title: Characterization of spermidine and spermine synthases in Lotus japonicus: induction and spatial organization of polyamine biosynthesis in nitrogen fixing nodules.
abstract: The biosynthesis of the polyamines spermidine (Spd) and spermine (Spm) from putrescine (Put) is catalysed by the consequent action of two aminopropyltransferases, spermidine synthase (SPDS EC: 2.5.1.16) and spermine synthase (SPMS EC: 2.5.1.22). Two cDNA clones coding for SPDS and SPMS homologues in the nitrogen-fixing nodules of the model legume Lotus japonicus were identified. Functionality of the encoded polypeptides was confirmed by their ability to complement spermidine and spermine deficiencies in yeast. The temporal and spatial expression pattern of the respective genes was correlated with the accumulation of total polyamines in symbiotic and non-symbiotic organs. Expression of both genes was maximal at early stages of nodule development, while at later stages the levels of both transcripts declined. Both genes were expressed in nodule inner cortical cells, vascular bundles, and central tissue. In contrast to gene expression, increasing amounts of Put, Spd, and Spm were found to accumulate during nodule development and after maturity. Interestingly, nodulated plants exhibited systemic changes in both LjSPDS and LjSPMS transcript levels and polyamine content in roots, stem and leaves, in comparison to uninoculated plants. These results give new insights into the neglected role of polyamines during nodule development and symbiotic nitrogen fixation (SNF).
authors.affiliation: Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, 118 55, Athens, Greece.
authors.forename: R C
authors.initials: RC
authors.lastname: Efrose
authors.forename: E
authors.initials: E
authors.lastname: Flemetakis
authors.forename: L
authors.initials: L
authors.lastname: Sfichi
authors.forename: C
authors.initials: C
authors.lastname: Stedel
authors.forename: E D
authors.initials: ED
authors.lastname: Kouri
authors.forename: M K
authors.initials: MK
authors.lastname: Udvardi
authors.forename: K
authors.initials: K
authors.lastname: Kotzabasis
authors.forename: P
authors.initials: P
authors.lastname: Katinakis
mesh_terms: D000595:Amino Acid Sequence; D005816:Genetic Complementation Test; D017403:In Situ Hybridization; D000070116:Lotus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053204:Root Nodules, Plant / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D011436:Spermidine Synthase / Q000235:genetics* / Q000378:metabolism; D013097:Spermine Synthase / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; D011073:Polyamines; D011436:Spermidine Synthase; D013097:Spermine Synthase