Abstract
Rapid growth of leaf primordial organ to mature leaf is crucial step for survival of plant seedlings. The leaf size is determined by size and number of leaf cells. The size of leaf cell is closely associated with its ploidy level. Recently, we found that the ploidy level in leaf cells are largely affected by the function of plant transcriptional co-activator, AtMBF1, by functional conversion of the transcriptional co-activator into transcriptional co-repressor by fusing it to SRDX, a strong repression domain of transcriptional repressor, in its C-terminal end. The dominant-negative effect of over expression of the chimeric protein (AtMBF1-SRDX OE) in plant induced reduction of size of leaf epidermal cells and reduction of ploidy level of leaf cells. Only two peaks (2C and 4C nuclei) with major peak corresponding to 2C nuclei were observed in first leaves from AtMBF1-SRDX OE.
