Plant Genomics
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Genomic Signatures of Specialized Metabolism in Plants

Biswapriya Biswavas Misra's insight:

All plants synthesize basic metabolites needed for survival (primary metabolism), but different taxa produce distinct metabolites that are specialized for specific environmental interactions (specialized metabolism). Because evolutionary pressures on primary and specialized metabolism differ, we investigated differences in the emergence and maintenance of these processes across 16 species encompassing major plant lineages from algae to angiosperms. We found that, relative to their primary metabolic counterparts, genes coding for specialized metabolic functions have proliferated to a much greater degree and by different mechanisms and display lineage-specific patterns of physical clustering within the genome and coexpression. These properties illustrate the differential evolution of specialized metabolism in plants, and collectively they provide unique signatures for the potential discovery of novel specialized metabolic processes.

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Transcriptome differences between two sister desert poplar species under salt stress

Populus euphratica Oliv and P. pruinosa Schrenk (Salicaceae) both grow in dry desert areas with high summer temperatures. However, P. euphratica is distributed in dry deserts with deep underground water whereas P. pruinosa occurs in deserts in which there is underground water close to the surface. We therefore hypothesized that these two sister species may have evolved divergent regulatory and metabolic pathways during their interaction with different salt habitats and other stresses. To test this hypothesis, we compared transcriptomes from callus exposed to 24 h of salt stress and control callus samples from both species and identified differentially expressed genes (DEGs) and alternative splicing (AS) events that had occurred under salt stress.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Populus euphratica Oliv and P. pruinosa Schrenk (Salicaceae) both grow in dry desert areas with high summer temperatures. However, P. euphratica is distributed in dry deserts with deep underground water whereas P. pruinosa occurs in deserts in which there is underground water close to the surface. We therefore hypothesized that these two sister species may have evolved divergent regulatory and metabolic pathways during their interaction with different salt habitats and other stresses. To test this hypothesis, we compared transcriptomes from callus exposed to 24 h of salt stress and control callus samples from both species and identified differentially expressed genes (DEGs) and alternative splicing (AS) events that had occurred under salt stress.

Results

A total of 36,144 transcripts were identified and 1430 genes were found to be differentially expressed in at least one species in response to salt stress. Of these DEGs, 884 and 860 were identified in P. euphratica and P. pruinosa, respectively, while 314 DEGs were common to both species. On the basis of parametric analysis of gene set enrichment, GO enrichment in P. euphratica was found to be significantly different from that in P. pruinosa. Numerous genes involved in hormone biosynthesis, transporters and transcription factors showed clear differences between the two species in response to salt stress. We also identified 26,560 AS events which were mapped to 8380 poplar genomic loci from four libraries. GO enrichments for genes undergoing AS events in P. euphratica differed significantly from those in P. pruinosa.

Conclusions

A number of salt-responsive genes in both P. euphratica and P. pruinosa were identified and candidate genes with potential roles in the salinity adaptation were proposed. Transcriptome comparisons of two sister desert poplar species under salt stress suggest that these two species may have developed different genetic pathways in order to adapt to different desert salt habitats. The DEGs that were found to be common to both species under salt stress may be especially important for future genetic improvement of cultivated poplars or other crops through transgenic approaches in order to increase tolerance of saline soil conditions.

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DOE Joint Genome Institute - My submission for the DOE Joint Genome Institute Poetry…

DOE Joint Genome Institute - My submission for the DOE Joint Genome Institute Poetry… | Plant Genomics | Scoop.it

ENERGY IN THE TREES

Poplar tree growing fast and tall:
how do your genes make your cell walls?

Enzymes string together sugars into rows,
to make straight fibers you know as cellulose;

Reverse this process during cell wall degradation,
and you get sugars for biofuel creation!

Alas there’s also lignin, an amorphous beast;
lignin linked to cellulose blocks sugar release.

To solve this recalcitrance, the genome holds the key,
let’s make better poplar — for sustainable energy!


Via Francis Martin
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Francis Martin's curator insight, May 2, 2014 7:47 AM

Poem by Kelsey Wood was inspired in part by a talk by Gerald Tuskan (Oak Rigde) at JGI 2014 User's Meeting and is 10 lines long to mark a decade of the Community Science Program.

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The link between transcript regulation and de novo protein synthesis in the retrograde high light acclimation response of Arabidopsis thaliana

Efficient light acclimation of photosynthetic cells is a basic and important property of plants. The process of acclimation depends on transformation of retrograde signals in gene expression, transcript accumulation and de novo protein synthesis. While signalling cues, transcriptomes and some involved players have been characterized, an integrated view is only slowly emerging, and information on the translational level is missing. Transfer of low (8 mumol quanta.m-2.s-1) or normal light (80 mumol quanta.m-2.s-1) acclimated 30 d old Arabidopsis thaliana plants to high light (800 mumol quanta.m-2.s-1) triggers retrograde signals. Using this established approach, we sought to link transcriptome data with de novo synthesized proteins by in vivo labelling with 35S methionine and proteome composition.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Efficient light acclimation of photosynthetic cells is a basic and important property of plants. The process of acclimation depends on transformation of retrograde signals in gene expression, transcript accumulation and de novo protein synthesis. While signalling cues, transcriptomes and some involved players have been characterized, an integrated view is only slowly emerging, and information on the translational level is missing. Transfer of low (8 mumol quanta.m-2.s-1) or normal light (80 mumol quanta.m-2.s-1) acclimated 30 d old Arabidopsis thaliana plants to high light (800 mumol quanta.m-2.s-1) triggers retrograde signals. Using this established approach, we sought to link transcriptome data with de novo synthesized proteins by in vivo labelling with 35S methionine and proteome composition.

Results

De novo synthesized protein and proteome patterns could reliably be matched with newly annotated master gels. Each molecular level could be quantified for a set of 41 proteins. Among the proteins preferentially synthesized in plants transferred to high light were enzymes including carbonic anhydrase, fructose-1,6-bisphosphate aldolase, O-acetyl serine thiol lyase, and chaperones, while low rates upon transfer to high light were measured for e.g. dehydroascorbate reductase, glyceraldehyde-3-phosphate dehydrogenase and CuZn superoxide dismutase, and opposite responses between 10-fold and 100-fold light increment for e.g. glutamine synthetase and phosphoglycerate kinase.

Conclusions

The results prove the hypothesis that transcript abundance is poorly linked to de novo protein synthesis due to profound regulation at the level of translation. This vertical systems biology approach enables to quantitatively and kinetically link the molecular levels for scrutinizing signal processing and response generation.

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Single cell genome analysis of an uncultured heterotrophic stramenopile

Single cell genome analysis of an uncultured heterotrophic stramenopile | Plant Genomics | Scoop.it
A broad swath of eukaryotic microbial biodiversity cannot be cultivated in the lab and is therefore inaccessible to conventional genome-wide comparative methods. One promising approach to study these lineages is single cell genomics (SCG), whereby an individual cell is captured from nature and genome data are produced from the amplified total DNA. Here we tested the efficacy of SCG to generate a draft genome assembly from a single sample, in this case a cell belonging to the broadly distributed MAST-4 uncultured marine stramenopiles. Using de novo gene prediction, we identified 6,996 protein-encoding genes in the MAST-4 genome. This genetic inventory was sufficient to place the cell within the ToL using multigene phylogenetics and provided preliminary insights into the complex evolutionary history of horizontal gene transfer (HGT) in the MAST-4 lineage.
Biswapriya Biswavas Misra's insight:

A broad swath of eukaryotic microbial biodiversity cannot be cultivated in the lab and is therefore inaccessible to conventional genome-wide comparative methods. One promising approach to study these lineages is single cell genomics (SCG), whereby an individual cell is captured from nature and genome data are produced from the amplified total DNA. Here we tested the efficacy of SCG to generate a draft genome assembly from a single sample, in this case a cell belonging to the broadly distributed MAST-4 uncultured marine stramenopiles. Using de novo gene prediction, we identified 6,996 protein-encoding genes in the MAST-4 genome. This genetic inventory was sufficient to place the cell within the ToL using multigene phylogenetics and provided preliminary insights into the complex evolutionary history of horizontal gene transfer (HGT) in the MAST-4 lineage.

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High density SNP and SSR-based genetic maps of two independent oil palm hybrids

Oil palm is an important perennial oil crop with an extremely long selection cycle of 10 to 12 years. As such, any tool that speeds up its genetic improvement process, such as marker-assisted breeding is invaluable. Previously, genetic linkage maps based on AFLP, RFLP and SSR markers were developed and QTLs for fatty acid composition and yield components identified. High density genetic maps of crosses of different genetic backgrounds are indispensable tools for investigating oil palm genetics. They are also useful for comparative mapping analyses to identify markers closely linked to traits of interest.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Oil palm is an important perennial oil crop with an extremely long selection cycle of 10 to 12 years. As such, any tool that speeds up its genetic improvement process, such as marker-assisted breeding is invaluable. Previously, genetic linkage maps based on AFLP, RFLP and SSR markers were developed and QTLs for fatty acid composition and yield components identified. High density genetic maps of crosses of different genetic backgrounds are indispensable tools for investigating oil palm genetics. They are also useful for comparative mapping analyses to identify markers closely linked to traits of interest.

