title: Double antisense plants lacking ascorbate peroxidase and catalase are less sensitive to oxidative stress than single antisense plants lacking ascorbate peroxidase or catalase.
abstract: The plant genome is a highly redundant and dynamic genome. Here, we show that double antisense plants lacking the two major hydrogen peroxide-detoxifying enzymes, ascorbate peroxidase (APX) and catalase (CAT), activate an alternative/redundant defense mechanism that compensates for the lack of APX and CAT. A similar mechanism was not activated in single antisense plants that lacked APX or CAT, paradoxically rendering these plants more sensitive to oxidative stress compared to double antisense plants. The reduced susceptibility of double antisense plants to oxidative stress correlated with suppressed photosynthetic activity, the induction of metabolic genes belonging to the pentose phosphate pathway, the induction of monodehydroascorbate reductase, and the induction of IMMUTANS, a chloroplastic homologue of mitochondrial alternative oxidase. Our results suggest that a co-ordinated induction of metabolic and defense genes, coupled with the suppression of photosynthetic activity, can compensate for the lack of APX and CAT. In addition, our findings demonstrate that the plant genome has a high degree of plasticity and will respond differently to different stressful conditions, namely, lack of APX, lack of CAT, or lack of both APX and CAT.
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel.
authors.forename: Ludmila
authors.initials: L
authors.lastname: Rizhsky
authors.forename: Elza
authors.initials: E
authors.lastname: Hallak-Herr
authors.forename: Frank
authors.initials: F
authors.lastname: Van Breusegem
authors.forename: Shimon
authors.initials: S
authors.lastname: Rachmilevitch
authors.forename: Jason E
authors.initials: JE
authors.lastname: Barr
authors.forename: Steven
authors.initials: S
authors.lastname: Rodermel
authors.forename: Dirk
authors.initials: D
authors.lastname: Inzé
authors.forename: Ron
authors.initials: R
authors.lastname: Mittler
mesh_terms: D016375:Antisense Elements (Genetics) / Q000235:genetics; D060387:Ascorbate Peroxidases; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology; D020869:Gene Expression Profiling / Q000379:methods; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology; D011549:Pseudomonas / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology
chemical_list: D016375:Antisense Elements (Genetics); D017382:Reactive Oxygen Species; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase