title: Transcriptome profiling of Lotus japonicus roots during arbuscular mycorrhiza development and comparison with that of nodulation.
abstract: To better understand the molecular responses of plants to arbuscular mycorrhizal (AM) fungi, we analyzed the differential gene expression patterns of Lotus japonicus, a model legume, with the aid of a large-scale cDNA macroarray. Experiments were carried out considering the effects of contaminating microorganisms in the soil inoculants. When the colonization by AM fungi, i.e. Glomus mosseae and Gigaspora margarita, was well established, four cysteine protease genes were induced. In situ hybridization revealed that these cysteine protease genes were specifically expressed in arbuscule-containing inner cortical cells of AM roots. On the other hand, phenylpropanoid biosynthesis-related genes for phenylalanine ammonia-lyase (PAL), chalcone synthase, etc. were repressed in the later stage, although they were moderately up-regulated on the initial association with the AM fungus. Real-time RT-PCR experiments supported the array experiments. To further confirm the characteristic expression, a PAL promoter was fused with a reporter gene and introduced into L. japonicus, and then the transformants were grown with a commercial inoculum of G. mosseae. The reporter activity was augmented throughout the roots due to the presence of contaminating microorganisms in the inoculum. Interestingly, G. mosseae only colonized where the reporter activity was low. Comparison of the transcriptome profiles of AM roots and nitrogen-fixing root nodules formed with Mesorhizobium loti indicated that the PAL genes and other phenylpropanoid biosynthesis-related genes were similarly repressed in the two organs.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Deguchi
authors.forename: Mari
authors.initials: M
authors.lastname: Banba
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Shimoda
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Chechetka
authors.forename: Ryota
authors.initials: R
authors.lastname: Suzuri
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Okusako
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ooki
authors.forename: Koichi
authors.initials: K
authors.lastname: Toyokura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Suzuki
authors.forename: Toshiki
authors.initials: T
authors.lastname: Uchiumi
authors.forename: Shiro
authors.initials: S
authors.lastname: Higashi
authors.forename: Mikiko
authors.initials: M
authors.lastname: Abe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kouchi
authors.forename: Katsura
authors.initials: K
authors.lastname: Izui
authors.forename: Shingo
authors.initials: S
authors.lastname: Hata
mesh_terms: D015536:Down-Regulation / Q000235:genetics; D005658:Fungi / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D000070116:Lotus / Q000235:genetics* / Q000382:microbiology; D038821:Mycorrhizae / Q000254:growth & development*; D009586:Nitrogen Fixation; D020411:Oligonucleotide Array Sequence Analysis; D018517:Plant Roots / Q000235:genetics* / Q000382:microbiology*; D053204:Root Nodules, Plant / Q000235:genetics* / Q000382:microbiology; D013559:Symbiosis; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics