Comparative genomics of geographically distant Fusarium fujikuroi isolates revealed two distinct pathotypes correlating with secondary metabolite profiles

PLoS Pathog. 2017 Oct 26;13(10):e1006670. doi: 10.1371/journal.ppat.1006670. eCollection 2017 Oct.

Abstract

Fusarium fujikuroi causes bakanae ("foolish seedling") disease of rice which is characterized by hyper-elongation of seedlings resulting from production of gibberellic acids (GAs) by the fungus. This plant pathogen is also known for production of harmful mycotoxins, such as fusarins, fusaric acid, apicidin F and beauvericin. Recently, we generated the first de novo genome sequence of F. fujikuroi strain IMI 58289 combined with extensive transcriptional, epigenetic, proteomic and chemical product analyses. GA production was shown to provide a selective advantage during infection of the preferred host plant rice. Here, we provide genome sequences of eight additional F. fujikuroi isolates from distant geographic regions. The isolates differ in the size of chromosomes, most likely due to variability of subtelomeric regions, the type of asexual spores (microconidia and/or macroconidia), and the number and expression of secondary metabolite gene clusters. Whilst most of the isolates caused the typical bakanae symptoms, one isolate, B14, caused stunting and early withering of infected seedlings. In contrast to the other isolates, B14 produced no GAs but high amounts of fumonisins during infection on rice. Furthermore, it differed from the other isolates by the presence of three additional polyketide synthase (PKS) genes (PKS40, PKS43, PKS51) and the absence of the F. fujikuroi-specific apicidin F (NRPS31) gene cluster. Analysis of additional field isolates confirmed the strong correlation between the pathotype (bakanae or stunting/withering), and the ability to produce either GAs or fumonisins. Deletion of the fumonisin and fusaric acid-specific PKS genes in B14 reduced the stunting/withering symptoms, whereas deletion of the PKS51 gene resulted in elevated symptom development. Phylogenetic analyses revealed two subclades of F. fujikuroi strains according to their pathotype and secondary metabolite profiles.

Publication types

  • Comparative Study

MeSH terms

  • Fungal Proteins / biosynthesis
  • Fusariosis / genetics
  • Fusarium / genetics*
  • Fusarium / metabolism
  • Fusarium / pathogenicity*
  • Genes, Fungal / genetics
  • Oryza / microbiology*
  • Phylogeny
  • Plant Diseases / microbiology*
  • Virulence

Substances

  • Fungal Proteins

Grants and funding

The study was supported by the Deutsche Forschungsgemainschaft (DFG), projects TU101/17-2 (BT); GU1205/2-2 (UG); HU730/9-3 (HUH). Furthermore, the work was supported by the Austrian Science Fund FWF, Special Research Project "Fusarium" F3705/DFGME1682/6-1 (UG) and by the grant from the Strategic Initiative for Microbiomes in Agriculture and Food, Ministry of Agriculture, Food and Rural Affairs, Republic of Korea and by the Soonchunhyang University Research Fund (NO: 20130591) (SHY). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.