Early Detection of Phytopathogen: An Impedance Spectroscopy-Based DNA Biosensor for Pre-Symptomatic Identification of Ralstonia solanacearum in Solanum melongena

This study presents the first report of an innovative impedimetric DNA-based biosensor designed for the early detection of Ralstonia solanacearum, a notorious pathogen causing bacterial wilt in eggplants within one day of its infection. The novelty of this wok lies in the use of a DNA probe specific to lpxC4 gene of R. solanacearum immobilized on a gold interdigitated electrode, allowing for the detection of the pathogen before the onset of visible symptoms. This unprecedented capability of detecting R. solanacearum at an asymptomatic stage offers a significant breakthrough in plant disease management. In our previous work, we demonstrated the comprehensive development of a label-free, ultra-low sample volume, DNA-based biosensor to detect R. solanacearum utilizing non-faradaic electrochemical impedance spectroscopy (nf-EIS). We also evaluated the sensor's sensitivity, specificity, and electrochemical stability. In this study, we report for the first time on the sensor's sensitivity in detecting DNA hybridization in Solanum melongena (eggplant) in relation to their infection cycle. Early diagnosis of plant pathogens is critical for efficient disease management in agriculture. R. solanacearum normally has an infection cycle of around seven days, with obvious symptoms developing in the later stages. However, the described sensor is capable of detecting R. solanacearum by Day 1 of infection cycle.