Expression pattern of tobacco cyclin genes.

We have previously isolated three cDNA clones (Ntcyc25, Ntcyc27, Ntcyc29) encoding mitotic cyclins from tobacco (Nicotiana tabacum), and in this report we describe the expression patterns of these genes. RNA gelblot analysis showed that the mitotic cyclin genes were expressed predominantly in actively dividing meristematic tissues such as the shoot apex and young developing leaves. In situ hybridization analysis indicated that while theNtcyc29 gene was expressed consistently at low levels in shoot apex, but its transcripts were found at relatively high levels in the flower bud, indicating the possibility that theNtcyc29 product plays a role in flower development. TheNtcyc25 andNtcyc29 genes were expressed differentially in the root apex during the cell cycle, confirming the result obtained using synchronized-cultured tobacco cells. These results suggest that the transcriptionally regulated cyclin genes may be important in controlling cell division in tobacco.