Pathogen detection and microbiome analysis of infected wheat using a portable DNA sequencer

Fungal diseases of plants are responsible for major losses in agriculture, highlighting the need for rapid and accurate identification of plant pathogens. Disease outcomes are often defined not only by the main pathogen but are influenced by diverse microbial communities known as the microbiome at sites of infection. Here we present the first use of whole genome shot-gun sequencing with a portable DNA sequencing device as a method for the detection of fungal pathogens from wheat (Triticum aestivum) in a standard molecular biology laboratory. The data revealed that our method is robust and applicable to the diagnosis of fungal diseases including wheat stripe rust (caused by Puccinia striiformis f. sp. tritici), Septoria tritici blotch (caused by Zymoseptoria tritici), and yellow leaf spot (caused by Pyrenophora tritici repentis). We also identified the bacterial genus Pseudomonas co-present with Puccinia and Zymoseptoria but not Pyrenophorainfections. One limitation of the method is the over-representation of redundant wheat genome sequences from samples. This could be addressed by long-range amplicon-based sequencing approaches in future studies, which specifically target non-host organisms. Our work outlines a new approach for detection of a broad range of plant pathogens and associated microbes using a portable sequencer in a standard laboratory, providing the basis for future development of an on-site disease monitoring system.