This paper presents a novel in-field molecular diagnostic tool for crop diseases using a colorimetric paper and a smartphone. The tool enables multiplexed, low-cost, and rapid detection of crop pathogens via a nucleic acid amplification-free method combining toehold-mediated strand displacement with metal ion-mediated urease catalysis. The assay can distinguish viable and dead pathogens and identify fungicide-resistant isolates by detecting fungal RNA and mutations, providing crucial information for precision crop disease management. The entire sample-to-result process, including microneedle-based nucleic acid extraction and smartphone app analysis, takes approximately 10 minutes.

Ting Zhang, Qingdong Zeng, Fan Ji, Honghong Wu, Rodrigo Ledesma-Amaro, Qingshan Wei, Hao Yang, Xuhan Xia, Yao Ren, Keqing Mu, Qiang He, Zhensheng Kang, Ruijie Deng