Virus induced gene silencing of AtCDC5 results in accelerated cell death in Arabidopsis leaves

CDC5, a Myb-related protein, is reported to be essential for the G2 phase of cell cycle in yeast and animals, but little is known about its function in plants. In this study, Arabidopsis thaliana CDC5 (AtCDC5) is found to be nuclear localized, and the C-terminus of this protein is of transcriptional activation activity in yeast. By taking advantage of the virus induced gene silencing (VIGS) technique, we analyzed the phenotypes of the plants in which AtCDC5 is specifically silenced. The AtCDC5 VIGS plants died before bolting, in which accelerated cell death was detected. Further analysis showed that the transcripts of AtSPT and SAG13, but not SAG12, accumulated in these AtCDC5 VIGS plants, suggesting that the accelerated cell death is different from that occurred during leaf senescence. Furthermore, silencing of AtCDC5 by VIGS in either wild-type, npr1 or nahG plants all induces cell death, suggesting that SA is not crucial for the AtCDC5-associated cell death.