Rice false smut, caused by Ustilaginoidea virens, is a devastating disease that greatly reduces rice yield and quality.  However, controlling rice false smut disease is challenging due to the unique infection mode of U. virens.  Therefore, there is a need for early diagnosis and monitoring techniques to prevent the spread of this disease.  Lateral flow strip-based recombinase polymerase amplification (LF-RPA) overcomes the limitations of current U. virens detection technologies, which are time-consuming, require delicate equipment, and have a high false-positive rate.  In this study, we used a comparative genomics approach to identify Uv_3611, a specific gene of U. virens, as the target for the LF-RPA assay.  The designed primers and probe efffectively detected the genomic DNA (gDNA) of U. virens and demonstrated no cross-reactivity with related pathogens.  Under optimal conditions, the LF-RPA assay demonstrated a sensitivity of 10 pg of U. virens gDNA.  Additionally, by incorporating a simplified PEG-NaOH method for plant DNA extraction, the LF-RPA assay enabled the detection of U. virens in rice spikelets within 30 min, without the need for specialized equipment.  Furthermore, the LF-RPA assay successfully detected U. virens in naturally infected rice and seed samples in the field.  Therefore, the LF-RPA assay is sensitive, efficient, and convenient, and could be developed as a kit for monitoring rice false smut disease in the field.

Fusarium head blight (FHB), mainly caused by fungus Fusarium graminearum (F. graminearum), is a devastating wheat disease worldwide, leading to reduced yield production and compromised grain quality due to contamination by mycotoxins, such as deoxynivalenol (DON). Manipulating the specific gene expression in microorganisms through RNA interference (RNAi) presents an opportunity for new-generation double-stranded RNA (dsRNA)-based formulations to combat a large number of plant diseases. Here, we applied both spray-induced gene silencing (SIGS) and host-induced gene silencing (HIGS) to target five virulence-related and DON-synthesized genes in F. graminearum, including protein kinase gene Gpmk1, zinc finger protein gene FgChy1, transcription factor FgSR, DON synthesis gene TRI5 and the cell-end marker protein gene FgTeaA, aiming to effectively control FHB in wheat. Direct spraying of individual or combined siRNAs (small interfering RNA) from the fungus showed reduced expression of target genes and suppressed pathogenic symptoms during F. graminearum infection in wheat leaves, with the combination of all five siRNAs demonstrating superior resistance. Furthermore, we generated transgenic wheat lines expressing chimeric RNAi cassettes targeting these five genes, and two independent lines exhibited strong resistance to FHB and Fusarium crown rot, and the reduced DON accumulation. Notably, the HIGS transgenic lines did not adversely impact plant growth and yield traits. Collectively, our findings support that SIGS and HIGS represent effective strategies targeting key pathogenic genes for bolstering disease resistance in crops.