Abstract
Endoreduplication is a kind of cell cycle that increases nuclear DNA content(ploidy)without cell and nuclear division and is important for plant development.We screened mutants showing increased polyploidy from RIKEN Arabidipsis full length cDNA Overexpressor lines(FOX line).We found that one of FOX line F07144 showed increase in polyploidy in darkness and the corresponding gene encoded a homologue of mitochondrial translocator subunit TIM50.We checked sub-cellular localization of F07144 protein fusing GFP reporter and found that this protein was localized in mitochondria, so this F07144 protein can be designated as AtTIM50. Loss of function mutant showed decrease in polyploidy, reduced plant growth and low ATP levels compared to wild type plants. Transmission electron microscopic analysis showed appearance of large vacuolar space in loss of function mutant,while in overexpressor cristae was significantly thicker. Histochemical analysis of promoter using GUS reporter showed AtTIM50 was expressed in cotyledons and hypocotyls. Here, we demonstrate that AtTIM50 regulate endoreduplication through cellular ATP-levels.
