Quick discrimination of live and dead sclerotia of allium white rot pathogen (Sclerotium cepivorum) by fluorescent vital staining with fluorescein diacetate hydrolysis

Abstract

We demonstrated a method for the quick discrimination of live and dead sclerotia of the allium white rot pathogen (Sclerotium cepivorum Berkeley) by vital staining with fluorescein diacetate (FDA) hydrolysis. Surface-sterilized sclerotia were cracked by forceps and placed on a water agar plate. Within 20–30 min after the application of 1.25–10 ppm FDA, bright green fluorescence was observed from within and around the sclerotia under blue light (480 nm ). Water agar (background) and autoclaved (dead) sclerotia emitted negligible fluorescence with 10 ppm FDA. Inhibition of sclerotial germination by cyanamide did not affect fluorescence. FDA application did not suppress germination and growth of sclerotia. This method can be used to assess the viability of sclerotia quickly.