment proved that the influence generated by the tip of the coleoptile could be transmitted to the lower part through the agar plate.

Bayer's experiment in 1914 proved that the curved growth of the coleoptile was caused by the uneven distribution of the influence exerted by the tip in its lower part.

In 1928, Winter from the Netherlands placed the cut tips of oat coleoptiles upright on agar blocks. After a period of time, he removed the tips of the coleoptiles and placed the small agar blocks on one side of the cut coleoptiles. As a result, the side with the agar block grew faster and bent in the opposite direction. This experiment confirmed that a substance produced by the tip of the coleoptile diffused into the agar block, and when placed on the coleoptile, it could be transferred to the lower part of the coleoptile and promote growth of the lower part. Winter believed that this might be a substance similar to animal hormones and named it auxin.

In 1931, Kogl et al. in the Netherlands isolated a compound from human urine. When added to agar, it could also induce the bending of the coleoptile. The compound was proved to be indoleacetic acid. Later, Guo Ge and others also found indoleacetic acid (IAA) in plant tissues.

The most obvious function of auxin is to promote plant growth, but the concentration in roots, stems, etc. is different, and it can also promote plant growth, promote differentiation, maintain dominance, inhibit separation, promote fruiting, etc. This is also a herbicide. The discovery of auxin has contributed to the cause of science, and we need to thank the discoverer. This is undoubtedly a major discovery.