PLANT PHYSIOLOGY , Vol 110, Issue 4 1267-1273, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Transcriptional and Posttranscriptional Regulation of Dormancy-Associated Gene Expression by Afterripening in Wild Oat
Bailin. Li and M. E. Foley
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-1155
To investigate whether the afterripening-induced changes in gene expression
are at the transcriptional or posttranscriptional level in wild oat (Avena
fatua) seeds, we chose four dormancy-associated genes to estimate their
relative transcription activities and the stability of their corresponding
transcripts in afterripened and dormant embryos. The transcription
activities for those genes were 1.5 to 7 times higher in dormant embryos
than in afterripened embryos 24 h after incubation, as determined by
nuclear run-on assays. The half-lives of the transcripts in afterripened
and dormant embryos were estimated by the use of actinomycin D. The
application of actinomycin D resulted in the stabilization of the
transcripts. Nevertheless, the results indicated that the half-lives of the
transcripts were much greater in dormant embryos than in afterripened
embryos. Considering the great differences in the steady-state levels and
the half-lives of the mRNAs, and the relatively small differences in
transcription activities of the genes between afterripened and dormant
embryos, we conclude that afterripening regulates the expression of
dormancy-associated genes in excised embryos mainly at the
posttranscriptional level and that transcriptional control plays a minor
role.
