| 1. |
- Aliakbari, Massume, et al.
(författare)
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Rubisco activase A (RcaA) is a central node in overlapping gene network of drought and salinity in Barley (Hordeum vulgare L.) and may contribute to combined stress tolerance
- 2021
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier. - 0981-9428 .- 1873-2690. ; 161, s. 248-258
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Tidskriftsartikel (refereegranskat)abstract
- Co-occurrence of abiotic stresses, especially drought and salinity, is a natural phenomenon in field conditions and is worse for crop production than any single stress. Nowadays, rigorous methods of meta-analysis and systems biology have made it possible to perform cross-study comparisons of single stress experiments, which can uncover main overlapping mechanisms underlying tolerance to combined stress. In this study, a meta-analysis of RNA-Seq data was conducted to obtain the overlapping gene network of drought and salinity stresses in barley (Hordeum vulgare L.), which identified Rubisco activase A (RcaA) as a hub gene in the dual-stress response. Thereafter, a greenhouse experiment was carried out using two barley genotypes with different abiotic stress tolerance and evaluated several physiochemical properties as well as the expression profile and protein activity of RcaA. Finally, machine learning analysis was applied to uncover relationships among combined stress tolerance and evaluated properties. We identified 441 genes which were differentially expressed under both drought and salinity stress. Results revealed that the photosynthesis pathway and, in particular, the RcaA gene are major components of the dual-stress responsive transcriptome. Comparative physiochemical and molecular evaluations further confirmed that enhanced photosynthesis capability, mainly through regulation of RcaA expression and activity as well as accumulation of proline content, have a significant association with combined drought and salinity stress tolerance in barley. Overall, our results clarify the importance of RcaA in combined stress tolerance and may provide new insights for future investigations.
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| 2. |
- Andersson, Inger, et al.
(författare)
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Structure and function of Rubisco
- 2008
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 46:3, s. 275-291
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Tidskriftsartikel (refereegranskat)abstract
- Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the major enzyme assimilating CO2 into the biosphere. At the same time Rubisco is an extremely inefficient catalyst and its carboxylase activity is compromised by an opposing oxygenase activity involving atmospheric O2. The shortcomings of Rubisco have implications for crop yield, nitrogen and water usage, and for the global carbon cycle. Numerous high-resolution crystal structures of different forms of Rubisco are now available, including structures of mutant enzymes. This review uses the information provided in these structures in a structure-based sequence alignment and discusses Rubisco function in the context of structural variations at all levels – amino acid sequence, fold, tertiary and quaternary structure – with an evolutionary perspective and an emphasis on the structural features of the enzyme that may determine its function as a carboxylase.
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| 3. |
- Askerlund, Per, et al.
(författare)
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Detection of distinct phosphorylated intermediates of Ca2+-ATPase and H+-ATPase in plasma membranes from Brassica oleracea
- 1993
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Ingår i: Plant physiology and biochemistry (Paris). - 0981-9428 .- 1873-2690. ; 31:5, s. 787-791
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Tidskriftsartikel (refereegranskat)abstract
- Two distinct phosphorylated intermediates representing the Ca2+-ATPase and H+-ATPase, respectively, were detected after phosphorylation of plasma membranes from cauliflower (Brassica oleracea L.) inflorescences with [gammaP-32]ATP and separation of polypeptides in an acidic gel. A 116 kDa polypeptide was identified as a Ca2+-ATPase by its Ca2+-dependent phosphorylation which was enhanced by La3+. A second polypeptide (105 kDa) also phosphorylated in the absence of Ca2+ and was identified as the H+-ATPase by immune blotting.
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| 4. |
- Batista-Santos, Paula, et al.
(författare)
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Is salt stress tolerance in Casuarina glauca Sieb. ex Spreng. associated with its nitrogen-fixing root-nodule symbiosis? An analysis at the photosynthetic level
- 2015
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 96, s. 97-109
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Tidskriftsartikel (refereegranskat)abstract
- Casuarina glauca is an actinorhizal tree which establishes root-nodule symbiosis with N-2-fixing Frankia bacteria. This plant is commonly found in saline zones and is widely used to remediate marginal soils and prevent desertification. The nature of its ability to survive in extreme environments and the extent of Frankia contribution to stress tolerance remain unknown. Thus, we evaluated the ability of C. glauca to cope with salt stress and the influence of the symbiosis on this trait. To this end, we analysed the impact of salt on plant growth, mineral contents, water relations, photosynthetic-related parameters and nonstructural sugars in nodulated vs. non-nodulated plants. Although the effects on photosynthesis and stomatal conductance started to become measurable in the presence of 200 mM NaCl, photochemical (e.g., photosynthetic electron flow) and biochemical (e.g., activity of photosynthetic enzymes) parameters were only strongly impaired when NaCl levels reached 600 mM. These results indicate the maintenance of high tissue hydration under salt stress, probably associated with enhanced osmotic potential. Furthermore, the maintenance of photosynthetic assimilation potential (A(max)), together with the increase in the quantum yield of down-regulated energy dissipation of PSII (Y-NPQ), suggested a down-regulation of photosynthesis instead of photo-damaging effects. A comparison of the impact of increasing NaCl levels on the activities of photosynthetic (RubisCO and ribulose-5 phosphate kinase) and respiratory (pyruvate kinase and NADH-dependent malate dehydrogenase) enzymes vs. photosynthetic electron flow and fluorescence parameters, revealed that biochemical impairments are more limiting than photochemical damage. Altogether, these results indicate that, under controlled conditions, C glauca tolerates high NaCl levels and that this capacity is linked to photosynthetic adjustments.
