Characterization of Phytophthora infestans resistance to mefenoxam using FTIR spectroscopy
•Infrared spectroscopy may classify resistant P. infestan isolates to mefenoxam fungicide.•A classification success rate of ∼90% was achieved using PCA and LDA.•The averaged spectra gave better classification rates than the individual spectra.
Phytophthora infestans (P. infestans) is the causal agent of late blight in potato and tomato. This pathogen devastated the potato crops in Ireland more than a century years ago and is still causing great losses worldwide. Although fungicides controlling P. infestans have been used successfully for almost 100 years, some isolates have developed resistance to most common fungicides. Identification and characterization of these resistant isolates is required for better control of the disease. Current methods that are based on microbiological and molecular techniques are both expensive and time consuming.Fourier Transform Infra-Red spectroscopy (FTIR) is an inexpensive and reagent-free technique that provides accurate results in only a few minutes. In this study the infrared absorption spectra of the sporangia of P. infestans were measured to evaluate the potential of FTIR spectroscopy in tandem with multivariate analysis in order to classify those sporangia into those that were resistant and those that were non-resistant to the phenylamide fungicide mefenoxam. Based on individual measurements, our results show that FTIR spectroscopy enables classification of P. infestans isolates into mefenoxam resistant and mefenoxam non-resistant types with specificity of 81.9% and sensitivity of 75.5%. Using average spectra per leaf, it was possible to improve the classification results to 88% sensitivity and 95% specificity.
Graphical abstractMajor steps in this study: FTIR spectroscopy may provide a specific, rapid, and inexpensive method for successful differentiation between resistant and non-resistant isolates P. infestans to mefenoxam fungicide.Figure optionsDownload full-size imageDownload as PowerPoint slide
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 141, December 2014, Pages 308–314