title: Large-scale analysis of gene expression profiles during early stages of root nodule formation in a model legume, Lotus japonicus.
abstract: Gene expression profiles during early stages of formation of symbiotic nitrogen-fixing nodules in a model legume Lotus japonicus were analyzed by means of a cDNA array of 18,144 non-redundant expressed sequence tags (ESTs) isolated from L. japonicus. Expression of a total of 1,076 genes was significantly accelerated during the successive stages that represent infection of Mesorhizobium loti, nodule primordium initiation, nodule organogenesis, and the onset of nitrogen fixation. These include 32 nodulin and nodulinhomolog genes as well as a number of genes involved in the catabolism of photosynthates and assimilation of fixed nitrogen that were previously known to be abundantly expressed in root nodules of many legumes. We also identified a large number of novel nodule-specific or enhanced genes, which include genes involved in many cellular processes such as membrane transport, defense responses, phytohormone synthesis and responses, signal transduction, cell wall synthesis, and transcriptional regulation. Notably, our data indicate that the gene expression profile in early steps of Rhizobium-legume interactions is considerably different from that in subsequent stages of nodule development. A number of genes involved in the defense responses to pathogens and other stresses were induced abundantly in the infection process, but their expression was suppressed during subsequent nodule formation. The results provide a comprehensive data source for investigation of molecular mechanisms underlying nodulation and symbiotic nitrogen fixation.
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan. kouchih@nias.affrc.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kouchi
authors.forename: Kenshiro
authors.initials: K
authors.lastname: Shimomura
authors.forename: Shingo
authors.initials: S
authors.lastname: Hata
authors.forename: Atsuko
authors.initials: A
authors.lastname: Hirota
authors.forename: Guo-Jiang
authors.initials: GJ
authors.lastname: Wu
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kumagai
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Tajima
authors.forename: Norio
authors.initials: N
authors.lastname: Suganuma
authors.forename: Akihiro
authors.initials: A
authors.lastname: Suzuki
authors.forename: Toshio
authors.initials: T
authors.lastname: Aoki
authors.forename: Makoto
authors.initials: M
authors.lastname: Hayashi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Takuji
authors.initials: T
authors.lastname: Ohyama
authors.forename: Erika
authors.initials: E
authors.lastname: Asamizu
authors.forename: Chikara
authors.initials: C
authors.lastname: Kuwata
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shibata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
mesh_terms: D015152:Blotting, Northern; D002473:Cell Wall / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005798:Genes, Bacterial; D000070116:Lotus / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D008565:Membrane Proteins / Q000235:genetics; D009586:Nitrogen Fixation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000096:biosynthesis; D010940:Plant Proteins / Q000235:genetics; D018517:Plant Roots / Q000378:metabolism; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000235:genetics; D012230:Rhizobiaceae / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics; D013559:Symbiosis; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D008565:Membrane Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; C045625:nodulin