Different rates of development of α-amylase in distal endosperm ends of germinated (malted) Chariot and Tipper Barley varieties

Chariot Barley had a faster malting rate than Tipper. Even when the total levels of the aleurone-produced enzyme a-amylase were similar in both Chariot and Tipper, the distal ends of the grains of Chariot developed a-amylase at a faster rate than the corresponding endosperm ends of Tipper. The excised aleurone layers of Chariot and Tipper had similar potentials to produce a-amylase. Therefore the faster rate of development of a-amylase in the distal ends of the grains of Chariot may reflect faster transport of active gibberellic acid through the aleurone layer. Differences in the rates of transport of gibberellic acid through the plasmodesmata of the aleurone layer may determine the efficiency of production and distribution of endosperm-degrading enzymes during malting. The transport of gibberellic acid in the aleurone layer was facilitated by high moisture levels.