Embryoless Wheat Grain: A Natural System for the Study of Gibberellin-induced Enzyme Formation

Yorkstar wheat, grown in New York State, has a high percentage (10-11) of grains without embryos. The embryoless grains have viable aleurone layers and show no sign of injury. These grains are able to support alpha-amylase synthesis only in the presence of gibberellin A(3) (GA(3)). In the absence of GA(3) some protein synthesis occurs in embryoless grains during the early hours of soaking, indicating that such activity occurs prior to and independent of GA(3) induction of alpha-amylase. The level of beta-amylase on a dry weight basis is the same in embryoless and normal grains and decreases with time of soaking. In the presence of GA(3), beta-amylase decreases at a slower rate. Isoenzymes of alpha-amylase from GA(3)-treated embryoless and normal grains show quantitative as well as qualitative differences. Cycloheximide (60 mug/ml) completely inhibits the synthesis of alpha-amylase by embryoless grains. Of the RNA synthesis inhibitors, actinomycin D (60 mug/ml) was ineffective while 6-methylpurine (60 mug/ml) gave 65% inhibition without decreasing the number of isoenzymes.