| 1. |
- Mühlenbock, Per, et al.
(författare)
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Lysigenous Aerenchyma Formation in Arabidopsis is Controlled by LESION SIMULATING DISEASE1
- 2007
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 19:11, s. 3819-3830
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Tidskriftsartikel (refereegranskat)abstract
- Aerenchyma tissues form gas-conducting tubes that provide rootswith oxygen under hypoxic conditions. Although aerenchyma havereceived considerable attention in Zea mays, the signaling eventsand genes controlling aerenchyma induction remain elusive. Here,we show that Arabidopsis thaliana hypocotyls form lysigenousaerenchyma in response to hypoxia and that this process involvesH2O2 and ethylene signaling. By studying Arabidopsis mutantsthat are deregulated for excess light acclimation, cell death,and defense responses, we find that the formation of lysigenousaerenchyma depends on the plant defense regulators LESION SIMULATINGDISEASE1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), andPHYTOALEXIN DEFICIENT4 (PAD4) that operate upstream of ethyleneand reactive oxygen species production. The obtained resultsindicate that programmed cell death of lysigenous aerenchymain hypocotyls occurs in a similar but independent manner fromthe foliar programmed cell death. Thus, the induction of aerenchymais subject to a genetic and tissue-specific program. The datalead us to conclude that the balanced activities of LSD1, EDS1,and PAD4 regulate lysigenous aerenchyma formation in responseto hypoxia.
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| 2. |
- Plaszczyca, Malgorzata, et al.
(författare)
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Salt stress responses in nodules of two actinorhizal plant species, Datisca glomerata and Casuarina glauca
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Soil salinization is a factor in declining crop yields worldwide. Salt tolerance depends on the plant antioxidant defense system. Nitrogen availability is essential to agriculture and land reclamation. Some nitrogen-fixing bacteria can enter symbioses with higher plants - rhizobia with legumes, and Frankia strains with actinorhizal plants. In both symbioses, the plants form special organs, root nodules, wherein they host the bacterial endosymbionts. Rhizobial nitrogen fixation in legume nodules in combination with the oxygen protection system, leads to the production of reactive oxygen species (ROS) which require a high activity of antioxidant defense, a fact which has been thought to be responsible for the salt sensitivity of legumes. Actinorhizal oxygen protection systems for bacterial nitrogen fixation in nodules are more diverse, and actinorhizal plants tend to show salt tolerance. In this study, the antioxidant defense systems were examined in two actinorhizal species, Casuarina glauca which has an oxygen protection system similar to those of legumes, and Datisca glomerata which has a different system. The results indicated that the subcellular location of hydrogen peroxide production differed in infected cells of both plants, namely, the cytosol in C. glauca and the symbiotic bacteria in D. glomerata. Studies of enzymes and metabolites involved in antioxidant defense indicated that the glutathione-ascorbate cycle is far more active in D. glomerata than in C. glauca nodules, while the latter have higher catalase activities.
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| 3. |
- Demina, Irina V., et al.
(författare)
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Comparison of the Nodule vs. Root Transcriptome of the Actinorhizal Plant Datisca glomerata : Actinorhizal Nodules Contain a Specific Class of Defensins
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8, s. e72442-
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Tidskriftsartikel (refereegranskat)abstract
- Actinorhizal root nodule symbioses are very diverse, and the symbiosis of Datisca glomerata has previously been shown to have many unusual aspects. In order to gain molecular information on the infection mechanism, nodule development and nodule metabolism, we compared the transcriptomes of D. glomerata roots and nodules. Root and nodule libraries representing the 3'-ends of cDNAs were subjected to high-throughput parallel 454 sequencing. To identify the corresponding genes and to improve the assembly, Illumina sequencing of the nodule transcriptome was performed as well. The evaluation revealed 406 differentially regulated genes, 295 of which (72.7%) could be assigned a function based on homology. Analysis of the nodule transcriptome showed that genes encoding components of the common symbiosis signaling pathway were present in nodules of D. glomerata, which in combination with the previously established function of SymRK in D. glomerata nodulation suggests that this pathway is also active in actinorhizal Cucurbitales. Furthermore, comparison of the D. glomerata nodule transcriptome with nodule transcriptomes from actinorhizal Fagales revealed a new subgroup of nodule-specific defensins that might play a role specific to actinorhizal symbioses. The D. glomerata members of this defensin subgroup contain an acidic C-terminal domain that was never found in plant defensins before.
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| 4. |
- 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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