Genetic relationships in the toxin-producing fungal endophyte, alternaria oxytropis using polyketide synthase and non-ribosomal peptide synthase genes

Rebecca Creamer, Deana Baucom Hille, Marwa Neyaz, Tesneem Nusayr, Christopher L. Schardl, Daniel Cook

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The legume Oxytropis sericea hosts a fungal endophyte, Alternaria oxytropis, which produces secondary metabolites (SM), including the toxin swainsonine. Polyketide synthase (PKS) and non-ribosomal peptide synthase (NRPS) enzymes are associated with biosynthesis of fungal SM. To better understand the origins of the SM, an unannotated genome of A. oxytropis was assessed for protein sequences similar to known PKS and NRPS enzymes of fungi. Contigs exhibiting identity with known genes were analyzed at nucleotide and protein levels using available databases. Software were used to identify PKS and NRPS domains and predict identity and function. Confirmation of sequence for selected gene sequences was accomplished using PCR. Thirteen PKS, 5 NRPS, and 4 PKS-NRPS hybrids were identified and characterized with functions including swainsonine and melanin biosynthesis. Phylogenetic relationships among closest amino acid matches with Alternaria spp. were identified for seven highly conserved PKS and NRPS, including melanin synthesis. Three PKS and NRPS were most closely related to other fungi within the Pleosporaceae family, while five PKS and PKS-NRPS were closely related to fungi in the Pleosporales order. However, seven PKS and PKS-NRPS showed no identity with fungi in the Pleosporales or the class Dothideomycetes, suggesting a different evolutionary origin for those genes.

Original languageEnglish
Article number538
JournalJournal of Fungi
Volume7
Issue number7
DOIs
StatePublished - Jul 2021

Bibliographical note

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Alternaria sect. Undifilum
  • Nonribosomal peptide synthase
  • Polyketide synthase
  • Secondary metabolite
  • Swainsonine biosynthesis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science
  • Microbiology (medical)

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