Project description:BACKGROUND: Legumes are the third largest family of flowering plants and are unique among crop species in their ability to fix atmospheric nitrogen. As a result of recent genome sequencing efforts, legumes are now one of a few plant families with extensive genomic and transcriptomic data available in multiple species. The unprecedented complexity and impending completeness of these data create opportunities for new approaches to discovery. RESULTS: We report here a transcriptional analysis in six different organ types of syntenic regions totaling approximately 1 Mb between the legume plants barrel medic (Medicago truncatula) and soybean (Glycine max) using oligonucleotide tiling microarrays. This analysis detected transcription of over 80% of the predicted genes in both species. We also identified 499 and 660 transcriptionally active regions from barrel medic and soybean, respectively, over half of which locate outside of the predicted exons. We used the tiling array data to detect differential gene expression in the six examined organ types and found several genes that are preferentially expressed in the nodule. Further investigation revealed that some collinear genes exhibit different expression patterns between the two species. CONCLUSION: These results demonstrate the utility of genome tiling microarrays in generating transcriptomic data to complement computational annotation of the newly available legume genome sequences. The tiling microarray data was further used to quantify gene expression levels in multiple organ types of two related legume species. Further development of this method should provide a new approach to comparative genomics aimed at elucidating genome organization and transcriptional regulation.
Project description:This SuperSeries is composed of the following subset Series: GSE10055: Transcriptional Analysis of 1M Regions in Medicago truncatula Using Tiling Microarrays GSE10056: Transcriptional Analysis of 1M Regions in Glycine max Using Tiling Microarrays Keywords: tiling array, transcriptional analysis Both the barrel medic and soybean tiling arrays were produced on the Maskless Array Synthesizer platform. Briefly, tiling-paths consisting of 36-mer oligonucleotides offset by five nucleotides were designed to represent both DNA strands of the selected barrel medic and soybean genome sequence. Probes were synthesized at a feature-density of 390,000 probes per array in a âchess boardâ design. Microarray production and storage were carried out. Total RNA and mRNA were sequentially isolated using the RNeasy Plant Mini kit (Qiagen, Valencia, CA) and the Oligotex mRNA kit (Qiagen) according to the manufacturerâs recommendations, respectively. mRNA from different organ types was reverse transcribed using a mixture of oligo(dT)18 and random nonamer primers, during which amino-allyl-modified dUTP (aa-dUTP) was incoporated. The aa-dUTP decorated cDNA was fluorescent labeled by conjugating the monofunctional Cy3 dye (GE Healthcare, Piscataway, NJ) to the amino-allyl functional groups in the cDNA. Two μg dye-labeled targets were used for hybridization.
Project description:We report here a transcriptonal analysis in six different organ types of a approximately 1 Mb region in soybean (Glycine max) which is sytenic with legume (Medicago truncatula). We used oligonucleotide tiling microarrays to detecte transcription of over 80% of the predicted genes in both species. We detected differential gene expression in the six examined organ types. Keywords: RNA
Project description:We report here a transcriptonal analysis in six different organ types of a approximately 1 Mb region in legume plants barrel medic (Medicago truncatula) which is sytenic with soybean (Glycine max). We used oligonucleotide tiling microarrays to detecte transcription of over 80% of the predicted genes in both species. We detected differential gene expression in the six examined organ types. Keywords: RNA
Project description:We report here a transcriptonal analysis in six different organ types of a approximately 1 Mb region in soybean (Glycine max) which is sytenic with legume (Medicago truncatula). We used oligonucleotide tiling microarrays to detecte transcription of over 80% of the predicted genes in both species. We detected differential gene expression in the six examined organ types. Keywords: RNA Both the barrel medic and soybean tiling arrays were produced on the Maskless Array Synthesizer platform. Briefly, tiling-paths consisting of 36-mer oligonucleotides offset by five nucleotides were designed to represent both DNA strands of the selected barrel medic and soybean genome sequence. Probes were synthesized at a feature-density of 390,000 probes per array in a âchess boardâ design. Microarray production and storage were carried out. Total RNA and mRNA were sequentially isolated using the RNeasy Plant Mini kit (Qiagen, Valencia, CA) and the Oligotex mRNA kit (Qiagen) according to the manufacturerâs recommendations, respectively. mRNA from different organ types was reverse transcribed using a mixture of oligo(dT)18 and random nonamer primers, during which amino-allyl-modified dUTP (aa-dUTP) was incoporated. The aa-dUTP decorated cDNA was fluorescent labeled by conjugating the monofunctional Cy3 dye (GE Healthcare, Piscataway, NJ) to the amino-allyl functional groups in the cDNA. Two μg dye-labeled targets were used for hybridization.