Results

A 4.5 K customized oil palm SNP array was developed using the Illumina Infinium platform. The SNPs and 252 SSRs were genotyped on two mapping populations, an intraspecific cross with 87 palms and an interspecific cross with 108 palms. Parental maps with 16 (LGs) linkage groups were constructed for the three fruit forms of E. guineensis (dura, pisifera and tenera). Map resolution was further increased by integrating the dura and pisifera maps into an intraspecific integrated map with 1,331 markers spanning 1,867 cM. We also report the first map of a Colombian E. oleifera, comprising 10 LGs with 65 markers spanning 471 cM. Although not very dense due to the high level of homozygosity in E. oleifera, the LGs were successfully integrated with the LGs of the tenera map. Direct comparison between the parental maps identified 603 transferable markers polymorphic in at least two of the parents. Further analysis revealed a high degree of marker transferability covering 1,075 cM, between the intra- and interspecific integrated maps. The interspecific cross displayed higher segregation distortion than the intraspecific cross. However, inclusion of distorted markers in the genetic maps did not disrupt the marker order and no map expansion was observed.

Conclusions

The high density SNP and SSR-based genetic maps reported in this paper have greatly improved marker density and genome coverage in comparison with the first reference map based on AFLP and SSR markers. Therefore, it is foreseen that they will be more useful for fine mapping of QTLs and whole genome association mapping studies in oil palm.

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shrikewolds's comment, June 30, 2015 1:37 AM
Very informative
cantatapledge's comment, July 3, 2015 6:33 AM

Its remarkable :)
Emilycanfield's comment, July 4, 2015 2:09 AM
Thats hip...
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PTRcombiner: mining combinatorial regulation of gene expression from post-transcriptional interaction maps

The progress in mapping RNA-protein and RNA-RNA interactions at the transcriptome-wide level paves the way to decipher possible combinatorial patterns embedded in post-transcriptional regulation of gene expression.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

The progress in mapping RNA-protein and RNA-RNA interactions at the transcriptome-wide level paves the way to decipher possible combinatorial patterns embedded in post-transcriptional regulation of gene expression.

Results

Here we propose an innovative computational tool to extract clusters of mRNA trans-acting co-regulators (RNA binding proteins and non-coding RNAs) from pairwise interaction annotations. In addition the tool allows to analyze the binding site similarity of co-regulators belonging to the same cluster, given their positional binding information. The tool has been tested on experimental collections of human and yeast interactions, identifying modules that coordinate functionally related messages.

Conclusions

This tool is an original attempt to uncover combinatorial patterns using all the post-transcriptional interaction data available so far. PTRcombiner is available at http://disi.unitn.it/~passerini/software/PTRcombiner/.

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The phenotypic predisposition of the parent in F1 hybrid is correlated with transcriptome preference of the positive general combining ability parent

Sprague and Tatum (1942) introduced the concepts of general combining ability (GCA) and specific combining ability (SCA) to evaluate the breeding parents and F1 hybrid performance, respectively. Since then, the GCA was widely used in cross breeding for elite parent selection. However, the molecular basis of GCA remains to unknown.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Sprague and Tatum (1942) introduced the concepts of general combining ability (GCA) and specific combining ability (SCA) to evaluate the breeding parents and F1 hybrid performance, respectively. Since then, the GCA was widely used in cross breeding for elite parent selection. However, the molecular basis of GCA remains to unknown.

Results

We studied the transcriptomes of three varieties and three F1 hybrids using RNA-Sequencing. Transcriptome sequence analysis revealed that the transcriptome profiles of the F1s were similar to the positive GCA-effect parent. Moreover, the expression levels of most differentially expressed genes (DEGs) were equal to the parent with a positive GCA effect. Analysis of the gene expression patterns of gibberellic acid (GA) and flowering time pathways that determine plant height and flowering time in rice validated the preferential transcriptome expression of the parents with positive GCA effect. Furthermore, H3K36me3 modification bias in the Pseudo-Response Regulators (PRR) gene family was observed in the positive GCA effect parents and demonstrated that the phenotype and transcriptome bias in the positive GCA effect parents have been epigenetically regulated by either global modification or specific signaling pathways in rice.

