Emerging and re-emerging plant diseases such as late blight disease caused by <i>Phytophthora infestans</i> is one of the most severe agricultural diseases, which accounts for an annual financial loss of nearly five billion dollars. Plant disease diagnosis conventionally relies on molecular technology that is complicated, time consuming, and constrained to centralized laboratories. Herein we developed a cost-effective smartphone-based volatile organic compound (VOC) fingerprinting platform that allows for noninvasive diagnosis of late blight by monitoring characteristic leaf volatile emissions in the headspace. This handheld device integrates a disposable colorimetric sensor array consisted of plasmonic nanocolorants and chemo-responsive organic dyes to detect key plant volatiles at ppm level detection limit within one minute of gas exposure. We demonstrate the multiplexed detection and classification of 10 individual plant volatiles with this field-portable VOC sensing platform, which permits early determination of tomato late blight only 2 days after inoculation, and differentiation from other fungal infections that lead to similar symptoms of tomato foliage. Furthermore, we demonstrate 95% detection accuracy in diagnosis of <i>P. infestans</i> among lab-inoculated or field-collected tomato leaves in a blind pilot test. Considering the flexibility of sensor array design, multiplexability, and cost-effectiveness, this integrated optical sensor platform can be promisingly applied to detect a variety of common pathogenic infections at very early stages, as well as monitor numerous abiotic stresses of plants in the field.

Noninvasive diagnosis of tomato late blight via smartphone fingerprinting of leaf volatiles

2019 Spring National Meeting

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