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Embryoless Wheat Grain

A Natural System for the Study of Gibberellin-induced Enzyme Formation ¹

New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456, Laboratory of General and Biological Chemistry, State University of Ghent, Ghent, Belgium

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 -amylase synthesis only in the presence of gibberellin A₃ (GA₃). In the absence of GA₃ some protein synthesis occurs in embryoless grains during the early hours of soaking, indicating that such activity occurs prior to and independent of GA₃ induction of -amylase. The level of -amylase on a dry weight basis is the same in embryoless and normal grains and decreases with time of soaking. In the presence of GA₃, -amylase decreases at a slower rate. Isoenzymes of -amylase from GA₃-treated embryoless and normal grains show quantitative as well as qualitative differences. Cycloheximide (60 µg/ml) completely inhibits the synthesis of -amylase by embryoless grains. Of the RNA synthesis inhibitors, actinomycin D (60 µg/ml) was ineffective while 6-methylpurine (60 µg/ml) gave 65% inhibition without decreasing the number of isoenzymes.