Conclusions

The results revealed that the transcriptome profiles and DEGs in the F1s were highly related to phenotype bias to the positive GCA-effect parent. The transcriptome bias toward high GCA parents in F1 hybrids attributed to H3K36me3 modification both on global modification level and specific signaling pathways. Our results indicated the transcriptome profile and epigenetic modification level bias to high GCA parents could be the molecular basis of GCA.

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Identification of a strawberry flavor gene candidate using an integrated genetic-genomic-analytical chemistry approach

There is interest in improving the flavor of commercial strawberry (Fragaria × ananassa) varieties. Fruit flavor is shaped by combinations of sugars, acids and volatile compounds. Many efforts seek to use genomics-based strategies to identify genes controlling flavor, and then designing durable molecular markers to follow these genes in breeding populations. In this report, fruit from two cultivars, varying for presence-absence of volatile compounds, along with segregating progeny, were analyzed using GC/MS and RNAseq. Expression data were bulked in silico according to presence/absence of a given volatile compound, in this case γ-decalactone, a compound conferring a peach flavor note to fruits.
Biswapriya Biswavas Misra's insight:
AbstractBackground

There is interest in improving the flavor of commercial strawberry (Fragaria × ananassa) varieties. Fruit flavor is shaped by combinations of sugars, acids and volatile compounds. Many efforts seek to use genomics-based strategies to identify genes controlling flavor, and then designing durable molecular markers to follow these genes in breeding populations. In this report, fruit from two cultivars, varying for presence-absence of volatile compounds, along with segregating progeny, were analyzed using GC/MS and RNAseq. Expression data were bulked in silico according to presence/absence of a given volatile compound, in this case γ-decalactone, a compound conferring a peach flavor note to fruits.

Results

Computationally sorting reads in segregating progeny based on γ-decalactone presence eliminated transcripts not directly relevant to the volatile, revealing transcripts possibly imparting quantitative contributions. One candidate encodes an omega-6 fatty acid desaturase, an enzyme known to participate in lactone production in fungi, noted here as FaFAD1. This candidate was induced by ripening, was detected in certain harvests, and correlated with γ-decalactone presence. The FaFAD1 gene is present in every genotype where γ-decalactone has been detected, and it was invariably missing in non-producers. A functional, PCR-based molecular marker was developed that cosegregates with the phenotype in F1 and BC1 populations, as well as in many other cultivars and wild Fragaria accessions.

Conclusions

Genetic, genomic and analytical chemistry techniques were combined to identify FaFAD1, a gene likely controlling a key flavor volatile in strawberry. The same data may now be re-sorted based on presence/absence of any other volatile to identify other flavor-affecting candidates, leading to rapid generation of gene-specific markers.

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Methods in Molecular Biology: Two-Dimensional Data Binning for the Analysis of Genome Architecture in Filamentous Plant Pathogens and Other Eukaryotes (2014)

Methods in Molecular Biology: Two-Dimensional Data Binning for the Analysis of Genome Architecture in Filamentous Plant Pathogens and Other Eukaryotes (2014) | Plant Genomics | Scoop.it

Genome architecture often reflects an organism’s lifestyle and can therefore provide insights into gene function, regulation, and adaptation. In several lineages of plant pathogenic fungi and oomycetes, characteristic repeat-rich and gene-sparse regions harbor pathogenicity-related genes such as effectors. In these pathogens, analysis of genome architecture has assisted the mining for novel candidate effector genes and investigations into patterns of gene regulation and evolution at the whole genome level. Here we describe a two-dimensional data binning method in R with a heatmap-style graphical output to facilitate analysis and visualization of whole genome architecture. The method is flexible, combining whole genome architecture heatmaps with scatter plots of the genomic environment of selected gene sets. This enables analysis of specific values associated with genes such as gene expression and sequence polymorphisms, according to genome architecture. This method enables the investigation of whole genome architecture and reveals local properties of genomic neighborhoods in a clear and concise manner.