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| 5. |
- Berglund, Torkel, et al.
(författare)
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Nicotinamide; antioxidative and DNA hypomethylation effects in plant cells
- 2017
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier. - 0981-9428 .- 1873-2690. ; 118, s. 551-560
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Tidskriftsartikel (refereegranskat)abstract
- The effects of nicotinamide (NIC) and its natural plant metabolites nicotinic acid (NIA) and trigonelline (TRIG) were studied with respect to defense in plant cell cultures. NIC and NIA could protect against oxidative stress damage caused by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH), which generates free radicals. Damage was analyzed as DNA strand breaks in cell cultures of Pisum sativum (garden pea), Daucus carota (carrot), Populus tremula L. × P. tremuloides (hybrid aspen) and Catharanthus roseus (Madagascar periwinkle), monitored by single cell gel electrophoresis (comet assay), and assays of cell leakage in C. roseus. The activities of aconitase and fumarase enzymes, which have key roles in energy metabolism, were analyzed in P. sativum cultures after treatment with NIC or NIA. Aconitase activity was increased by NIA, and fumarase activity was increased by both compounds. These compounds were shown to promote glutathione metabolism in P. sativum cultures, and NIC was shown to have a global DNA hypomethylating effect. Neither TRIG nor poly(ADP-ribose) polymerase (PARP) inhibitor 3-aminobenzamide offered any protection against DNA damage or cell leakage, nor did they promote aconitase or fumarase activities, or glutathione metabolism. By this broad approach addressing multiple biochemical factors and different plant species, we demonstrate that NIC and NIA protect plant cells from oxidative stress, and that NIC clearly exerts an epigenetic effect; decreased DNA methylation. This indicates that these compounds have important roles in the regulation of metabolism in plant cells, especially in connection to stress.
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| 6. |
- Björn, Lars Olof
(författare)
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On the history of phyto-photo UV science (not to be left in skoto toto and silence).
- 2015
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Ingår i: Plant Physiology and Biochemistry. - : Elsevier BV. - 1873-2690 .- 0981-9428. ; 93:Online 30 September 2014, s. 3-8
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Forskningsöversikt (refereegranskat)abstract
- This review of the history of ultraviolet photobiology focuses on the effects of UV-B (280-315 nm) radiation on terrestrial plants. It describes the early history of ultraviolet photobiology, the discovery of DNA as a major ultraviolet target and the discovery of photoreactivation and photolyases, and the later identification of Photosystem II as another important target for damage to plants by UV-B radiation. Some experimental techniques are briefly outlined. The insight that the ozone layer was thinning spurred the interest in physiological and ecological effects of UV-B radiation and resulted in an exponential increase over time in the number of publications and citations until 1998, at which time it was realized by the research community that the Montreal Protocol regulating the pollution of the atmosphere with ozone depleting substances was effective. From then on, the publication and citation rate has continued to rise exponentially, but with an abrupt change to lower exponents. We have now entered a phase when more emphasis is put on the "positive" effects of UV-B radiation, and with more emphasis on regulation than on damage and inhibition.
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| 7. |
- Braumann, Ilka, et al.
