Abstract
It is known that one plant-specific type of dynamin-related proteins (DRP5B) is associated with the late stage of chloroplast divisions in Arabidopsis thaliana and red alga Cyanidioshyzon merolae. In A. thaliana, AtDRP5B (arc5) mutants have enlarged, dumbbell-shaped chloroplasts. We identified three homologs of AtDRP5B (PpDRP5B-1, -2, and -3) from the moss Physcomitrella patens. The amino-acid identity between AtDRP5B and PpDRP5Bs was 54.7% for PpDRP5B-1, 54.9% for -2 and 55.0% for -3. Each PpDRP5B-1 or -2 single knockout (KO) lines was generated by a P. patens gene-targeting technique. The average chloroplast number of PpDRP5B-1 and -2 single KO line is 46.4 ± 5.5 and 46.2 ± 5.3, respectively, and is the statistically same to that of wild type cells (49.3 ± 5.5). Therefore, PpDRP5B-1 and -2 double KO mutants were created. In the double KO lines, cells contained fewer and larger chloroplasts (30.03 ± 6.4 chloroplasts per cell).