Via Kamoun Lab @ TSL, The Sainsbury Lab, Liangjiao
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rougeforfire's curator insight, April 7, 2014 4:42 AM

This seems pretty interesting.. That's a nice gift idea

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The Diversity, Biogenesis, and Activities of Endogenous Silencing Small RNAs in Arabidopsis -

The Diversity, Biogenesis, and Activities of Endogenous Silencing Small RNAs in Arabidopsis - | Plant Genomics | Scoop.it
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Leaf Shape Evolution Through Duplication, Regulatory Diversification, and Loss of a Homeobox Gene

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Plant genome engineering in full bloom

Plant genome engineering in full bloom | Plant Genomics | Scoop.it
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The CRISPR/Cas9 system is a versatile tool for genome engineering.•A customizable gRNA and a nuclease are the core components of the CRISPR/Cas9 system.•The CRISPR/Cas9 system has been validated in Arabidopsis, tobacco, rice, wheat, and sorghum.•Researchers should be aware of potential off-target mutations when using the CRISPR/Cas9 system.

The recent development of tools for precise editing of user-specified sequences is rapidly changing the landscape for plant genetics and biotechnology. It is now possible to target mutations and regulatory proteins to specific sites in a genome using zinc-finger nucleases (ZFNs), transcription activator-like endonucleases (TALENs), or the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Here we provide an update of recent developments in CRISPR/Cas9 technology and highlight online resources that will help biologists adopt new genome-editing tools.

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Discovering Functions of Unannotated Genes from a Transcriptome Survey of Wild Fungal Isolates

Discovering Functions of Unannotated Genes from a Transcriptome Survey of Wild Fungal Isolates | Plant Genomics | Scoop.it

Most fungal genomes are poorly annotated, and many fungal traits of industrial and biomedical relevance are not well suited to classical genetic screens. Assigning genes to phenotypes on a genomic scale thus remains an urgent need in the field. We developed an approach to infer gene function from expression profiles of wild fungal isolates, and we applied our strategy to the filamentous fungus Neurospora crassa. Using transcriptome measurements in 70 strains from two well-defined clades of this microbe, we first identified 2,247 cases in which the expression of an unannotated gene rose and fell across N. crassa strains in parallel with the expression of well-characterized genes. We then used image analysis of hyphal morphologies, quantitative growth assays, and expression profiling to test the functions of four genes predicted from our population analyses. The results revealed two factors that influenced regulation of metabolism of nonpreferred carbon and nitrogen sources, a gene that governed hyphal architecture, and a gene that mediated amino acid starvation resistance. These findings validate the power of our population-transcriptomic approach for inference of novel gene function, and we suggest that this strategy will be of broad utility for genome-scale annotation in many fungal systems.


Via Francis Martin
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Widespread and frequent horizontal transfers of transposable elements in plants

Widespread and frequent horizontal transfers of transposable elements in plants | Plant Genomics | Scoop.it
An international, peer-reviewed genome sciences journal featuring outstanding original research that offers novel insights into the biology of all organisms
Biswapriya Biswavas Misra's insight:

Vertical, transgenerational transmission of genetic material occurs through reproduction of living organisms. In addition to vertical inheritance, horizontal gene transfer between reproductively isolated species has recently been shown to be an important, if not dominant, mechanism in the evolution of prokaryotic genomes. In contrast, only a few horizontal transfer (HT) events have been characterized so far in eukaryotes and mainly concern transposable elements (TEs). Whether these are frequent and have a significant impact on genome evolution remains largely unknown. We performed a computational search for highly conserved LTR retrotransposons among 40 sequenced eukaryotic genomes representing the major plant families. We found that 26 genomes (65%) harbor at least one case of horizontal TE transfer (HTT). These transfers concern species as distantly related as palm and grapevine, tomato and bean, or poplar and peach. In total, we identified 32 cases of HTTs, which could translate into more than 2 million among the 13,551 monocot and dicot genera. Moreover, we show that these TEs have remained functional after their transfer, occasionally causing a transpositional burst. This suggests that plants can frequently exchange genetic material through horizontal transfers and that this mechanism may be important in TE-driven genome evolution.

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Plant Genome -An Assessment of the Relative Inf...

Plant Genome -An Assessment of the Relative Inf... | Plant Genomics | Scoop.it
Andres Zurita's insight: While the greatest strength of systems biology may be to measure tens of thousands of variables across different genotypes, this simultaneously presents an enormous challenge to statistical analysis that cannot be...
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Comparative analysis of mitochondrial genomes between the hau cytoplasmic male sterility (CMS) line and its iso-nuclear maintainer line in Brassica juncea to reveal the or...

