Discovery of Plant Growth Regulators

Plant growth regulators- This are small biomolecules which are synthesized by plants and transported to different region for controlling growth and physiological functions in plants. These are of five types- auxin, gibberellins, cytokinins, abscisic acid, ethylene.

Discovery of the five plant growth regulators are quite accidental and those are described below-

1. Darwin and his son was the first to observe the growth of coleoptile in cannery grasses whose scientific name was Phalaris canarensis. They are first observed that the growth of coleoptile occurs towards the sunlight which is called phototropism and it is responsible for the bending of the portion of the plants. After some experiment which was concluded that tip of the coleoptile was the region of plant where the transmittable influence that cause the bending of entire coleoptile.
Doing the experiment for the long time it was discovered the reason for the beginning of the tip of coleoptile and the first plant growth regulator was discovered which was known as auxin by age wind. In the tips of the Avena seedlings.

2. Foolish Seedling disease of rice or the bakaney is a disease which are constituted of weak stem, elongated stem and there was less or no seed production. Pathologist are there after doing some experiments able to discovered the presence of fungus called Gibberella fujikuroi. From that fungus gibberellins is discovered which is another type of plant growth regulator.
In the year of 1926 Kurosawa discovered some symptoms in the un effected rice plants. Then they done one experiment where they collected the purified filtrate of the solution and applied to the plant. This substance was latter named as gibberellin.

3. Skoog of USA and his co workers during their study of nutritional requirements study and they derive the tissue culture from the internodal segments of tobacco stems. It was observed that there was callous only proliferated within it due to addition of auxin nutrients medium and this is supplementary with one of the following extract like- vascular tissue or yeast extract or coconut milk or DNA.
The responsible substance was discovered by Skoog and Miller and that was latter known as cytokines. When the cytokinin was first discovered they named it as kinetin.

4. In 1967 Abscisic Acid was discovered as it was observed to be interfering with the auxin response during the discovery and experiments which was going on regarding the plant growth regulator. It was isolated by the process of paper chromatography and in listed it into the plant growth regulator community.

5. It has been observed that during the Export Import of fruits or during storage of fruits ,ripen fruits and rotten fruits can enhance the ripening of the unripe fruit when they were kept together. 1910 scientists discover the release of volatile substances from the ripening oranges which induces the ripening of unripened bananas stored nearby. In 1934 R. Gane provided some undisputable observation that the volatile substances was the ethylene and he proved it by chromatography experiments.

Eleventh Grade

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