Isolation and characterization of Lotus japonicus genes involved in iron and zinc homeostasis

Cristina Cvitanich, Winnie Jensen, Niels Sandal, Dorthe Bødkær Jensen, Hanne Busk, Søren Husted*, Jens Stougaard, and Erik Østergaard Jensen. Department of Molecular Biology. University of Aarhus. Denmark. *Department of Agricultural Sciences, The Royal Veterinary and Agricultural University, Denmark

The goal of this project is to find ways to improve the nutritional value of legumes by identifying genes and proteins important for iron and zinc regulation in the model legume Lotus japonicus.  Legumes are important staples in the developing world and are a major source of nutrients in many areas.  Legumes are frequently grown in soil with limited nutrient availability.
Plants use finely tuned mechanisms to regulate levels of iron and zinc in different tissues.  Several genes involved in iron and zinc homeostasis have been described in yeast, and a few orthologs have been studied in plants.  
We have used these sequences to search for L. japonicus ESTs and genomic loci that are likely to be involved in iron and zinc metabolism.  We have identified sequences corresponding to ferritin, ferric reductases, metal transport proteins of the ZIP family, cation transporters of the NRAMP family, and members of the yellow stripe family.  The expression of these genes is being studied.  
Furthermore, we are trying to map genes involved in metal homeostasis. We found significantly different levels of several micronutrients between Lotus filicaulis and L. japonicus Gifu. These differences will be used to map genes important for Fe, Zn, and Cu homeostasis using L. filicaulis x L. japonicus Gifu recombinant inbred lines.