Analyses of regulation of chloroplast division by PDV2

Abstract

Consistent with their endosymbiotic origin, chloroplasts only proliferate by division. To establish the permanent endosymbiotic relationship, the host cell has been regulated proliferation of chloroplasts during proliferation of the cell. Furthermore, in higher plants, size and number of chloroplasts changes according to cell differentiation. But the regulatory mechanism of chloroplast division is poorly understood. Recently, we found that the overexpression of PDV2, which was identified as a component of chloroplast division machinery, caused the increase of number of chloroplasts per cell and the decrease the size of chloroplasts. The expression of PDV2 was high in shoot apical meristem and decreased according to leaf development. We also found that cytokinin increased PDV2 expression. These results indicate that PDV2 regulates chloroplast division during leaf development under cytokinin signaling pathway. We also analyze a PDV2 ortholog in Physcomitrella patens, and the functions of PDV2 in land plants will be discussed.