Cytoplasmic male sterility (CMS) is not only important for exploiting heterosis in crop plants, but also as a model for investigating nuclear-cytoplasmic interaction. CMS may be caused by mutations, rearrangement or recombination in the mitochondrial genome. Understanding the mitochondrial genome is often the first and key step in unraveling the molecular and genetic basis of CMS in plants. Comparative analysis of the mitochondrial genome of the hau CMS line and its maintainer line in B. juneca (Brassica juncea) may help show the origin of the CMS-associated gene orf288.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Cytoplasmic male sterility (CMS) is not only important for exploiting heterosis in crop plants, but also as a model for investigating nuclear-cytoplasmic interaction. CMS may be caused by mutations, rearrangement or recombination in the mitochondrial genome. Understanding the mitochondrial genome is often the first and key step in unraveling the molecular and genetic basis of CMS in plants. Comparative analysis of the mitochondrial genome of the hau CMS line and its maintainer line in B. juneca (Brassica juncea) may help show the origin of the CMS-associated gene orf288.

Results

Through next-generation sequencing, the B. juncea hau CMS mitochondrial genome was assembled into a single, circular-mapping molecule that is 247,903 bp in size and 45.08% in GC content. In addition to the CMS associated gene orf288, the genome contains 35 protein-encoding genes, 3 rRNAs, 25 tRNA genes and 29 ORFs of unknown function. The mitochondrial genome sizes of the maintainer line and another normal type line "J163-4" are both 219,863 bp and with GC content at 45.23%. The maintainer line has 36 genes with protein products, 3 rRNAs, 22 tRNA genes and 31 unidentified ORFs. Comparative analysis the mitochondrial genomes of the hau CMS line and its maintainer line allowed us to develop specific markers to separate the two lines at the seedling stage. We also confirmed that different mitotypes coexist substoichiometrically in hau CMS lines and its maintainer lines in B. juncea. The number of repeats larger than 100 bp in the hau CMS line (16 repeats) are nearly twice of those found in the maintainer line (9 repeats). Phylogenetic analysis of the CMS-associated gene orf288 and four other homologous sequences in Brassicaceae show that orf288 was clearly different from orf263 in Brassica tournefortii despite of strong similarity.

Conclusion

The hau CMS mitochondrial genome was highly rearranged when compared with its iso-nuclear maintainer line mitochondrial genome. This study may be useful for studying the mechanism of natural CMS in B. juncea, performing comparative analysis on sequenced mitochondrial genomes in Brassicas, and uncovering the origin of the hau CMS mitotype and structural and evolutionary differences between different mitotypes.

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An improved genome release (version Mt4.0) for the model legume Medicago truncatula

Medicago truncatula, a close relative of alfalfa, is a preeminent model for studying nitrogen fixation, symbiosis, and legume genomics. The Medicago sequencing project began in 2003 with the goal to decipher sequences originated from the euchromatic portion of the genome. The initial sequencing approach was based on a BAC tiling path, culminating in a BAC-based assembly (Mt3.5) as well as an in-depth analysis of the genome published in 2011.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Medicago truncatula, a close relative of alfalfa, is a preeminent model for studying nitrogen fixation, symbiosis, and legume genomics. The Medicago sequencing project began in 2003 with the goal to decipher sequences originated from the euchromatic portion of the genome. The initial sequencing approach was based on a BAC tiling path, culminating in a BAC-based assembly (Mt3.5) as well as an in-depth analysis of the genome published in 2011.

Results

Here we describe a further improved and refined version of the M. truncatula genome (Mt4.0) based on de novo whole genome shotgun assembly of a majority of Illumina and 454 reads using ALLPATHS-LG. The ALLPATHS-LG scaffolds were anchored onto the pseudomolecules on the basis of alignments to both the optical map and the genotyping-by-sequencing (GBS) map. The Mt4.0 pseudomolecules encompass ~360 Mb of actual sequences spanning 390 Mb of which ~330 Mb align perfectly with the optical map, presenting a drastic improvement over the BAC-based Mt3.5 which only contained 70% sequences (~250 Mb) of the current version. Most of the sequences and genes that previously resided on the unanchored portion of Mt3.5 have now been incorporated into the Mt4.0 pseudomolecules, with the exception of ~28 Mb of unplaced sequences. With regard to gene annotation, the genome has been re-annotated through our gene prediction pipeline, which integrates EST, RNA-seq, protein and gene prediction evidences. A total of 50,894 genes (31,661 high confidence and 19,233 low confidence) are included in Mt4.0 which overlapped with ~82% of the gene loci annotated in Mt3.5. Of the remaining genes, 14% of the Mt3.5 genes have been deprecated to an "unsupported" status and 4% are absent from the Mt4.0 predictions.

