Effects of Verticillium infection on cell biology and development of Arabidopsis thaliana and Brassica napus

Verticillium longisporum is a soil-borne fungal pathogen which causes vascular disease in oilseed rape and other members of the family Brassicaceae. The fungus enters via the plant root system, invades the xylem vessels and then systemically colonizes the hypocotyl and shoot xylem elements. We use GFP and RFP-labeled Verticillium strains to study the infection process in Arabidopsis thaliana. As the fungus proliferates into the leaf vascular bundles, transdifferentiation of mesophyll cells to xylem elements was observed in A. thaliana and Brassica napus. We currently study the role of transcription factors involved in the Verticillium induced transdifferentiation.
At late stages of infection coinciding with leave senescence, the fungus starts to grow out of the vascular tissue and switches from biotrophy to a saprophytic lifestyle. We observed that cytokinin-mediated inhibition of plant senescence compromises proliferation of the fungus. We conclude that cytokinin level modulation may be necessary for fungal lifecycle completion.

RFP-labelled Verticillium strain on Arabidopsis root. The actin cytoskeleton of Arabidopsis is visualized by fimbrin-GFP.