Combined Recombinase Polymerase Amplification CRISPR/Cas12a Assay for Detecting <em>Fusarium oxysporum</em> f. sp. <em>cubense</em> Tropical Race 4

Regular and accurate surveillance stands central to the efficient management of plant diseases. It can indicate which course of action is most appropriate, and whether prevention, eradication, or no action is required. Surveillance based on symptomology in host plants alone is often not reliable due to similarities in the symptoms caused by biotic and abiotic stresses. Laboratory-based molecular methods such as polymerase chain reaction (PCR) and quantitative (q)PCR are the most commonly and reliably used for plant pathogen detection, but rely on expensive equipment and skilled operators. Here, we describe a protocol combining a simplified DNA extraction, recombinase polymerase amplification (RPA), and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a (RPA-Cas12a) for the detection of the invasive pathogen, Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). The technique provides a simple single-tube detection alternative that is analytically robust with improved specificity compared to available molecular detection assays and negates the need for expensive and sophisticated laboratory equipment.