The Effects of Increased Cytokinins Provided by Activation of ipt/GUS Expression in Non-Invasive Conditions on the Transcript Levels of Selected Genes in Arabidopsis

Fusion genes of ipt-GUS and GUS-ipt in transcription manner were expressed in Arabidopsis under the control of pOp /LhG4 system in non-invasive conditions. The activated Arabidopsis showed increased cytokinins of 2-25 folds of their inactive lines depending on the order of the ipt/GUS gene fusion. This paper has investigated the effects of the endogenously increased cytokinins on the transcriptions of genes that are either involved in the cytokinin signaling pathway or in plant developmental aspects. The results showed that His-kinase CRE1 was more sensitive to the increased cytokinins than His-kinase CKI1. AHP4 was sensitive to the increased cytokinin only at the vegetative stages. The sensitivity of ARR4 to the increased cytokinins was earlier than ARR5. The inducible transcriptions of homeobox genes KNAT1 and STM were higher at the inflorescent shoot stages comparing to vegetative stages, which the sensitivity of STM was earlier than KNAT1. CHS transcript level was vigorously increased at vegetative stages. No change in mRNA levels of rbcS, cab and cdc2 in response to the increased cytokinins.