title: Concurrent overactivation of the cytosolic glutamine synthetase and the GABA shunt in the ABA-deficient sitiens mutant of tomato leads to resistance against Botrytis cinerea.
abstract: Deficiency of abscisic acid (ABA) in the sitiens mutant of tomato (Solanum lycopersicum) culminates in increased resistance to Botrytis cinerea through a rapid epidermal hypersensitive response (HR) and associated phenylpropanoid pathway-derived cell wall fortifications. This study focused on understanding the role of primary carbon : nitrogen (C : N) metabolism in the resistance response of sitiens to B. cinerea. How alterations in C : N metabolism are linked with the HR-mediated epidermal arrest of the pathogen has been also investigated. Temporal alterations in the γ-aminobutyric acid (GABA) shunt, glutamine synthetase/glutamate synthase (GS/GOGAT) cycle and phenylpropanoid pathway were transcriptionally, enzymatically and metabolically monitored in both wild-type and sitiens plants. Virus-induced gene silencing, microscopic analyses and pharmacological assays were used to further confirm the data. Our results on the sitiens-B. cinerea interaction favor a model in which cell viability in the cells surrounding the invaded tissue is maintained by a constant replenishment of the tricarboxylic acid (TCA) cycle through overactivation of the GS/GOGAT cycle and the GABA shunt, resulting in resistance through both tightly controlling the defense-associated HR and slowing down the pathogen-induced senescence. Collectively, this study shows that maintaining cell viability via alterations in host C : N metabolism plays a vital role in the resistance response against necrotrophic pathogens.
authors.affiliation: Laboratory of Phytopathology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Hamed Soren
authors.initials: HS
authors.lastname: Seifi
authors.affiliation: Laboratory of Applied Molecular Genetics, Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Katrien
authors.initials: K
authors.lastname: Curvers
authors.affiliation: Laboratory of Phytopathology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: De Vleesschauwer
authors.affiliation: Laboratory of Phytopathology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Ilse
authors.initials: I
authors.lastname: Delaere
authors.affiliation: Laboratory of SDRP - URVVC EA 4707, University of Reims, Campus Moulin de la Housse, 51687, Reims Cedex 2, France.
authors.forename: Aziz
authors.initials: A
authors.lastname: Aziz
authors.affiliation: Laboratory of Phytopathology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Monica
authors.initials: M
authors.lastname: Höfte
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D020171:Botrytis / Q000502:physiology*; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D060467:Disease Resistance / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D054884:Host-Pathogen Interactions / Q000187:drug effects; D018551:Solanum lycopersicum / Q000166:cytology / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D020005:Propanols / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D020005:Propanols; D012333:RNA, Messenger; C439395:1-phenylpropanol; D005680:gamma-Aminobutyric Acid; D000040:Abscisic Acid; D010650:Phenylalanine Ammonia-Lyase; D005974:Glutamate-Ammonia Ligase