| 1. |
- Muhlenbock, Per, et al.
(författare)
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Chloroplast Signaling and LESION SIMULATING DISEASE1 Regulate Crosstalk between Light Acclimation and Immunity in Arabidopsis
- 2008
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 20:9, s. 2339-2356
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Tidskriftsartikel (refereegranskat)abstract
- Plants are simultaneously exposed to abiotic and biotic hazards. Here, we show that local and systemic acclimation in Arabidopsis thaliana leaves in response to excess excitation energy (EEE) is associated with cell death and is regulated by specific redox changes of the plastoquinone (PQ) pool. These redox changes cause a rapid decrease of stomatal conductance, global induction of ASCORBATE PEROXIDASE2 and PATHOGEN RESISTANCE1, and increased production of reactive oxygen species (ROS) and ethylene that signals through ETHYLENE INSENSITIVE2 (EIN2). We provide evidence that multiple hormonal/ROS signaling pathways regulate the plant's response to EEE and that EEE stimulates systemic acquired resistance and basal defenses to virulent biotrophic bacteria. In the Arabidopsis LESION SIMULATING DISEASE1 (lsd1) null mutant that is deregulated for EEE acclimation responses, propagation of EEE-induced programmed cell death depends on the plant defense regulators ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4). We find that EDS1 and PAD4 operate upstream of ethylene and ROS production in the EEE response. The data suggest that the balanced activities of LSD1, EDS1, PAD4, and EIN2 regulate signaling of programmed cell death, light acclimation, and holistic defense responses that are initiated, at least in part, by redox changes of the PQ pool.
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| 2. |
- Plaszczyca, Malgorzata, et al.
(författare)
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The role of ASCORBATE PEROXIDASE 2 in systemic signaling in Arabidopsis thaliana
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Plants have to survive in a changing environment and adapt to different abiotic stresses like changes in light intensity or temperature, flooding and soil salinity. Stress conditions cause the increased production of reactive oxygen species (ROS). ROS detoxification requires the activity of different antioxidant systems, among them the H2O2 scavenging enzymes, ascorbate peroxidases (APXs). Many APX forms exist; specifically, a cytosolic APX2 whose expression is restricted to bundle sheath cells and is induced upon accumulation of H2O2 in the chloroplasts of these cells. While the regulation of APX2 expression is well examined, not much is known about its function. Here, the characterization of two APX2 knockout lines from Arabidopsis thaliana is described. The results indicated that APX2 activity does not affect resistance against excess light stress, but systemic signaling in response to excess light treatment.
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