Fig. 6

Expression levels of genes related to DNA replication and the cell cycle. A Changes in the expression levels of DNA replication-related genes at 0–5 days of differentiation culture. B Changes in the expression levels of cell cycle-related genes at 0–5 days of differentiation culture. C RT-qPCR detection of the expression of cell cycle-related genes (PagCDKB1;2, PagCDKD1;1, PagCYCA3;4, PagCYCB2;4, PagCYCD1;1, PagCYCD3;2, PagCYCD6;1, and PagCYCH;1) in poplar leaves in differentiated cultured for 0–5 days. D RT-qPCR detection of the expression of cell cycle-related genes (PagCDKB1;2, PagCDKD1;1, PagCYCA3;4, PagCYCB2;4, PagCYCD1;1, PagCYCD3;2, PagCYCD6;1, and PagCYCH;1) in poplar stem segments in differentiated cultured for 0–5 days. Expression was estimated by RT-qPCR normalized to PagACTIN expression. E RT-qPCR detection of the expression of cell cycle-related genes (NtCDKB1;2, NtCDKD1;1, NtCYCA3;4, NtCYCB2;4, NtCYCD1;1, NtCYCD3;2, NtCYCD6;1, and NtCYCH;1) in tobacco leaves in differentiated cultured for 0–5 days. Expression was estimated based on RT-qPCR normalized to NtACTIN expression. Error bars represent the SD (data are the means of the three biological replicates). P < 0.05 is considered significantly different and is shown by different letters