Analysis of putative mitoferrins in Arabidopsis

Iron has a major role in mitochondrial activity; the processes of iron transport, trafficking and homeostasis in plant mitochondria are however mostly unknown. To identify key genes involved in iron transport into Arabidopsis mitochondria, we searched for genes with high homology with the Danio rerio (zebrafish) mitoferrin2 (Mfrn-2) coding for a mitochondrial iron transporter. We focused our interest on two genes, which we named MFL1 (MitoFerrinLike1) and MFL2 (MitoFerrinLike2), both sharing high homology with Mfrn-2. According to prediction (TMHMM Server v. 2.0, CBS Prediction Servers) both MFL1 and MFL2 possess three transmembrane domains; also, according to Arabidopsis eFP Browser, their expression is mainly localized in adult rosette leaves. Correlation analysis is a powerful tool to examine gene function and to identify candidate genes for specific processes; results of such analysis for MLF1 and MLF2 will be given. We isolated two independent KO mutant lines for each of the two genes (from Salk collection of Arabidopsis insertional mutants). Physiological characterization of such mutant lines is in progress and first ionomic results show that mfl1-1 and mfl1-2 (both KO for MFL1) have a higher Cd content in leaves. Both single mutants apparently do not show any growth defects; it is however known that, in S. cerevisiae, only mutations in both the iron carriers MRS3 and MRS4 alter growth [5] and indeed mrs3mrs4 yeast mutant strain has a “petite” phenotype under iron limiting conditions; for this reason the isolation of the double mfl1/mfl2 Arabidopsis mutant is in progress.