Nondestructive presymptomatic detection of blue-fluorescing substances in tomato leaves infected with Ralstonia solanacearum using a polyvinyl alcohol hydrogel.

This study proposes a nondestructive technique for the presymptomatic detection of pathogenic infections of plants, aiming to effectively prevent and control plant diseases in agriculture. The present and previous studies indicated that an increase in blue-fluorescing substances, including chlorogenic acid, in tomato leaves is a promising biomarker of infection with the pathogenic soil bacterium Ralstonia solanacearum. A soft and adhesive polyvinyl alcohol (PVA) hydrogel conformably adhered to the hydrophobic surface of the tomato leaf with a complex topography, mediated by non-volatile glycerol, enabling effective extraction of blue-fluorescing substances in a nondestructive manner. The fluorescence intensity of the PVA hydrogel increased a few days before the appearance of visible symptoms of bacterial wilt. This technique is expected to become a fundamental technology for the early detection of plant diseases.