UPSC Seminar with Charles Melnyk

Speaker: Charles Melnyk

Department of Plant Biology, Uppsala, SLU

Title: The hormonal regulation of parasitic plant infection

Abstract:
Parasitic plants are globally prevalent pathogens that attach to and infect a wide range of plant hosts. Key to their success is the formation of the haustorium that fuses to and invades hosts tissues to connect to the vasculature of often distantly related species. Despite their agricultural impact and ecological importance, we have little understanding of how such haustoria form and successfully infect. Here, I will discuss my group’s efforts to understand the developmental basis of plant parasitism and haustoria formation using the parasitic plant Phtheirospermum japonicum and host Arabidopsis thaliana. I will present our work showing that high nitrogen levels act as an external cue to repress haustoria formation via the hormone ABA. I will also present our recent work looking at the systemic regulation of haustoria formation. There, we have uncovered a mechanism whereby existing haustoria repress the formation of future haustoria. This auto-regulation acts systemically in the parasite and depends on the mobile hormone cytokinin that is locally upregulated in haustoria during infection. Altogether, our research sheds light on the importance of cytokinin and ABA to regulate haustoria numbers according to both local and environmental cues to balance resource acquisition.