The promise of molecular identification of fungi to overcome the global challenges in plant biosecurity

Abstract

Phytopathogenic fungi are a highly diverse group of eukaryotes with significant impact on natural ecosystems and cultivated lands, causing diseases on crops, ornamentals and forest trees. Historical outbreaks of invasive fungal pathogens on staple crops have caused severe food security threats to human populations. Therefore, accurate identification of pathogenic fungi has a great impact on global plant biosecurity and is considered to be crucial in this era of global exchange of horticultural products and plant germplasm. Although morphological features have traditionally been used in fungal identification, the past two decades have witnessed revolutionary changes with the implementation of DNA sequence data. The nuclear ribosomal internal transcribed spacer region (ITS), the standard fungal DNA barcode, is extensively used for a quick and often approximate identification. However, due to limitations of single DNA barcodes in fungal species discrimination and establishment of evolutionary relationships, multiple genomic loci have been utilized. The identification of fungi in plant biosecurity and quarantine practices are often based on morphology and tentative taxonomic assignments have increased the risk to regional and global plant biosecurity. This mini-review summarizes (1) the significance of precise naming of pathogenic fungi; (2) the incorporation of molecular data in the identification of emerging phytopathogens with a few examples; and (3) the need for paradigm shifts in global plant biosecurity practices. In addition, we urge the relevant agencies of the countries lacking organized plant biosecurity practices to recognize the need to confront the potential threats on their staple crops, ornamentals and forest trees and support appropriate research for DNA-aided identification and classification, and application of accurate names to high priority phytopathogens and emerging species. This will enable effective disease surveillance, prevent unnecessary trade restrictions for plantbased products and enhance biosecurity and quarantine efforts