By 1939, the substance had been isolated from the fungus and named gibberellin . In the cereal grain barley, the cotyledon produces gibberellic acid when germination begins. The GA is transported to the aleurone layer, a layer of living cells surrounding the non-living endosperm cells that store starch. The amylase breaks the starch down to glucose, which can be used by the germinating seedling for growth. This process is well-studied in barley because the malting step of brewing is the breakdown of starch in germinating barley seeds.
Commercial breweries add gibberellic acid to ensure complete starch breakdown.
Gibberellic acid will substitute for a daylength response and probably also for a cold temperature requirement , and induce bolding if it is applied to the rosette form of plants. This permits seed production to be completed within one year. It was originally thought that cytokinins were breakdown products of DNA, because their effect was associated with coconut milk, which is rich in nucleic acids. Coconut milk is the liquid endosperm of coconut seeds, and was used to artificially culture other plant embryos. Several additional cytokinins have now been isolated from plants.