Ph. D. Loriane MERLEN

Formulation et phytopharmaceutique : le cas du Subsalicylate de Bismuth, un composé fongistatique et stimulateur des défenses des plantes.

Thesis defended on November, 2022 in Colmar.

Thesis supervisor: Pr. Christelle DELAITE, University of Haute Alsace

Thesis co-supervisor: PhD. Melanie GELLON, Associate Professor, University of Haute Alsace

Abstract:

Since the ban on the use of sodium arsenite in France in 2001, a considerable increase in the number of vines affected by grapevine trunk diseases (GTDs) has been observed. The lack of effective control product led to the development of the Bismuth Subsalicylate (BSS) research project, the topic of this thesis. Bismuth subsalicylate has been used for decades in pharmaceuticals like PeptoBismol®. The dual effect of this compound was studied: both antifungal properties on GTDs-pathogens and an ability to stimulate plant defense genes were investigated, since BSS contains salicylic acid, a secondary metabolite naturally produced by plants.

The aim of the doctoral thesis was to develop appropriate formulations for BSS, naturally insoluble in water. Two formulations were established with sufficiently small particle sizes to increase the bioavailability of the compound. In vitro confirmation of the antifungal properties of the newly formulated BSS on fungi involved in GTDs was performed for the first formulation. The induction of defense genes was analyzed by RT-qPCR and the non-toxicity of BSS was also verified by fluorescence microscopy techniques on Vitis vinifera cv. Gewurztraminer callus for this same formulation. The efficacy of the formulation was then evaluated in planta, in the vineyard, by the vertical plant endotherapy technique, developed at LVBE.

A second formulation to be applied as a pruning wound protection was developed. This latter oneallows for obtaining durable protection, generating less drift of the product. This manuscript proposes two optimized formulations.

Concurrently, another study evaluating the antifungal properties of extracts from industrial waste derived from the forest-wood sector, has been carried out on pathogens involved in GTDs. Preliminary results of this study on the development of phyto-based control agents are also presented in this manuscript.

Keywords: grapevine trunk diseases, bismuth subsalicylate, antifungal, plant defense stimulator, vertical plant endotherapy, wood extracts.