Abstract
It is now widely agreed that plastid is originated from a single cyanobacterial ancestor. Cyanobacterium contains peptidoglycan layer in its cell wall and peptidoglycan synthesis is essential for its division. Though no wall-like structure has been observed in chloroplasts of green plants, we found all of ten homologs to bacterial Mur genes for peptidoglycan synthesis pathway from Physcomitrella patens. Disruption of PpMurE in P. patens causes a small number of large chloroplasts in a cell by inhibition of chloroplast divisions. These results strongly suggest that P. patens Mur genes are still functional for peptidoglycan synthesis. To find out PpMurE function in P. patens, we carried out complementation test of P. patens PpMurE gene disruptant lines with Anabaena (Ana)MurE gene. PpMurE KO lines with expression of AnaMurE gene showed recovery of number and shape of chloroplasts. This result suggests that MurE genes in Anabaena and in P. patens are functionally identical.
