Ethylene-regulated gene transcription in carrot roots.

The plant hormone ethylene elicits many biochemical changes in target tissues. To investigate ethylene effects on expression of genetic information, cDNA clones corresponding to ethylene-induced carrot root mRNAs were constructed and isolated. RNA dot blot analysis showed that for the three clones studied peak cytosolic mRNA prevalence occurred at 21 h of treatment followed thereafter by rapid messenger decay. DNA filter excess hybridization to in vitro synthesized nuclear RNA showed that the ethylene-induced mRNA increase is engendered by transcription of previously quiescent genes. The kinetics and magnitude of changes in mRNA prevalence parallel changes in transcriptional activity; therefore the ethylene effect is primarily at the level of transcription. In vivo pulse labelling with [(35)S]-methionine showed that between 18 and 27 h of ethylene treatment a 2.5 fold increase in translational efficiency occurred for one message studied. The resulting protein is the predominant protein synthesized in carrots treated with ethylene for 27 h. Thus ethylene seemingly exerts multiple regulatory controls on the expression of genetic information.