The Discovery of Gibberellic Acid
At the turn of 20th century Japan, some rice seedlings grew extremely tall, falling over. Roots were shallow; chlorophyll was abnormally low. This condition was named bakanae ("foolish seedling"). In 1898, Shotaro Hori blamed a Fusarium fungus. In 1926, bakanae was attributed to a chemical secreted by the fungus. Lab culture-plate studies led to the isolation during the 1930s of a group of hormones thought to be a single substance, gibberellin.
Other People Are Reading
-
Importance
-
Rice, if seriously attacked, would represent an immense problem (it is second in world food production only to maize). Fortunately, that did not occur. Coating rice seeds with a fungicide eliminated the risk. Of positive importance, research did lead to the discovery of gibberellic acid, a diterpenoid acid, useful in silviculture and viticulture.
Discovery History
-
Although there were initial discoveries and isolation of gibberellins in the 1930s, difficulty in isolating pure material, and confusing identifications, followed by the development of war, slowed progress. Interest was rekindled in the 1950s in the United States. In addition to rice, the effect of gibberellins on bean seedlings was studied. Cultures from Japan were provided but, for some time, were unsatisfactory. After this was corrected, gibberellin research improved greatly. From gibberellins, pure acids were prepared, one of which was GA3 or gibberellic acid. Over the next few decades, more modern analytical techniques were used, resulting in the identification and isolation of well over a hundred gibberellins.
-
Useful Properties
-
Today, the gibberellins are of great economic importance in viticulture, most notably in increasing the size of fruit in Thompson seedless grapes. Testing is being conducted for other grape varieties, such as flame seedless and perlette grapes. GA3 is used at low levels, producing the following effects:
It promotes cell division and elongation.
It overcomes dormancy by forcing the breakdown of starch into a sugar used in synthesizing protein.
Premature flowering can be induced.
It can increase the size of fruit set.
Seed counts may decrease or disappear.
Application
-
Premature flowering may be induced with about 200 parts per million aqueous gibberellic acid. Seed germination should be about 10 times that concentration.
Health Advisory
-
Gibberellic acid is listed in material data safety sheets available online, but appears to be a minimal-risk material. Eye-protection should receive the greatest consideration.
-
References
Resources
- Photo Credit Gibberellic Acid Chemical Structure - Public Domain
