Characterization of volatile signatures of Pectobacterium and Dickeya spp. as biomarkers for early detection and identification - A major tool in potato blackleg and tuber soft rot management

Potato blackleg and tuber soft rot diseases, caused by the pectinolytic bacteria Pectobacterium and Dickeya spp., result in severe yield losses worldwide. Early detection of pectinolytic bacterial infections is an important tool in disease management for sustainable potato production. The main goal of the current study was to profile the volatile composition of tubers inoculated with pectinolytic bacteria, in order to identify biomarkers for inoculation with different pathogens. Potato tubers were inoculated with two genera of bacteria (five species and/or sub-species, 4-5 strains of each). The headspace was sampled via solid-phase microextraction method, and volatiles were further profiled using gas chromatography-mass spectrometry. Using discriminant analysis, we were able to identify volatiles as differentiating biomarkers, indicating either non-specific or species-specific inoculation. Dimethyl ether was increased in all inoculated samples regardless of the genus or species; hexanal was increased in inoculation with Dickeya compared to Pectobacterium; 2-methylbutanol and 2,3-octanedione differentiated between Pectobacterium species inoculation; and 2-pentyl thiophene differentiated between Dickeya species inoculation. Early detection of pectinolytic bacteria through continuous monitoring of storage facility and tuber shipments atmosphere may be a powerful tool in preventing and mitigating tuber soft rots, avoiding severe economic damages and global food loss.