Quantitative detection of economically important Fusarium oxysporum f. sp. cubense strains in Africa in plants, soil and water

PLoS One. 2020 Jul 20;15(7):e0236110. doi: 10.1371/journal.pone.0236110. eCollection 2020.

Abstract

Banana is an important food crop and source of income in Africa. Sustainable production of banana, however, is at risk because of pests and diseases such as Fusarium wilt, caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc). Foc can be disseminated from infested to disease-free fields in plant material, water and soil. Early detection of Foc using DNA technologies is thus required to accurately identify the fungus and prevent its further dissemination with plants, soil and water. In this study, quantitative (q)PCR assays were developed for the detection of Foc Lineage VI strains found in central and eastern Africa (Foc races 1 and 2), Foc TR4 (vegetative compatibility groups (VCG) 01213/16) that is present in Mozambique, and Foc STR4 (VCG 0120/15) that occurs in South Africa. A collection of 127 fungal isolates were selected for specificity testing, including endophytic Fusarium isolates from banana pseudostems, non-pathogenic F. oxysporum strains and Foc isolates representing the 24 VCGs in Foc. Primer sets that proved to be specific to Foc Lineage VI, Foc TR4 and Foc STR4 were used to produce standard curves for absolute quantification, and the qPCR assays were evaluated based on the quality of standard curves, repeatability and reproducibility, and limits of quantification (LOQ) and detection (LOD). The qPCR assays for Foc Lineage VI, TR4 and STR4 were repeatable and reproducible, with LOQ values of 10-3-10-4 ng/μL and a LOD of 10-4-10-5 ng/μL. The quantitative detection of Foc strains in Africa could reduce the time and improve the accuracy for identifying the Fusarium wilt pathogen from plants, water and soil on the continent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa
  • Fusarium / genetics
  • Fusarium / isolation & purification*
  • Fusarium / physiology
  • Musa / microbiology*
  • Plant Diseases / microbiology
  • Polymerase Chain Reaction
  • Soil Microbiology*
  • Water Microbiology*

Grants and funding

AV received funding from the the International Institute of Tropical Agriculture (IITA) (ID: OPP1093845) through the project ‘Improvement of Banana for Smallholder Farmers in the Great Lakes Region of Africa’) (https://breedingbetterbananas.org/) and the Banana Industry Grant Facility channelled through the Ministério da Agricultura e Segurança Alimentar (MASA) to TechnoServe financed by the United States Department of Agriculture (USDA) (https://www.bananamoz.org/projects). DM received additional funding from the as National research foundation (NFR) of South Africa funding through early career Thuthuka research grant (ID: TTK180416321501) (https://www.nrf.ac.za). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.