Fourier-transform infrared spectroscopic and microscopic study of the infection of potato tubers by Erwinia carotovora ssp carotovora in aerobic and anaerobic conditions

The infection of potato tubers (Solanum tuberosum) by Erwinia carotovora ssp carotovora in aerobic and anaerobic conditions was studied using chemical analysis and Fourier-transform infrared (FT-IR) microscopy and diffuse reflectance spectroscopy. Analysis of the uninfected and infected residues following sequential extraction with diethyl ether, water (40 degrees C), 90% dimethyl sulphoxide (DMSO) and digestion with amyloglucosidase showed that the principal effect of infection, particularly in anaerobic conditions, is starch degradation. This was substantiated by gel filtration chromatography of the 90% DMSO extracts. Extensive lignification was not found to be intimately associated with either infective condition. FT-IR microscopical analysis of tissue sections showed that infection in both aerobic and anaerobic conditions caused starch and cell wall degradation, whilst extensive membrane degradation was only evident with anaerobic infection.