title: Rice pseudomolecule-anchored cross-species DNA sequence alignments indicate regional genomic variation in expressed sequence conservation.
abstract: BACKGROUND
  Various methods have been developed to explore inter-genomic relationships among plant species. Here, we present a sequence similarity analysis based upon comparison of transcript-assembly and methylation-filtered databases from five plant species and physically anchored rice coding sequences.
  
  
  RESULTS
  A comparison of the frequency of sequence alignments, determined by MegaBLAST, between rice coding sequences in TIGR pseudomolecules and annotations vs 4.0 and comprehensive transcript-assembly and methylation-filtered databases from Lolium perenne (ryegrass), Zea mays (maize), Hordeum vulgare (barley), Glycine max (soybean) and Arabidopsis thaliana (thale cress) was undertaken. Each rice pseudomolecule was divided into 10 segments, each containing 10% of the functionally annotated, expressed genes. This indicated a correlation between relative segment position in the rice genome and numbers of alignments with all the queried monocot and dicot plant databases. Colour-coded moving windows of 100 functionally annotated, expressed genes along each pseudomolecule were used to generate 'heat-maps'. These revealed consistent intra- and inter-pseudomolecule variation in the relative concentrations of significant alignments with the tested plant databases. Analysis of the annotations and derived putative expression patterns of rice genes from 'hot-spots' and 'cold-spots' within the heat maps indicated possible functional differences. A similar comparison relating to ancestral duplications of the rice genome indicated that duplications were often associated with 'hot-spots'.
  
  
  CONCLUSIONS
  Physical positions of expressed genes in the rice genome are correlated with the degree of conservation of similar sequences in the transcriptomes of other plant species. This relative conservation is associated with the distribution of different sized gene families and segmentally duplicated loci and may have functional and evolutionary implications.
authors: Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK. ian.armstead@bbsrc.ac.uk
authors: Ian
authors: I
authors: Armstead
authors: Lin
authors: L
authors: Huang
authors: Julie
authors: J
authors: King
authors: Helen
authors: H
authors: Ougham
authors: Howard
authors: H
authors: Thomas
authors: Ian
authors: I
authors: King
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D017124:Conserved Sequence; D019175:DNA Methylation; D030541:Databases, Genetic; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D049810:Genetic Speciation; D014644:Genetic Variation; D018745:Genome, Plant; D001467:Hordeum / Q000235:genetics / Q000254:growth & development; D008129:Lolium / Q000235:genetics / Q000254:growth & development; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D010802:Phylogeny; D011544:Pseudogenes; D016415:Sequence Alignment / Q000379:methods*; D017422:Sequence Analysis, DNA / Q000379:methods; D012689:Sequence Homology, Nucleic Acid; D012984:Software; D013025:Glycine max / Q000235:genetics / Q000254:growth & development; D003313:Zea mays / Q000235:genetics / Q000254:growth & development
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