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Articles

Relationship of Ribonucleic Acid Metabolism in Embryo and Aleurone to -Amylase Synthesis in Barley ^1,2

^a New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456

RNA metabolism of embryo and aleurone of barley grains (Hordeum vulgare L. cv. Himalaya) was studied to elucidate the role of these tissues in the control of -amylase synthesis and germination. The extent of ³H-uridine incorporated into various RNA classes of the embryo during the first 12 hours of germination was low but constant. Subsequently, there was a rapid increase in RNA synthesis of all fractions. In the aleurones, after 16 hours, a gradual decrease in ³H-uridine incorporation was observed, and by the time the synthesis of RNA in the aleurones had stopped, -amylase level was at its highest in the grain.

On transfer to accelerated aging conditions (43 C; 85% relative humidity), the grains lost their viability within 4 weeks. That this was due to a rapid deterioration of the embryo and not of the aleurone was apparent in studies on -amylase formation, RNA metabolism, and ATP content in grains in various physiological states reported here. Results presented here also reveal a marked influence of the embryo and GA₃ on the quality of the newly synthesized RNAs. Aleurones which lacked the impulse of embryo or GA₃ were capable of synthesizing RNA but these RNAs were less heterodisperse than RNAs from aleurones which were under the influence of an embryo or GA₃.

¹ This work was supported in part by grants from the Herman Frasch Foundation and American Seed Research Foundation to A. A. K. and the National Foundation for Collective Scientific Research No. 998 (Belgium) to H. A. V. O. and R. V.

² Approved by the Director of the New York State Agricultural Experiment Station as Journal Series Paper No. 2051.