Cytokinin regulates the expression of a soybean beta-expansin gene by a post-transcriptional mechanism.
The cytokinin-inducible soybean mRNA Cim1 accumulates 20-60-fold upon cytokinin addition to cytokinin-starved soybean suspension cultures. In this report, we demonstrate that cytokinin-induced stability of the Cim1 mRNA plays an important role in the accumulation of the message. We also present evidence that cytokinin-induced Cim1 stability is blocked by the addition of the protein phosphatase inhibitor okadaic acid. Thus, we suggest that protein phosphatase activity is required for the cytokinin-induced stability and subsequent accumulation of Cim1 in soybean cells. The deduced amino acid sequence of the Cim1 protein product is similar to the group I pollen allergens from various plants, which constitute a subfamily of expansin proteins. The relatedness between Cim1 and the expansins supports our hypothesis that the protein product of Cim1 is localized to the cell wall and suggests a role for Cim1 in cytokinin-regulated cell wall expansion. Thus, post-transcriptional regulation of Cim1 by cytokinin may represent a molecular link between cytokinin and changes in cell shape and size.
Downes
B P
BP
Department of Biology, Indiana University-Purdue University at Indianapolis, 46202-5132, USA.
Crowell
D N
DN
D003583:Cytokinins / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D030262:Soybean Proteins; D013025:Glycine max / Q000235:genetics*
D003583:Cytokinins; D010940:Plant Proteins; D030262:Soybean Proteins; C089150:cim 1 protein, soybean