CYTOKININ INDUCES A RAPID DECREASE IN THE LEVELS OF MESSENGER-RNAS FOR CATALASE, 3-HYDROXY-3-METHYLGLUTARYL COA REDUCTASE, LECTIN AND OTHERUNIDENTIFIED PROTEINS IN ETIOLATED COTYLEDONS OF CUCUMBER

Large-scale differential hybridization was performed to examine rapid changes in gene expression caused by a phytohormone, cytokinin, in eti olated cotyledons of cucumber (Cucumis sativus L.). We isolated 86 cDN A clones for mRNAs whose levels decreased within 2 h of the start of t reatment with N-6-benzyladenine (BA). Partial nucleotide sequences sho wed that some of the cDNAs were homologous to those for catalase, 3-hy droxy-3-methylglutaryl CoA reductase (HMGR) and a lectin. This is the first report that the levels of the mRNAs for those proteins are regul ated by a cytokinin in darkness. Together with previous results [Teram oto et al. (1993) Physiol. Plant. 87: 584, (1994) Planta 193: 573, (19 95) Planta 196: 387], the present study suggests that the cytokinin ac t to lower the levels of mRNAs transcribed from various genes in etiol ated cotyledons.