title: Impact of biotic and abiotic factors on the expression of fungal effector-encoding genes in axenic growth conditions.
abstract: In phytopathogenic fungi, the expression of hundreds of small secreted protein (SSP)-encoding genes is induced upon primary infection of plants while no or a low level of expression is observed during vegetative growth. In some species such as Leptosphaeria maculans, this coordinated in-planta upregulation of SSP-encoding genes expression relies on an epigenetic control but the signals triggering gene expression in-planta are unknown. In the present study, biotic and abiotic factors that may relieve suppression of SSP-encoding gene expression during axenic growth of L. maculans were investigated. Some abiotic factors (temperature, pH) could have a limited effect on SSP gene expression. In contrast, two types of cellular stresses induced by antibiotics (cycloheximide, phleomycin) activated strongly the transcription of SSP genes. A transcriptomic analysis to cycloheximide exposure revealed that biological processes such as ribosome biosynthesis and rRNA processing were induced whereas important metabolic pathways such as glycogen and nitrogen metabolism, glycolysis and tricarboxylic acid cycle activity were down-regulated. A quantitatively different expression of SSP-encoding genes compared to plant infection was also detected. Interestingly, the same physico-chemical parameters as those identified here for L. maculans effectors were identified to regulate positively or negatively the expression of bacterial effectors. This suggests that apoplastic phytopathogens may react to similar physiological parameters for regulation of their effector genes.
authors.affiliation: UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France. Electronic address: michel.meyer@inra.fr.
authors.forename: Michel
authors.initials: M
authors.lastname: Meyer
authors.affiliation: Université Paris-Sud, 91400 Orsay, France; Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
authors.forename: Salim
authors.initials: S
authors.lastname: Bourras
authors.affiliation: UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Gervais
authors.affiliation: Centre National de Séquençage, CEA-Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry Cedex, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Labadie
authors.affiliation: Centre National de Séquençage, CEA-Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry Cedex, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Cruaud
authors.affiliation: UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Balesdent
authors.affiliation: UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Rouxel
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000254:growth & development; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D005656:Fungal Proteins
keywords: Biotic and abiotic factors; Effector expression; Filamentous pathogenic fungus; Leptosphaeria maculans; Vegetative growth