Project description:RNA-seq analysis was performed to know the expression profiles of Lotus japonicus genes during nodule development and nitrogen fixation.
Project description:Drought is one of the major environmental factors limiting biomass and seed yield production in agriculture. In this research we focused on plants from Fabaceae family, which have a unique ability for establishment of symbiosis with nitrogen-fixing bacteria, and are relatively susceptible to water limitation. We present the changes in nitrogenase activity and global gene expression occurring in Medicago truncatula and Lotus japonicus root nodules during water deficit. Our results prove a decrease in the efficiency of nitrogen fixation as well as extensive changes in plant and bacterial transcriptomes shortly after watering cessation. We show for the first time that not only symbiotic plant component, but also Sinorhizobium meliloti and Mesorhizobium loti bacteria residing in the root nodules of M. truncatula and L. japonicus, respectively, adjust their gene expression in response to water shortage. Although our results demonstrate that both M. truncatula and L. japonicus root nodules are susceptible to water deprivation, they indicate significant differences in plant and bacterial response to drought between tested species, which may be related to various type of root nodules formed by these species.
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: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:Lotus japonicus is a model legume broadly used to study transcriptome regulation under different stress conditions and microorganism interaction. Understanding how this model plant respond gainst alkaline stress will certainly help to develop more tolerant cultivars in economically important Lotus species as well as in other legumes. In order to uncover the most important response mechanisms activated during alkaline stress, we explored by microarray analysis the transcriptome regulation occurring in the phenotypically contrasting ecotypes MG-20 and Gifu B-129 of L. japonicus after 21 days of alkaline stress.
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: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.