(författare)
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Reduced chlorophyll biosynthesis in heterozygous barley magnesium chelatase mutants
- 2014
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Ingår i: Plant Physiology and Biochemistry. - : Elsevier BV. - 1873-2690 .- 0981-9428. ; 78, s. 10-14
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Tidskriftsartikel (refereegranskat)abstract
- Chlorophyll biosynthesis is initiated by magnesium chelatase, an enzyme composed of three proteins, which catalyzes the insertion of Mg2+ into protoporphyrin IX to produce Mg-protoporphyrin IX. In barley (Hordeum vulgare L.) the three proteins are encoded by Xantha-f, Xantha-g and Xantha-h. Two of the gene products, XanH and XanG, belong to the structurally conserved family of AAA+ proteins (ATPases associated with various cellular activities) and form a complex involving six subunits of each protein. The complex functions as an ATP-fueled motor of the magnesium chelatase that uses XanF as substrate, which is the catalytic subunit responsible for the insertion of Mg2+ into protoporphyrin IX. Previous studies have shown that semi-dominant Xantha-h mutations result in non-functional XanH subunits that participate in the formation of inactive AAA complexes. In the present study, we identify severe mutations in the barley mutants xantha-h.38, -h.56 and -h.57. A truncated form of the protein is seen in xantha-h.38, whereas no XanH is detected in xantha-h.56 and -h.57. Heterozygous mutants show a reduction in chlorophyll content by 14-18% suggesting a slight semi-dominance of xantha-h.38, -h.56 and -h.57, which otherwise have been regarded as recessive mutations
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| 8. |
- Carlsson, Georg
(författare)
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Phosphorous deficiency decreases nitrogenase activity but increases proton efflux in N-2-fixing Medicago truncatula
- 2011
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Ingår i: Plant Physiology and Biochemistry. - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 49, s. 458-460
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Tidskriftsartikel (refereegranskat)abstract
- Effects of Sinorhizobium strain and P nutrition on N-2-dependent growth, nitrogenase activity and proton efflux by nodulated roots were investigated in the model legume Medicago truncatula cultivar Jemalong grown in hydroaeroponic culture in symbioses with Sinorhizobium meliloti strains 102F51 and 2011. Sinorhizobium strain had strong effects on nitrogenase activity and N-2-dependent growth, with S. meliloti 102F51 being the more efficient strain. Apparent and total nitrogenase activities, measured by hydrogen evolution in air and argon, respectively, were drastically reduced in plants supplied with 5 mu mol P plant(-1) week(-1) as compared with 15 mu mol P plant(-1) week(-1). There was a net proton efflux as soon as 2 weeks after inoculation and, in contrast to the effect of P nutrition on nitrogenase activity, P deficiency increased total and specific proton effluxes, irrespective of Sinorhizobium strain. (C) 2011 Elsevier Masson SAS. All rights reserved.
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| 9. |
- Christiernin, Maria
(författare)
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Lignin composition in cambial tissues of poplar
- 2006
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 44:11-12, s. 700-706
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Tidskriftsartikel (refereegranskat)abstract
- The cambial tissues of a Populus balsamifera, Balsam poplar clone were studied during a growth season. The Klason and acid-soluble lignin contents were determined as well as the carbohydrate monomer distribution and the protein content. Both the phloem and the xylem sides of the cambial region were examined. The samples were analyzed by thioacidolysis and structures of dimeric products were determined by mass spectrometry after desulphuration. Chemical analysis of samples during the growth season was combined with microscopy of embedded specimens that showed the state of cell differentiation at the time of sampling. In spring and early summer, growth is very rapid and the intention was to collect tissue in which exclusively the middle lamella/primary cell wall had begun to lignify. The Klason lignin, protein content and carbohydrate monomer distribution showed that all the specimens from the cambial tissues sampled during a growth season contained predominantly middle lamella and primary walls; except for the developing xylem sampled in August where the carbohydrate composition showed that secondary walls were present. Thioacidolysis showed that the lignin from the cambial tissues had more condensed structures than the lignin from the reference balsam poplar clone wood. More guaiacyl than syringyl units were detected and mass spectrometry showed that the cambial tissues contained more lignin structures with end-groups than the reference sample. These results suggest that lignification in the cambial layer and early developing xylem may take place predominantly in a bulk fashion during the summer. (c) 2006 Published by Elsevier Masson SAS.
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| 10. |
- Christiernin, Maria, et al.
(författare)
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Lignin isolated from primary walls of hybrid aspen cell cultures indicates significant differences in lignin structure between primary and secondary cell wall
- 2005
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 43:8, s. 777-785
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid aspen (Populus tremula x tremuloides) cell cultures were grown for 7, 14 and 21 days. The cell cultures formed primary cell walls but no secondary cell wall according to carbohydrate analysis and microscopic characterization. The primary walls were lignified, increasingly with age, according to Klason lignin analysis. Presence of lignin in the primary walls, with a higher content in 21-day old cells than in 7-day old cells, was further Supported by phloroglucinol/HCI reagent test and confocal microscopy after both immunolocalization and staining with acriflavin. Both laccase and peroxidase activity were found in the cultures and the activity increased during lignin formation. The lignin from the cell culture material was compared to lignin from mature aspen wood, where most of the lignin originates in the secondary cell wall, and which served as our secondary cell wall control. Lignin from the cell walls was isolated and characterized by thioacidolysis followed by gas chromatography and mass spectrometry. The lignin in the cell cultures differed from lignin of mature aspen wood in that it consisted exclusively of guaiacyl units, and had a more condensed structure. Five lignin structures were identified by mass spectrometry in the cell suspension cultures. The results indicate that the hybrid aspen cell culture used in this investigation may be a convenient experimental system for studies of primary cell wall lignin.
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