Conclusions

Mt4.0 and its associated resources, such as genome browsers, BLAST-able datasets and gene information pages, can be found on the JCVI Medicago web site (http://www.jcvi.org/medicago). The assembly and annotation has been deposited in GenBank (BioProject: PRJNA10791). The heavily curated chromosomal sequences and associated gene models of Medicago will serve as a better reference for legume biology and comparative genomics.

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De novo genome assembly of the soil-borne fungus and tomato pathogen Pyrenochaeta lycopersici

Pyrenochaeta lycopersici is a soil-dwelling ascomycete pathogen that causes corky root rot disease in tomato (Solanum lycopersicum) and other Solanaceous crops, reducing fruit yields by up to 75%. Fungal pathogens that infect roots receive less attention than those infecting the aerial parts of crops despite their significant impact on plant growth and fruit production.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Pyrenochaeta lycopersici is a soil-dwelling ascomycete pathogen that causes corky root rot disease in tomato (Solanum lycopersicum) and other Solanaceous crops, reducing fruit yields by up to 75%. Fungal pathogens that infect roots receive less attention than those infecting the aerial parts of crops despite their significant impact on plant growth and fruit production.

Results

We assembled a 54.9Mb P. lycopersici draft genome sequence based on Illumina short reads, and annotated approximately 17,000 genes. The P. lycopersici genome is closely related to hemibiotrophs and necrotrophs, in agreement with the phenotypic characteristics of the fungus and its lifestyle. Several gene families related to host-pathogen interactions are strongly represented, including those responsible for nutrient absorption, the detoxification of fungicides and plant cell wall degradation, the latter confirming that much of the genome is devoted to the pathogenic activity of the fungus. We did not find a MAT gene, which is consistent with the classification of P. lycopersici as an imperfect fungus, but we observed a significant expansion of the gene families associated with heterokaryon incompatibility (HI).

Conclusions

The P. lycopersici draft genome sequence provided insight into the molecular and genetic basis of the fungal lifestyle, characterizing previously unknown pathogenic behaviors and defining strategies that allow this asexual fungus to increase genetic diversity and to acquire new pathogenic traits.

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Identification and characterization of transcript polymorphisms in soybean lines varying in oil composition and content

Variation in seed oil composition and content among soybean varieties is largely attributed to differences in transcript sequences and/or transcript accumulation of oil production related genes in seeds. Discovery and analysis of sequence and expression variations in these genes will accelerate soybean oil quality improvement.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Variation in seed oil composition and content among soybean varieties is largely attributed to differences in transcript sequences and/or transcript accumulation of oil production related genes in seeds. Discovery and analysis of sequence and expression variations in these genes will accelerate soybean oil quality improvement.

Results

In an effort to identify these variations, we sequenced the transcriptomes of soybean seeds from nine lines varying in oil composition and/or total oil content. Our results showed that 69,338 distinct transcripts from 32,885 annotated genes were expressed in seeds. A total of 8,037 transcript expression polymorphisms and 50,485 transcript sequence polymorphisms (48,792 SNPs and 1,693 small Indels) were identified among the lines. Effects of the transcript polymorphisms on their encoded protein sequences and functions were predicted. The studies also provided independent evidence that the lack of FAD2-1A gene activity and a non-synonymous SNP in the coding sequence of FAB2C caused elevated oleic acid and stearic acid levels in soybean lines M23 and FAM94-41, respectively.

Conclusions

As a proof-of-concept, we developed an integrated RNA-seq and bioinformatics approach to identify and functionally annotate transcript polymorphisms, and demonstrated its high effectiveness for discovery of genetic and transcript variations that result in altered oil quality traits. The collection of transcript polymorphisms coupled with their predicted functional effects will be a valuable asset for further discovery of genes, gene variants, and functional markers to improve soybean oil quality.

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Genome sequence and transcriptome analyses of the thermophilic zygomycete fungus Rhizomucor miehei

The zygomycete fungi like Rhizomucor miehei have been extensively exploited for the production of various enzymes. As a thermophilic fungus, R. miehei is capable of growing at temperatures that approach the upper limits for all eukaryotes. To date, over hundreds of fungal genomes are publicly available. However, Zygomycetes have been rarely investigated both genetically and genomically.
Biswapriya Biswavas Misra's insight:
AbstractBackground

The zygomycete fungi like Rhizomucor miehei have been extensively exploited for the production of various enzymes. As a thermophilic fungus, R. miehei is capable of growing at temperatures that approach the upper limits for all eukaryotes. To date, over hundreds of fungal genomes are publicly available. However, Zygomycetes have been rarely investigated both genetically and genomically.

