title: Primary metabolism plays a central role in moulding silicon-inducible brown spot resistance in rice.
abstract: Over recent decades, a multitude of studies have shown the ability of silicon (Si) to protect various plants against a range of microbial pathogens exhibiting different lifestyles and infection strategies. Despite this relative wealth of knowledge, an understanding of the action mechanism of Si is still in its infancy, which hinders its widespread application for agricultural purposes. In an attempt to further elucidate the molecular underpinnings of Si-induced disease resistance, we studied the transcriptome of control and Si-treated rice plants infected with the necrotrophic brown spot fungus Cochliobolus miyabeanus. Analysis of brown spot-infected control plants suggested that C. miyabeanus represses plant photosynthetic processes and nitrate reduction in order to trigger premature senescence and cause disease. In Si-treated plants, however, these pathogen-induced metabolic alterations are strongly impaired, suggesting that Si alleviates stress imposed by the pathogen. Interestingly, Si also significantly increased photorespiration rates in brown spot-infected plants. Although photorespiration is often considered as a wasteful process, recent studies have indicated that this metabolic bypass also enhances resistance during abiotic stress and pathogen attack by protecting the plant's photosynthetic machinery. In view of these findings, our results favour a scenario in which Si enhances brown spot resistance by counteracting C. miyabeanus-induced senescence and cell death via increased photorespiration. Moreover, our results shed light onto the mechanistic basis of Si-induced disease control and support the view that, in addition to activating plant immune responses, Si can also reduce disease severity by interfering with pathogen virulence strategies.
authors.affiliation: Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, B-9000, Ghent, Belgium.
authors.forename: Jonas
authors.initials: J
authors.lastname: Van Bockhaven
authors.affiliation: Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, B-9000, Ghent, Belgium.
authors.forename: Kathy
authors.initials: K
authors.lastname: Steppe
authors.affiliation: Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, B-9000, Ghent, Belgium.
authors.forename: Ingvar
authors.initials: I
authors.lastname: Bauweraerts
authors.affiliation: Plant Genome Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, 305-8602, Ibaraki, Japan.
authors.forename: Shoshi
authors.initials: S
authors.lastname: Kikuchi
authors.affiliation: Plant Genome Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, 305-8602, Ibaraki, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Asano
authors.affiliation: Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, B-9000, Ghent, Belgium.
authors.forename: Monica
authors.initials: M
authors.lastname: Höfte
authors.affiliation: Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, B-9000, Ghent, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: De Vleesschauwer
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity*; D012275:Oryza / Q000382:microbiology*
keywords: Bipolaris oryzae; photorespiration; photosynthesis; plant immunity; plant-microbe interactions; rice; silicon