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      https://www.ias.ac.in/article/fulltext/jgen/093/02/0431-0442

    • Keywords

       

      microsatellite; evolution; transcriptome; selection; untranslated regions; Helianthus annuus.

    • Abstract

       

      The distribution of microsatellites in exons, and their association with gene ontology (GO) terms is explored to elucidate patterns of microsatellite evolution in the common sunflower, Helianthus annuus. The relative position, motif, size and level of impurity were estimated for each microsatellite in the unigene database available from the Compositae Genome Project (CGP), and statistical analyses were performed to determine if differences in microsatellite distributions and enrichment within certain GO terms were significant. There are more translated than untranslated microsatellites, implying that many bring about structural changes in proteins. However, the greatest density is observed within the UTRs, particularly 5′UTRs. Further, UTR microsatellites are purer and longer than coding region microsatellites. This suggests that UTR microsatellites are either younger and under more relaxed constraints, or that purifying selection limits impurities, and directional selection favours their expansion. GOs associated with response to various environmental stimuli including water deprivation and salt stress were significantly enriched with microsatellites. This may suggest that these GOs are more labile in plant genomes, or that selection has favoured the maintenance of microsatellites in these genes over others. This study shows that the distribution of transcribed microsatellites in H. annuus is nonrandom, the coding region microsatellites are under greater constraint compared to the UTR microsatellites, and that these sequences are enriched within genes that regulate plant responses to environmental stress and stimuli.

    • Author Affiliations

       

      Sreepriya Pramod1 Andy D. Perkins2 Mark E. Welch1

      1. Department of Biological Sciences, Mississippi State University, 219 Harned Hall, 295 Lee Boulevard, MS 39762, USA
      2. Department of Computer Science and Engineering, Mississippi State University, Butler Hall, MS 39762, USA
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