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Marie-Emma Denarié

Candidature

PhD Candidate

Thesis title

The role of silicon in plant-mediated interactions between pests and pathogens

Research project

Marie-Emma DenarieSilicon (Si) is known to have beneficial effects on plants against various biotic stresses such as insect herbivores, fungal pathogens, and plant parasitic nematodes. These antagonists induce different plant defence mechanisms through defensive phytohormone signalling, for instance the salicylic acid (SA) or jasmonic acid (JA) pathway. Si uptake aids defence against chewing herbivores when the JA pathway is triggered mechanically, chemically or with authentic herbivory. However, it is unclear whether the SA pathway, more typical of pathogen and sucking herbivore attack, plays a similar role. Information about how plant Si mediates antagonist interactions is limited to a small number of studies addressing plant-mediated interactions among insect herbivores. It is unknown how Si affects interactions between highly disparate plant antagonists. Therefore, the overarching objective of my research is Si in the context of phytohormonal defence pathways. The key question is whether Si alters host susceptibility to different antagonists and whether plant hormones have the capacity to interfere with each other in Si-induced defence. However, before addressing complex infestations by multiple attackers I will focus on separate plant antagonists to establish Si-related plant response and mechanisms. In this project the aim is to unravel how Si influences the response of wheat (Triticum aestivum) to spot blotch disease (Bipolaris sorokiniana), cotton bollworm (Helicoverpa armigera) and the root lesion nematode (Pratylenchus thornei). The aim is to elucidate the mode-of-action of Si against B. sorokiniana in roots and shoots of wheat. Furthermore, the threshold of impact of Si on susceptibility to H. armigera and B. sorokiniana will be studied. As it is unknown whether Si elicits plant defence responses against P. thornei, this will be investigated. Finally, pairwise inoculations will be performed to assess the role of Si in mediating tripartite interactions.

Publications

Denarie ME, Nielsen UN, Hartley SE, Johnson SN, (2025) 'Silicon-Mediated Interactions Between Plant Antagonists', Plants-Basel, vol.14, no.8, art n.1204

Supervisory panel

Professor Scott Johnson, Professor Uffe Nielsen, Professor Susan Hartley