Rapid and non-destructive detection of Pectobacterium carotovorum causing soft rot in stored potatoes through volatile biomarkers sensing

Early disease detection plays a significant role in the pre- and post-production management of specialty crops, that often are stored for several months prior to consumption. Potato is one of the most important specialty crops of the United States. However, soft rot in potatoes due to pathogenic infections during bulk storage, accounts for substantial losses to the industry. This study was aimed at assessing the applicability of an emerging technology, portable field asymmetric ion mobility spectrometry (FAIMS), towards early detection of soft rot in potatoes during bulk storage. The FAIMS senses mobility of ions pertinent to volatile organic compounds (VOCs) released from inoculated tubers. In this study, potato tubers, inoculated with Pectobacterium carotovorum causing soft rot, were analyzed using FAIMS over a 30-day period in storage. Sterile water inoculated tubers were considered as healthy controls. Results suggest that FAIMS can detect soft rot as early as two days after inoculation (DAI) by effectively capturing VOCs associated with rot progression. The activity of pathogen and associated VOCs release was maximum during the second week after inoculation. A principal component analysis showed a clear distinction between the healthy and P. carotovorum inoculated tubers. Classification models, quadratic discriminant analysis and Naïve Bayes with leave-one-out cross validation confirmed the validity of FAIMS response with accuracies between 83 and 100% for both healthy and P. carotovorum inoculated tubers.