| 1. |
- Karpinski, Stanislaw, et al.
(författare)
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Genetic, molecular and physiological mechanisms controlling cell death, defenses, and antioxidant network in response to abiotic and biotic stresses in plants
- 2007
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Ingår i: Abstracts of the Annual Main Meeting of the Society for Experimental Biology, Glasgow, Scotland, 31st March - 4th April, 2007. - : Elsevier BV.
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Konferensbidrag (populärvet., debatt m.m.)
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| 2. |
- Meng, Meng, et al.
(författare)
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Differential tissue/organ-dependent expression of two sucrose- and cold-responsive genes for UDP-glucose pyrophosphorylase in Populus.
- 2007
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Ingår i: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 389:2, s. 186-95
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Tidskriftsartikel (refereegranskat)abstract
- Plant UDP-glucose (UDPG) pyrophosphorylase (UGPase) is involved in the production/metabolism of UDPG, a key metabolite for sucrose and cell wall biosynthesis. Two highly similar cDNAs (UGP1 and UGP2) corresponding to UGPase were isolated from cDNA libraries of hybrid aspen (Populus tremula x tremuloides). Expression of both UGPs, as studied by DNA microarrays and EST abundance, was compared to that of three sucrose synthase genes (SUS1–3), also involved in UDPG synthesis. Generally, the UGPs had lower expression than SUS1 and SUS2 genes (especially in tension wood and cambium), with the notable exception of leaves, primary roots and flowers. Based on real-time quantitative PCR, UGP1 in root xylem, leaves and male flowers was by far the predominant transcript, while in other tissues both UGP1 and UGP2 had comparable expression. In leaves, the UGP1 gene, but not UGP2, was upregulated by light and short-term sucrose feeding. Cold treatment led to dramatic organ-specific changes in relative expression of both genes, with UGP2 being upregulated either transiently (leaves), long-term (stems) or not at all (roots), whereas UGP1 was cold-upregulated in all organs. Individual or overall UGP expression patterns only weakly correlated with UGPase activity/protein; however, UGPase activity and protein were correlated in all tissues/conditions. The data suggest that UGPs are differentially expressed at the tissue level and in response to metabolic feedback (sucrose) and cold stress, and point to a tight posttranscriptional/translational control and, possibly, distinct roles for those genes.
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| 3. |
- 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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| 4. |
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| 5. |
- Slesak, Ireneusz, et al.
(författare)
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The role of hydrogen peroxide in regulation of plant metabolism and cellular signalling in response to environmental stresses
- 2007
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Ingår i: Acta Biochimica Polonica. - 0001-527X .- 1734-154X. ; 54:1, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen peroxide (H2O2) is produced predominantly in plant cells during photosynthesis and photorespiration, and to a lesser extent, in respiration processes. It is the most stable of the so-called reactive oxygen species (ROS), and therefore plays a crucial role as a signalling molecule in various physiological processes. Intra- and intercellular levels of H2O2 increase during environmental stresses. Hydrogen peroxide interacts with thiol-containing proteins and activates different signalling pathways as well as transcription factors, which in turn regulate gene expression and cell-cycle processes. Genetic systems controlling cellular redox homeostasis and H2O2 signalling are discussed. In addition to photosynthetic and respiratory metabolism, the extracellular matrix (ECM) plays an important role in the generation of H2O2, which regulates plant growth, development, acclimatory and defence responses. During various environmental stresses the highest levels of H2O2 are observed in the leaf veins. Most of our knowledge about H2O2 in plants has been obtained from obligate C-3 plants. The potential role of H2O2 in the photosynthetic mode of carbon assimilation, such as C-4 metabolism and CAM (Crassulacean acid metabolism) is discussed. We speculate that early in the evolution of oxygenic photosynthesis on Earth, H2O2 could have been involved in the evolution of modem photosystem II.
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