title: EMB2473/MIRO1, an Arabidopsis Miro GTPase, is required for embryogenesis and influences mitochondrial morphology in pollen.
abstract: The regulation of mitochondrial biogenesis, subcellular distribution, morphology, and metabolism are essential for all aspects of plant growth and development. However, the molecular mechanisms involved are still unclear. Here, we describe an analysis of the three Arabidopsis thaliana orthologs of the evolutionarily conserved Miro GTPases. Two of the genes, MIRO1 and MIRO2, are transcribed ubiquitously throughout the plant tissues, and their gene products localize to mitochondria via their C-terminal transmembrane domains. While insertional mutations in the MIRO2 gene do not have any visible impact on plant development, an insertional mutation in the MIRO1 gene is lethal during embryogenesis at the zygote to four-terminal-cell embryo stage. It also substantially impairs pollen germination and tube growth. Laser confocal and transmission electron microscopy revealed that the miro1 mutant pollen exhibits abnormally enlarged or tube-like mitochondrial morphology, leading to the disruption of continuous streaming of mitochondria in the growing pollen tube. Our findings suggest that mitochondrial morphology is influenced by MIRO1 and plays a vital role during embryogenesis and pollen tube growth.
authors.affiliation: Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.
authors.forename: Shohei
authors.initials: S
authors.lastname: Yamaoka
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Leaver
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D018525:Germination; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009154:Mutation; D011058:Pollen / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; C530348:EMB2473 protein, Arabidopsis; D020558:GTP Phosphohydrolases