Project description:RNA-seq analysis was performed to know the expression profiles of Lotus japonicus genes during nodule development and nitrogen fixation.
Project description:Legume plants can establish symbiotic nitrogen fixation (SNF) with rhizobia mostly in root nodules, where rhizobia-infected cells are accompanied with uninfected cells in a mosaic pattern. Inside the mature nodules of legume, carbon and nitrogen nutrients between host plant cells and their resident bacteria are actively exchanged. To elucidate the metabolite dynamics relevant for SNF in nodules, three cell-types from nodule tissues of a model legume, Lotus japonicus, were isolated using laser microdissesction, and transcriptome analysis was done by an oligoarray with 60-mer length representing 21,495 genes. In our cell-type-specific profiling, many genes were identified as being expressed in nodules with spatial-specific manners. Among them, genes coding for metabolic enzymes were classified according to their function, and detailed data analysis figured out that secondary metabolic pathway was highly activated in nodule cortex. In particular, a number of metabolic genes for phenyl propanoid pathway were found as highly expressed genes accompanied with those encoding putative transporters of secondary metabolites. These data suggest the involvement of novel physiological function of phenylpropanoids in SNF. Gene expression in three different cell-types of Lotus japonicus nodule was measured. Three independent experiments were performed at each cell-types.
Project description:Legumes interact with rhizobial bacteria to form nitrogen-fixing root nodules. Host signalling following mutual recognition ensures a specific response, but is only partially understood. Focusing on the stage of epidermal infection with Mesorhizobium loti, we analysed endogenous small RNAs (sRNAs) of the model legume Lotus japonicus to investigate their involvement in host response regulation. We used Illumina sequencing to annotate the L. japonicus sRNA-ome and isolate infection-responsive sRNAs, followed by candidate-based functional characterization. Sequences from four libraries revealed 219 novel L. japonicus micro RNAs (miRNAs) from 114 newly assigned families, and 76 infection-responsive sRNAs. Unlike infection-associated coding genes such as NODULE INCEPTION (NIN), a micro RNA 172 (miR172) isoform showed strong accumulation in dependency of both Nodulation (Nod) factor and compatible rhizobia. The genetics of miR172 induction support the existence of distinct epidermal and cortical signalling events. MIR172a promoter activity followed a previously unseen pattern preceding infection thread progression in epidermal and cortical cells. Nodule-associated miR172a expression was infection-independent, representing the second of two genetically separable activity waves. The combined data provide a valuable resource for further study, and identify miR172 as an sRNA marking successful epidermal infection. We show that miR172 acts upstream of several APETALA2-type (AP2) transcription factors, and suggest that it has a role in fine-tuning AP2 levels during bacterial symbiosis.
Project description:Acting in a partially redundant manner, NF-Ys were shown previously to regulate bacterial infection, including selection of a superior rhizobial strain, and to participate in mediating nodule structure formation. However, the exact mechanism(s) by which these transcriptional factors exert their symbiotic functions has remained elusive. Gene expression profiling for wild-type and Nuclear Factor YA (nf-ya)-A mutants in roots of Lotus japonicus were conducted 4 days after inoculation with Mesorhizobium loti in order to understand the interaction of NF-Ys and other genes in Lotus japonicus.
Project description:Lotus japonicus is a perennial legume with a small diploid genome that has been adopted as a model species for legume genetics and genomics. With the genome sequence as a backdrop (Sato et al. 2008), we have generated a gene expression atlas that provides a global view of gene expression in all major organ systems of this species, including nodule and seed development.
Project description:To identify the regulatory targets of the R2R3-Myb transcription factor, LjMyb14, the gene was constitutively over-expressed in Lotus japonicus under the Lotus ubiquitin promoter. The gene expression levels of three biological replicates of the Lotus japonicus (MG20) were averaged and compared to the the gene expression levels of three independent lines of Lotus japonicus japonicus constituitively over expressing LjMyb14 using the Lotus ubiquitin promoter.
Project description:To identify the regulatory targets of the R2R3-Myb transcription factor, LjMyb14, the gene was constitutively over-expressed in Lotus japonicus under the Lotus ubiquitin promoter.
Project description:Legume plants can establish symbiotic nitrogen fixation (SNF) with rhizobia mostly in root nodules, where rhizobia-infected cells are accompanied with uninfected cells in a mosaic pattern. Inside the mature nodules of legume, carbon and nitrogen nutrients between host plant cells and their resident bacteria are actively exchanged. To elucidate the metabolite dynamics relevant for SNF in nodules, three cell-types from nodule tissues of a model legume, Lotus japonicus, were isolated using laser microdissesction, and transcriptome analysis was done by an oligoarray with 60-mer length representing 21,495 genes. In our cell-type-specific profiling, many genes were identified as being expressed in nodules with spatial-specific manners. Among them, genes coding for metabolic enzymes were classified according to their function, and detailed data analysis figured out that secondary metabolic pathway was highly activated in nodule cortex. In particular, a number of metabolic genes for phenyl propanoid pathway were found as highly expressed genes accompanied with those encoding putative transporters of secondary metabolites. These data suggest the involvement of novel physiological function of phenylpropanoids in SNF.