Powdery mildew of Arabidopsis thaliana: a pathosystem for exploring the role of silicon in plant–microbe interactions

• Published in: Physiological and molecular plant pathology Vol. 64; no. 4; pp. 189 - 199
• Main Authors: Ghanmi, Dalila, McNally, David J., Benhamou, Nicole, Menzies, Jim G., Bélanger, Richard R.
• Format: Journal Article
• Language: English
• Published: London Elsevier India Pvt Ltd 01.04.2004; Elsevier
• Subjects: Arabidopsis thaliana; Biological and medical sciences; Defense reactions; Erysiphe cichoracearum; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; host-pathogen relationships; Induced resistance; Phytopathology. Animal pests. Plant and forest protection; plant morphology; plant pathogenic fungi; Plant–pathogen interactions; Powdery mildew; Silicon; ultrastructure; X-ray microanalysis mapping; Arabidopsis thaliana; Defense reactions; Plant–pathogen interactions; X-ray microanalysis mapping; Erysiphe cichoracearum; Silicon; Induced resistance; Powdery mildew; Non metal; Plant pathology; Plant pathogen; Mycosis; Host agent relation; Group IVA element; Biological system; Fungi; Infection; Cruciferae; Dicotyledones; Angiospermae; Ascomycetes; Spermatophyta; Experimental plant; Thallophyta; Plant microorganism relation
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1016/j.pmpp.2004.07.005

Silicon (Si) has been used in agriculture to protect plants against disease for hundreds of years and its prophylactic effects in monocots and dicots are well documented. The mechanisms by which Si exerts its protective effects in planta, however, are uncertain and presently the subject of debate. In this study, we sought to determine if Arabidopsis thaliana could be used to clarify the role of Si in plant–pathogen interactions. Accordingly, X-ray microanalysis mapping, light microscopy, scanning and transmission electron microscope techniques were used to examine the leaves of Si− fed A. thaliana plants inoculated with the powdery mildew fungus, Erysiphe cichoracearum. The results of this study demonstrate for the first time, that A. thaliana is a species that absorbs Si and that the incidence of powdery mildew disease for Si− fed plants is significantly lower compared to control plants. In particular, treatment with Si appeared to induce the production of an electron-dense, fungitoxic substance that accumulated within and around the collapsed fungal haustoria of infected epidermal cells within the leaves of disease-resistant plants. These results with Arabidopsis corroborate recent observations in other non-related species and support the emerging theory that the mechanisms by which Si imparts resistance to plants are complex and are not entirely explained by the traditionally proposed role of Si as a reinforcer of mechanical resistance. Collectively, the findings of the present study have established the Arabidopsis thaliana- Erysiphe cichoracearum pathosystem as a valid model to investigate the role of Si in plant–microbe interactions.