Potential of Spatially Offset Raman Spectroscopy for Detection of Zebra Chip and Potato Virus Y Diseases of Potatoes (<i>Solanum tuberosum</i>)
Charles M. Farber, Lee Sanchez, Shankar R. Pant, Douglas C. Scheuring, M. Isabel Vales, Kranthi K. Mandadi, Dmitry Kurouski
Abstract
Potato (Solanum tuberosum L.) is a staple food crop and part of an industry valued at an estimated $3.77 billion in the United States. Many varieties of potato are susceptible to zebra chip disease (ZC), a psyllid-vectored bacterial infection that renders the tubers unmarketable due to unappealing discoloration and taste. Similarly, potato virus Y (PVY) is a major pathogen of potatoes and other solanaceous crops that causes devastating damage to both foliage and tubers. These diseases are typically detected by enzyme-linked immunosorbent assay or polymerase chain reaction. ZC can also be diagnosed by a visual inspection of cut open tubers followed by frying to reveal the characteristic striping symptoms. However, these methods are invasive and destructive, as well as reagent, time, and labor consuming. Thus, quick and sample-general alternative methods for disease detection are highly desirable. In this proof-of-principle work, we demonstrate that spatially offset Raman spectroscopy (SORS) shows great potential for rapid and reagent-free detection of ZC or PVY diseases. Such detection is based on Raman identification of chemical changes in tubers associated with ZC or PVY. Chemometric analysis of spectra from intact potato tubers demonstrated over 90% accuracy of ZC detection. With data from cut open tubers, the prediction accuracy for ZC increased to over 90% for the prediction of PVY disease. We also show that potatoes from plants with either ZC or PVY diseases can be distinguished from each other and healthy tubers with approximately 95% accuracy. These results suggest that SORS has potential for noninvasive diagnostics of potato diseases.