Poster: Organelle Biogenesis
Abs #
1130: Identification of the first plant gene involved in mitochondrial inheritance, distribution and morphology.
Mitochondria are ubiquitous and vital eukaryotic organelles. Although identified over 50 years ago as the site of oxidative energy metabolism, fundamental aspects of mitochondrial development and dynamics remain a mystery. We have initiated a novel research programme on the genes and mechanisms controlling higher plant mitochondrial shape, size, and number. Central to this work is the use of an Arabidopsis line in which GFP is targeted to the mitochondria (Logan & Leaver, 2000). Seed of this line were mutagenised and the M2 generation screened by fluorescence microscopy to identify individuals with an altered mitochondrial phenotype. We identified 7 novel mutants with discrete mitochondrial phenotypes. The friendly mitochondrial mutant (fmt) was identified by the presence of clusters of tens of mitochondria in all cell types examined, a phenotype similar to that in cluA- mutants of Dictyostelium discoideum. To identify the mutant gene we used a combination of forward and reverse genetics. Map-based cloning identified markers flanking a 3.9 cM region that contained the Arabidopsis CluA homologue. The DNA sequence of this gene contained a single point mutation at the boundary of the second intron thereby destroying the intron-exon boundary consensus sequence. Switching to a reverse genetics approach, plants containing T-DNA insertions in the Arabidopsis CluA homologue were transformed with mito-GFP and analysed by epifluoresence microscopy. Plants homozygous for the T-DNA insertion all displayed a fmt phenotype. Together, all of our data show that the Arabidopsis CluA homologue, FMT, is the first plant gene to be shown to be involved in mitochondrial inheritance, distribution and morphology. Logan DC and Leaver CJ (2000) J Ex Bot 51, 865-871.
