Biosensors Used for Epifluorescence and Confocal Laser Scanning Microscopies to Study <i>Dickeya</i> and <i>Pectobacterium</i> Virulence and Biocontrol

• Main Authors: Yvann Bourigault, Andrea Chane, Corinne Barbey, Sylwia Jafra, Robert Czajkowski, Xavier Latour
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Microorganisms
• Subjects: fluorescent proteins; green fluorescent protein (GFP); microscopy; plant colonization; <i>Dickeya</i>; <i>Pectobacterium</i>
• Online Access: https://www.mdpi.com/2076-2607/9/2/295

Promoter-probe vectors carrying fluorescent protein-reporter genes are powerful tools used to study microbial ecology, epidemiology, and etiology. In addition, they provide direct visual evidence of molecular interactions related to cell physiology and metabolism. Knowledge and advances carried out thanks to the construction of soft-rot <em>Pectobacteriaceae</em> biosensors, often inoculated in potato <em>Solanum tuberosum</em>, are discussed in this review. Under epifluorescence and confocal laser scanning microscopies, <em>Dickeya</em> and <em>Pectobacterium</em>-tagged strains managed to monitor in situ bacterial viability, microcolony and biofilm formation, and colonization of infected plant organs, as well as disease symptoms, such as cell-wall lysis and their suppression by biocontrol antagonists. The use of dual-colored reporters encoding the first fluorophore expressed from a constitutive promoter as a cell tag, while a second was used as a regulator-based reporter system, was also used to simultaneously visualize bacterial spread and activity. This revealed the chronology of events leading to tuber maceration and quorum-sensing communication, in addition to the disruption of the latter by biocontrol agents. The promising potential of these fluorescent biosensors should make it possible to apprehend other activities, such as subcellular localization of key proteins involved in bacterial virulence <em>in planta</em>, in the near future.