21 research outputs found

    A composite transcriptional signature differentiates responses towards closely related herbicides in Arabidopsis thaliana and Brassica napus

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    In this study, genome-wide expression profiling based on Affymetrix ATH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five herbicides, which contain active ingredients targeting two different branches of amino acid biosynthesis. One herbicide contained glyphosate, which targets 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), while the other four herbicides contain different acetolactate synthase (ALS) inhibiting compounds. In contrast to the herbicide containing glyphosate, which affected only a few transcripts, many effects of the ALS inhibiting herbicides were revealed based on transcriptional changes related to ribosome biogenesis and translation, secondary metabolism, cell wall modification and growth. The expression pattern of a set of 101 genes provided a specific, composite signature that was distinct from other major stress responses and differentiated among herbicides targeting the same enzyme (ALS) or containing the same chemical class of active ingredient (sulfonylurea). A set of homologous genes could be identified in Brassica napus that exhibited a similar expression pattern and correctly distinguished exposure to the five herbicides. Our results show the ability of a limited number of genes to classify and differentiate responses to closely related herbicides in A. thaliana and B. napus and the transferability of a complex transcriptional signature across species

    Separate introns gained within short and long soluble peridinin-chlorophyll a-protein genes during radiation of Symbiodinium (Dinophyceae) clade A and B lineages.

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    Here we document introns in two Symbiodinium clades that were most likely gained following divergence of this genus from other peridinin-containing dinoflagellate lineages. Soluble peridinin-chlorophyll a-proteins (sPCP) occur in short and long forms in different species. Duplication and fusion of short sPCP genes produced long sPCP genes. All short and long sPCP genes characterized to date, including those from free living species and Symbiodinium sp. 203 (clade C/type C2) are intronless. However, we observed that long sPCP genes from two Caribbean Symbiodinium clade B isolates each contained two introns. To test the hypothesis that introns were gained during radiation of clade B, we compared sPCP genomic and cDNA sequences from 13 additional distinct Caribbean and Pacific Symbiodinium clade A, B, and F isolates. Long sPCP genes from all clade B/B1 and B/B19 descendants contain orthologs of both introns. Short sPCP genes from S. pilosum (A/A2) and S. muscatinei (B/B4) plus long sPCP genes from S. microadriaticum (A/A1) and S. kawagutii (F/F1) are intronless. Short sPCP genes of S. microadriaticum have a third unique intron. Symbiodinium clade B long sPCP sequences are useful for assessing divergence among B1 and B19 descendants. Phylogenetic analyses of coding sequences from four dinoflagellate orders indicate that introns were gained independently during radiation of Symbiodinium clades A and B. Long sPCP introns were present in the most recent common ancestor of Symbiodinium clade B core types B1 and B19, which apparently diverged sometime during the Miocene. The clade A short sPCP intron was either gained by S. microadriaticum or possibly by the ancestor of Symbiodinium types A/A1, A3, A4 and A5. The timing of short sPCP intron gain in Symbiodinium clade A is less certain. But, all sPCP introns were gained after fusion of ancestral short sPCP genes, which we confirm as occurring once in dinoflagellate evolution

    Maps showing the organization of <i>Symbiodinium sPCP</i> tandem genes containing introns and the corresponding cDNAs.

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    <p>(A) Long <i>sPCP</i> genes from clade B/B1 and B19 descendant isolates contained two introns. The CDS identified in genomic and cDNA clones was ∼1.1 kb. (B) Short <i>sPCP</i> genes from <i>S. microadriaticum</i> (clade A/A1) had one intron and the CDS was ∼600 bp.</p

    Sizes of <i>Symbiodinium sPCP</i> exons, introns, genomic CDS and cDNA CDS (bp).

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    <p>Sizes of <i>Symbiodinium sPCP</i> exons, introns, genomic CDS and cDNA CDS (bp).</p

    Average pair-wise distances of <i>Symbiodinium</i> Clade B nuclear ITS1-5.8S-ITS2, CA4.86, Si15 and long <i>sPCP</i> sequences.

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    <p>Average pair-wise distances of <i>Symbiodinium</i> Clade B nuclear ITS1-5.8S-ITS2, CA4.86, Si15 and long <i>sPCP</i> sequences.</p

    Phylogenies of long and short <i>sPCP</i> coding sequences (excluding introns) from four dinoflagellate orders.

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    <p>(A) Most parsimonious tree for long <i>sPCP</i> CDS data from the Suessiales, Gonyaulacales and Gynnodiniales. (B) Most parsimonious tree for short <i>sPCP</i> CDS from the Suessiales and Peridiniales. Branch lengths are shown above the branches. Support values >50% based on +1000 bootstrap trees are shown in parentheses below branches. Double inverted triangles = the long <i>sPCP</i> branch leading to <i>Symbiodinium</i> clade B sequences, each of which contained two introns. Single inverted triangle = the short <i>sPCP</i> branch for the <i>S. microadriaticum</i> sequence that had a single intron. (C) Long <i>sPCP</i> tree redrawn to indicate possibility of ancient introns present in the most recent common ancestor of Suessiales, Gonyaulacales and Gynnodiniales. Vertical bar<b> = </b>loss of an intron on an ascending branch required to explain the data. (D) Short <i>sPCP</i> tree redrawn to indicate possibility of an ancient intron present in the most recent common ancestor of Suessiales and Peridinales. Required losses on ascending branches are indicated as before.</p
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