Abstract
Recently, close relation between the segregation of nucleoids and the cell division has been clarified in Escherichia coli. However, the relationship between nucleoid segregation and plastid division is poorly understood in plants. We developed a new fluorescent probe for live visualization of plastid nucleoids. The PEND protein contained a DNA-binding domain called cbZIP at its N-terminus. In transformants of Arabidopsis thaliana, cbZIP-GFP fusion proteins were localized in the nucleoids of plastids. In resting chloroplasts, nucleoids existed as small particles. During the division of plastid, nucleoids formed a fibroid structure, which suggests an active segregation of nucleoids. This also point to a mechanism of coupling of nucleoid partition and plastid division, as in the case of the chromosome distribution and segregation in eukaryotic cell division. Moreover, during the division of plastid in Cyanidioschyzon merolae, nucleoids were connected across the plastids. Therefore nucleoid segregation machinery may be present widely in plants.