Project description:We report here a transcriptonal analysis in six different organ types of a approximately 1 Mb region in legume plants barrel medic (Medicago truncatula) which is sytenic with soybean (Glycine max). We used oligonucleotide tiling microarrays to detecte transcription of over 80% of the predicted genes in both species. We detected differential gene expression in the six examined organ types. Keywords: RNA Both the barrel medic and soybean tiling arrays were produced on the Maskless Array Synthesizer platform. Briefly, tiling-paths consisting of 36-mer oligonucleotides offset by five nucleotides were designed to represent both DNA strands of the selected barrel medic and soybean genome sequence. Probes were synthesized at a feature-density of 390,000 probes per array in a âchess boardâ design. Microarray production and storage were carried out. Total RNA and mRNA were sequentially isolated using the RNeasy Plant Mini kit (Qiagen, Valencia, CA) and the Oligotex mRNA kit (Qiagen) according to the manufacturerâs recommendations, respectively. mRNA from different organ types was reverse transcribed using a mixture of oligo(dT)18 and random nonamer primers, during which amino-allyl-modified dUTP (aa-dUTP) was incoporated. The aa-dUTP decorated cDNA was fluorescent labeled by conjugating the monofunctional Cy3 dye (GE Healthcare, Piscataway, NJ) to the amino-allyl functional groups in the cDNA. Two μg dye-labeled targets were used for hybridization.
Project description:BACKGROUND: Soybean lipoxygenases (Lxs) play important roles in plant resistance and in conferring the distinct bean flavor. Lxs comprise a multi-gene family that includes GmLx1, GmLx2 and GmLx3, and many of these genes have been characterized. We were interested in investigating the relationship between the soybean lipoxygenase isozymes from an evolutionary perspective, since soybean has undergone two rounds of polyploidy. Here we report the tetrad genome structure of soybean Lx regions produced by ancient and recent polyploidy. Also, comparative genomics with Medicago truncatula was performed to estimate Lxs in the common ancestor of soybean and Medicago. RESULTS: Two Lx regions in Medicago truncatula showing synteny with soybean were analyzed. Differential evolutionary rates between soybean and Medicago were observed and the median Ks values of Mt-Mt, Gm-Mt, and Gm-Gm paralogs were determined to be 0.75, 0.62, and 0.46, respectively. Thus the comparison of Gm-Mt paralogs (Ks = 0.62) and Gm-Mt orthologs (Ks = 0.45) supports the ancient duplication of Lx regions in the common ancestor prior to the Medicago-Glycine split. After speciation, no Lx regions generated by another polyploidy were identified in Medicago. Instead tandem duplication of Lx genes was observed. On the other hand, a lineage-specific duplication occurred in soybean resulting in two pairs of Lx regions. Each pair of soybean regions was co-orthologous to one Lx region in Medicago. A total of 34 Lx genes (15 MtLxs and 19 GmLxs) were divided into two groups by phylogenetic analysis. Our study shows that the Lx gene family evolved from two distinct Lx genes in the most recent common ancestor. CONCLUSION: This study analyzed two pairs of Lx regions generated by two rounds of polyploidy in soybean. Each pair of soybean homeologous regions is co-orthologous to one region of Medicago, demonstrating the quartet structure of the soybean genome. Differential evolutionary rates between soybean and Medicago were observed; thus optimized rates of Ks per year should be applied for accurate estimation of coalescence times to each case of comparison: soybean-soybean, soybean-Medicago, or Medicago-Medicago. In conclusion, the soybean Lx gene family expanded by ancient polyploidy prior to taxon divergence, followed by a soybean- specific duplication and tandem duplications, respectively.
