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Updated: Jun 24, 2026
On-Site Molecular Detection of Soil-Borne Phytopathogens Using a Portable Real-Time PCR System
Published on: February 23, 2018
Smartphone-integrated RPA-CRISPR/Cas12a detection system with microneedle sampling for early point-of-care diagnosis
Jiangnan Zhao1, Hanbo Xu1, Shifang Fei2
1Key Laboratory of Smart Agriculture Systems, Ministry of Education, College of Information and Electrical Engineering, China Agricultural University, Beijing, 100083, China; Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs of China, College of Information and Electrical Engineering, China Agricultural University, Beijing, 100083, China.
Abstract:
Potato late blight, caused by the oomycete pathogen Phytophthora infestans (P. infestans), is one of the most devastating diseases threatening global potato production. Conventional plant disease detection methods rely on a labor-intensive and time-consuming workflow and require bulky and expensive benchtop equipment, limiting their in-field applications. Here, we report a portable RPA-CRISPR/Cas12a-based diagnostic platform integrated with a polyvinyl alcohol (PVA) microneedle (MN) patch, which allows rapid in-field sampling, and smartphone-based fluorescence acquisition and analysis to detect P. infestans in potato at the early stage. The PVA MN enables leaf sampling rapidly within 1 min, and yields efficient DNA extraction of 56.3 ± 4.2 ng/mg, which is ∼3-fold higher than the traditional CTAB method (18.1 ± 2.1 ng/mg). The RPA-CRISPR/Cas12a isothermal assay achieved specific detection of P. infestans with no cross-reactivity against closely-related species Phytophthora sojae or Phytophthora capsici. The smartphone-based point-of-care test (POCT) system demonstrates a detection limit of 4 pg/μL for P. infestans genomic DNA, which is comparable to that acquired with commercial laboratory equipment. The method enables early-stage diagnosis of potato late blight as early as Day 2 post-inoculation, with detection rates of 37.5% on Day 2 and 75% on Day 3, prior to the development of visible symptoms on leaves. This portable "sample-to-result" platform provides a promising strategy for rapid, field-deployable early diagnosis and surveillance of plant disease.
