The distribution and type B trichothecene chemotype of Fusarium species associated with head blight of wheat in South Africa during 2008 and 2009

PLoS One. 2022 Sep 26;17(9):e0275084. doi: 10.1371/journal.pone.0275084. eCollection 2022.

Abstract

Fusarium head blight (FHB) of wheat occurs commonly in irrigation regions of South Africa and less frequently in dryland regions. Previous surveys of Fusarium species causing FHB identified isolates using morphological characters only. This study reports on a comprehensive characterisation of FHB pathogens conducted in 2008 and 2009. Symptomatic wheat heads were collected from the Northern Cape, KwaZulu-Natal (KZN), Bushveld and eastern Free State (irrigation regions), and from one field in the Western Cape (dryland region). Fusarium isolates were identified with species-specific primers or analysis of partial EF-1α sequences. A representative subset of isolates was characterized morphologically. In total, 1047 Fusarium isolates were collected, comprising 24 species from seven broad species complexes. The F. sambucinum (FSAMSC) and F. incarnatum-equiseti species complexes (FIESC) were most common (83.5% and 13.3% of isolates, respectively). The F. chlamydosporum (FCSC), F. fujikuroi (FFSC), F. oxysporum (FOSC), F. solani (FSSC), and F. tricinctum species complexes (FTSC) were also observed. Within the FSAMSC, 90.7% of isolates belonged to the F. graminearum species complex (FGSC), accounting for 75.7% of isolates. The FGSC was the dominant Fusaria in all four irrigation regions. F. pseudograminearum dominated at the dryland field in the Western Cape. The Northern Cape had the highest species diversity (16 Fusarium species from all seven species complexes). The type B trichothecene chemotype of FGSC and related species was inferred with PCR. Chemotype diversity was limited (15-ADON = 90.1%) and highly structured in relation to species differences. These results expand the known species diversity associated with FHB in South Africa and include first reports of F. acuminatum, F. armeniacum, F. avenaceum, F. temperatum, and F. pseudograminearum from wheat heads in South Africa, and of F. brachygibbosum, F. lunulosporum and F. transvaalense from wheat globally. Potentially novel species were identified within the FCSC, FFSC, FOSC, FSAMSC, FIESC and FTSC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fusarium* / genetics
  • Peptide Elongation Factor 1
  • Plant Diseases
  • South Africa
  • Trichothecenes
  • Trichothecenes, Type B*
  • Triticum

Substances

  • Peptide Elongation Factor 1
  • Trichothecenes
  • Trichothecenes, Type B
  • trichothecene

Grants and funding

This study was financially supported by the Western Cape Department of Agriculture (www.elsenburg.com), the Winter Cereal Trust (www.wintercerealtrust.co.za), the National Research Foundation (www.nrf.ac.za), and the United States Department of Agriculture - Agricultural Research Service National Program for Food Safety (www.usda.gov). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.