title: Analysis of sequence, map position, and gene expression reveals conserved essential genes for iron uptake in Arabidopsis and tomato.
abstract: Arabidopsis (Arabidopsis thaliana) and tomato (Lycopersicon esculentum) show similar physiological responses to iron deficiency, suggesting that homologous genes are involved. Essential gene functions are generally considered to be carried out by orthologs that have remained conserved in sequence and map position in evolutionarily related species. This assumption has not yet been proven for plant genomes that underwent large genome rearrangements. We addressed this question in an attempt to deduce functional gene pairs for iron reduction, iron transport, and iron regulation between Arabidopsis and tomato. Iron uptake processes are essential for plant growth. We investigated iron uptake gene pairs from tomato and Arabidopsis, namely sequence, conserved gene content of the regions containing iron uptake homologs based on conserved orthologous set marker analysis, gene expression patterns, and, in two cases, genetic data. Compared to tomato, the Arabidopsis genome revealed more and larger gene families coding for the iron uptake functions. The number of possible homologous pairs was reduced if functional expression data were taken into account in addition to sequence and map position. We predict novel homologous as well as partially redundant functions of ferric reductase-like and iron-regulated transporter-like genes in Arabidopsis and tomato. Arabidopsis nicotianamine synthase genes encode a partially redundant family. In this study, Arabidopsis gene redundancy generally reflected the presumed genome duplication structure. In some cases, statistical analysis of conserved gene regions between tomato and Arabidopsis suggested a common evolutionary origin. Although involvement of conserved genes in iron uptake was found, these essential genes seem to be of paralogous rather than orthologous origin in tomato and Arabidopsis.
authors.affiliation: Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany. bauer@ipk-gatersleben.de
authors.forename: Petra
authors.initials: P
authors.lastname: Bauer
authors.forename: Thomas
authors.initials: T
authors.lastname: Thiel
authors.forename: Marco
authors.initials: M
authors.lastname: Klatte
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bereczky
authors.forename: Tzvetina
authors.initials: T
authors.lastname: Brumbarova
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hell
authors.forename: Ivo
authors.initials: I
authors.lastname: Grosse
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D017124:Conserved Sequence; D018506:Gene Expression Regulation, Plant; D005819:Genetic Markers; D007501:Iron / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins; D007501:Iron