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G3 (Bethesda). 2017 Nov 6;7(11):3809-3820. doi: 10.1534/g3.117.300344.

Architecture and Distribution of Introns in Core Genes of Four Fusarium Species.

Author information

1
Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Faculty of Natural and Agricultural Sciences, University of Pretoria, 0002 South Africa.
2
Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Faculty of Natural and Agricultural Sciences, University of Pretoria, 0002 South Africa.
3
Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Faculty of Natural and Agricultural Sciences, University of Pretoria, 0002 South Africa emma.steenkamp@fabi.up.ac.za.

Abstract

Removal of introns from transcribed RNA represents a crucial step during the production of mRNA in eukaryotes. Available whole-genome sequences and expressed sequence tags (ESTs) have increased our knowledge of this process and revealed various commonalities among eukaryotes. However, certain aspects of intron structure and diversity are taxon-specific, which can complicate the accuracy of in silico gene prediction methods. Using core genes, we evaluated the distribution and architecture of Fusarium circinatum spliceosomal introns, and linked these characteristics to the accuracy of the predicted gene models of the genome of this fungus. We also evaluated intron distribution and architecture in F. verticillioides, F. oxysporum, and F. graminearum, and made comparisons with F. circinatum Results indicated that F. circinatum and the three other Fusarium species have canonical 5' and 3' splice sites, but with subtle differences that are apparently not shared with those of other fungal genera. The polypyrimidine tract of Fusarium introns was also found to be highly divergent among species and genes. Furthermore, the conserved adenosine nucleoside required during the first step of splicing is contained within unique branch site motifs in certain Fusarium introns. Data generated here show that introns of F. circinatum, as well as F. verticillioides, F. oxysporum, and F. graminearum, are characterized by a number of unique features such as the CTHAH and ACCAT motifs of the branch site. Incorporation of such information into genome annotation software will undoubtedly improve the accuracy of gene prediction methods used for Fusarium species and related fungi.

KEYWORDS:

Fusarium; cis-elements; gene prediction; intron splicing; spliceosomal introns

PMID:
28993438
PMCID:
PMC5677156
DOI:
10.1534/g3.117.300344
[Indexed for MEDLINE]
Free PMC Article

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