A Cas12a-based platform combined with gold nanoparticles for sensitive and visual detection of Alternaria solani

Alternaria solani (A. solani), the causal agent of early blight in potatoes, poses a serious and persistent threat to potato production worldwide. Therefore, developing a method that can accurately detect A. solani in the early stage to avoid further spread is urgent. However, the conventional PCR-based method is not appropriate for application in the fields. Recently, the CRISPR-Cas system has been developed for nucleic acids analysis at point-of-care. Here, we propose a gold nanoparticles-based visual assay combining loop-mediated isothermal amplification with CRISPR-Cas12a to detect A. solani. After optimization, the method could detect 10^-3 ng/μL genomic gene of A. solani. The specificity of the method was confirmed by discriminating A. solani from other three highly homologous pathogens. We also developed a portable device that could be used in the fields. By integrating with the smartphone readout, this platform holds significant potential in high-throughput detection of multiple pathogens in the fields.