title: Expression of Storage Protein Genes in Developing Wheat (Triticum aestivum L.) Seeds : Correlation of RNA Accumulation and Protein Synthesis.
abstract: Ribonucleic acid and protein synthesis in developing wheat kernels have been studied through in vivo labeling of wheat heads in culture. In INIA 66R wheat labeled with [5-(3)H]uridine for 24-hour periods between 9 and 33 days after flowering, the total rate of RNA accumulation in endosperm/testa pericarp tissues was highest in the youngest seeds, and declined with increasing seed age. In contrast, the rate of accumulation of poly(A)(+) RNA approximately doubled between 12 and 15 days after flowering, reached a maximum between 15 and 18 days, and declined to half the maximum rate by 24 days. Protein synthetic capacity, measured by in vitro translation of extracted seed RNA, increased in a developmental pattern similar to that of poly(A)(+) RNA accumulation, but remained near maximal through 24 days after flowering. Gliadins were prominent in the in vitro translation products. When seed protein was labeled in vivo with l-[(3)H]leucine, extracted, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a significant change in the protein synthesis profile was apparent between 12 and 15 days after flowering, and was coincident with a marked increase in storage protein synthesis. Qualitatively similar characteristics were exhibited by the cultivar Cheyenne, although in a shorter developmental period. These results are consistent with a direct relation between levels of mRNA and rates of protein synthesis in developing wheat seeds, with a relatively long storage protein mRNA lifetime, and with control of storage protein gene expression primarily at the level of mRNA transcription.
authors: United States Department of Agriculture, Western Regional Research Center, Science and Education Administration, Agricultural Research, Berkeley, California 94710.
authors: F C
authors: FC
authors: Greene