Results

Here, we report the genome of R. miehei CAU432 to explore the thermostable enzymatic repertoire of this fungus. The assembled genome size is 27.6-million-base (Mb) with 10,345 predicted protein-coding genes. Even being thermophilic, the G + C contents of fungal whole genome (43.8%) and coding genes (47.4%) are less than 50%. Phylogenetically, R. miehei is more closerly related to Phycomyces blakesleeanus than to Mucor circinelloides and Rhizopus oryzae. The genome of R. miehei harbors a large number of genes encoding secreted proteases, which is consistent with the characteristics of R. miehei being a rich producer of proteases. The transcriptome profile of R. miehei showed that the genes responsible for degrading starch, glucan, protein and lipid were highly expressed.

Conclusions

The genome information of R. miehei will facilitate future studies to better understand the mechanisms of fungal thermophilic adaptation and the exploring of the potential of R. miehei in industrial-scale production of thermostable enzymes. Based on the existence of a large repertoire of amylolytic, proteolytic and lipolytic genes in the genome, R. miehei has potential in the production of a variety of such enzymes.

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Discovering Functions of Unannotated Genes from a Transcriptome Survey of Wild Fungal Isolates

Discovering Functions of Unannotated Genes from a Transcriptome Survey of Wild Fungal Isolates | Plant Genomics | Scoop.it

Most fungal genomes are poorly annotated, and many fungal traits of industrial and biomedical relevance are not well suited to classical genetic screens. Assigning genes to phenotypes on a genomic scale thus remains an urgent need in the field. We developed an approach to infer gene function from expression profiles of wild fungal isolates, and we applied our strategy to the filamentous fungus Neurospora crassa. Using transcriptome measurements in 70 strains from two well-defined clades of this microbe, we first identified 2,247 cases in which the expression of an unannotated gene rose and fell across N. crassa strains in parallel with the expression of well-characterized genes. We then used image analysis of hyphal morphologies, quantitative growth assays, and expression profiling to test the functions of four genes predicted from our population analyses. The results revealed two factors that influenced regulation of metabolism of nonpreferred carbon and nitrogen sources, a gene that governed hyphal architecture, and a gene that mediated amino acid starvation resistance. These findings validate the power of our population-transcriptomic approach for inference of novel gene function, and we suggest that this strategy will be of broad utility for genome-scale annotation in many fungal systems.


Via Bradford Condon, Jie Wang
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The contrasting effects of genome size, chromosome number and ploidy level on plant invasiveness: a global analysis

The contrasting effects of genome size, chromosome number and ploidy level on plant invasiveness: a global analysis | Plant Genomics | Scoop.it
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Understanding how species' traits relate to their status (e.g. invasiveness or rarity) is important because it can help to efficiently focus conservation and management effort and infer mechanisms affecting plant status. This is particularly important for invasiveness, in which proactive action is needed to restrict the establishment of potentially invasive plants.We tested the ability of genome size (DNA 1C-values) to explain invasiveness and compared it with cytogenetic traits (chromosome number and ploidy level). We considered 890 species from 62 genera, from across the angiosperm phylogeny and distributed from tropical to boreal latitudes.We show that invasiveness was negatively related to genome size and positively related to chromosome number (and ploidy level), yet there was a positive relationship between genome size and chromosome number; that is, our result was not caused by collinearity between the traits. Including both traits in explanatory models greatly increased the explanatory power of each.This demonstrates the potential unifying role that genome size, chromosome number and ploidy have as species' traits, despite the diverse impacts they have on plant physiology. It provides support for the continued cataloguing of cytogenetic traits and genome size of the world's flora.

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The genome and life-stage specific transcriptomes of Globodera pallida elucidate key aspects of plant parasitism by a cyst nematode

Globodera pallida is a devastating pathogen of potato crops, making it one of the most economically important plant parasitic nematodes. It is also an important model for the biology of cyst nematodes. Cyst nematodes and root-knot nematodes are the two most important plant parasitic nematode groups and together represent a global threat to food security.
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Direct measurement of transcription rates reveals multiple mechanisms for configuration of the Arabidopsis ambient temperature response

Sensing and responding to ambient temperature is important for controlling growth and development of many organisms, in part by regulating mRNA levels. mRNA abundance can change with temperature, but it is unclear whether this results from changes in transcription or decay rates, and whether passive or active temperature regulation is involved.
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