Project description:Legume crops present important agronomical and environmental advantages mainly due to their capacity to reduce atmospheric N2 to ammonium via symbiotic nitrogen fixation (SNF). This process is very sensitive to abiotic stresses such as drought, but the mechanism underlying this response is not fully understood. The goal of the current work is to compare the drought response of two legumes with high economic impact and research importance, Medicago truncatula and Glycine max, by characterizing their root nodule proteomes. Our results show that, although M. truncatula exhibits lower water potential values under drought conditions compared to G. max, SNF declined analogously in the two legumes. Both of their nodule proteomes are very similar, and comparable down-regulation responses in the diverse protein functional groups were identified (mainly proteins related to the metabolism of carbon, nitrogen, and sulfur). We suggest lipoxygenases and protein turnover as newly recognized players in SNF regulation. Partial drought conditions applied to a split-root system resulted in the local down-regulation of the entire proteome of drought-stressed nodules in both legumes. The high degree of similarity between both legume proteomes suggests that the vast amount of research conducted on M. truncatula could be applied to economically important legume crops, such as soybean.
Project description:Processing of double-stranded RNA precursors into small RNAs is an essential regulator of gene expression in plant development and stress response. Small RNA processing requires the combined activity of a functionally diverse group of molecular components. However, in most of the plant species, there are insufficient mutant resources to functionally characterize each encoding gene. Here, mutations in loci encoding protein machinery involved in small RNA processing in soya bean and Medicago truncatula were generated using the CRISPR/Cas9 and TAL-effector nuclease (TALEN) mutagenesis platforms. An efficient CRISPR/Cas9 reagent was used to create a bi-allelic double mutant for the two soya bean paralogous Double-stranded RNA-binding2 (GmDrb2a and GmDrb2b) genes. These mutations, along with a CRISPR/Cas9-generated mutation of the M. truncatula Hua enhancer1 (MtHen1) gene, were determined to be germ-line transmissible. Furthermore, TALENs were used to generate a mutation within the soya bean Dicer-like2 gene. CRISPR/Cas9 mutagenesis of the soya bean Dicer-like3 gene and the GmHen1a gene was observed in the T0 generation, but these mutations failed to transmit to the T1 generation. The irregular transmission of induced mutations and the corresponding transgenes was investigated by whole-genome sequencing to reveal a spectrum of non-germ-line-targeted mutations and multiple transgene insertion events. Finally, a suite of combinatorial mutant plants were generated by combining the previously reported Gmdcl1a, Gmdcl1b and Gmdcl4b mutants with the Gmdrb2ab double mutant. Altogether, this study demonstrates the synergistic use of different genome engineering platforms to generate a collection of useful mutant plant lines for future study of small RNA processing in legume crops.
Project description:BACKGROUND: The root apical meristem of crop and model legume Medicago truncatula is a significantly different stem cell system to that of the widely studied model plant species Arabidopsis thaliana. In this study we used the Affymetrix Medicago GeneChip(R) to compare the transcriptomes of meristem and non-meristematic root to identify root meristem specific candidate genes. RESULTS: Using mRNA from root meristem and non-meristem we were able to identify 324 and 363 transcripts differentially expressed from the two regions. With bioinformatics tools developed to functionally annotate the Medicago genome array we could identify significant changes in metabolism, signalling and the differentially expression of 55 transcription factors in meristematic and non-meristematic roots. CONCLUSION: This is the first comprehensive analysis of M. truncatula root meristem cells using this genome array. This data will facilitate the mapping of regulatory and metabolic networks involved in the open root meristem of M. truncatula and provides candidates for functional analysis.