title: Identification of positive and negative regulators of disease resistance to rice blast fungus using constitutive gene expression patterns.
abstract: Elevated constitutive expression of components of the defence arsenal is associated with quantitative resistance to the rice blast fungus, a phenomenon called preformed defence. While the role of many disease regulators in inducible defence systems has been extensively studied, little attention has been paid so far to genes that regulate preformed defence. In this study, we show by microarray analysis across rice diversity that the preformed defence phenomenon impacts on a large number of defence-related genes without apparently affecting other biological processes. Using a guilt-by-association strategy, we identified two positive regulators that promote constitutive expression of known defence markers and partial resistance to rice blast. The HSF23 gene encodes for a putative member of the heat shock transcription factor family, while CaMBP encodes for a putative Calmodulin-binding protein. Both HSF23 and CaMBP strongly affect preformed defence and also plant growth. Additionally, we identified the OB-fold gene as a negative regulator of blast resistance, which could be involved in RNA stabilization. The OB-fold mutants do not suffer from obvious developmental defects. Taken together, our results prove that our strategy of combining analysis of gene expression diversity with guilt-by-association is a powerful way to identify disease resistance regulators in rice.
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Campus International de Baillarguet, Montpellier, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Grand
authors.forename: Rocio
authors.initials: R
authors.lastname: Espinoza
authors.forename: Corinne
authors.initials: C
authors.lastname: Michel
authors.forename: Sandrine
authors.initials: S
authors.lastname: Cros
authors.forename: Véronique
authors.initials: V
authors.lastname: Chalvon
authors.forename: John
authors.initials: J
authors.lastname: Jacobs
authors.forename: Jean-Benoit
authors.initials: JB
authors.lastname: Morel
mesh_terms: D060467:Disease Resistance / Q000235:genetics* / Q000276:immunology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D056726:Genetic Association Studies; D020082:Magnaporthe / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction