Mitochondrial ABC Transporter ATM3 Is Essential for Cytosolic Iron-Sulfur Cluster Assembly.

The mitochondrial ATP-binding cassette transporter ATM3 has been studied in Arabidopsis. Its function, however, is poorly understood in other model plant species. This study reports that the ATM3 is required for cytosolic iron-sulfur cluster assembly and is essential for meristem maintenance in rice (). The loss of function of is lethal in rice at the four-leaf stage. In the T-DNA insertion mutant, the fourth leaf fails to develop and the lateral roots are short. Cytosolic iron-sulfur protein activities were significantly reduced in both and RNA interference transgenic lines. The expression profiles of many iron metabolism genes were altered in the and RNA interference lines. Glutathione metabolism was impaired and reactive oxygen species, particularly superoxide, accumulated in Promoter-β-glucuronidase staining of the transgenic line indicated that is highly expressed in lateral root primordia, root tip meristem zones, and shoot apical meristem regions. The average cell size was significantly greater in than in the wild type. Massive cell death occurred in the root tip meristem zone. Quantitative RT-PCR revealed transcriptional reprogramming of the genes in the and RNAi lines involved in DNA repair and cell cycle arrest. Our results suggest that the mitochondrial ATM3 is essential for iron homeostasis in rice.