Patterns of B-type cyclin gene expression during adventitious rooting of micropropagated cork oak

The aim of our study is the identification of the critical points in the rooting process at the molecular level for possible improvement of the propagation of cork oak. The rhizogenic potential of woody plants depends on both genotype and developmental stage. To investigate the role of cyclin transcription in the regulation of cell division during adventitious root induction, we have analysed the temporal expression of a member of the cyclin gene family. The histological modifications that occur during the root induction and formation processes as a consequence of auxin treatments can be detected by the technique of tissue printing for hydrogen peroxide (H2O2). Thus a H2O2 printing assay was performed in parallel with cyclin expression studies. We report the cloning and sequencing of a B-type cyclin genomic fragment from micropropagated cork oak using gene-specific and genotype-independent oligonucleotide primers to conserved regions of the gene. After 48 h of auxin induction, the expression of this B-type cyclin increased, possibly in association with the first cell divisions. The expression observed in control shoots may reflect unorganised cell divisions associated with callus formation.