Abstract
Many G2/M phase-specific genes in plants contain mitosis-specific activator (MSA) elements, which act as G2/M phase-specific enhancer and bind with R1R2R3-Myb transcription factors. Here, we examined the genome-wide effects of overexpression of NtmybA2, one of the R1R2R3-Myb transcription factors in tobacco. Microarray analysis was performed with stably transformed BY2 cell lines that ectopically express NtmybA2 or its hyperactive form lacking the negative regulation domain. This analysis revealed that overexpression of the truncated hyperactive form of NtmybA2, but not its full-length from, preferentially up-regulates many G2/M phase-specific genes in BY2 cells. We determined the promoter sequences of several such up-regulated genes, showing that all of them contain MSA-like motifs in their promoters. We propose that transcription of many G2/M phase-specific genes in tobacco is commonly and positively regulated by NtmybA2, in most cases through its direct binding to the MSA elements.
