The DF III 1 Strahov Manuscript, which preserves the only version of the Vincencius and Jarloch chronicle, has a rich and not too happy history behind it. For a long time it was housed in the Prague Chapter Library, from which it was lost under mysterious circumstances sometime before 1764. It was not discovered again until 1826 by Josef Dietrich, curate at Postoloprty, who donated it to Josef Dobrovský. Dobrovský used it for his edition of what is known as the Ansbert Chronicle and then donated it to the Strahov Monastery Library. If we follow the fortunes of the Codex before its disappearance from the Chapter Library, we find that this evidently happened "thanks" to Václav Prokop Duchovský, Secretary to the Archbishop's Consistory, who did not return the borrowed manuscript to its original place, and kept this fact from Gelasius Dobner, who was looking for the Codex in the library a year later in order to compile an edition of both chronicles. The motive for this behaviour was evidently their mutual poor relations due to Dobner's criticism of Hájek's Chronicle.
We investigated the effect of large isoform of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activase (RuBPCO-A) on photosynthesis and constructed two plant expression vectors and introduced them into rice cultivars (Oryza sativa f. japonica cv. Nipponbare) through Agrobacterium tumefaciens-mediated transformation. Plasmid pCBrbcSRca contained the cDNA of RuBPCO-A large isoform (rca) controlled by RuBPCO small subunit gene promoter (rbcS), and plasmid pCBUbi-antirca contained a reversed rca sequence driven by maize ubiquitin promoter. Transformants were screened by polymerase chain reaction (PCR), Southern and Western blot analysis. Compared to the control rice plants, RuBPCO activity was improved in the pCBrbcSRca rice plants, which is opposite to RuBPCO activity in the pCBUbi-antirca rice plants. Net photosynthetic rate, quantum yield of electron transport in photosystem 2, and steady state photochemical fluorescence quenching increased in the pCBrbcSRca plants, but decreased in the pCBUbi-antirca plants as compared to the controls. The pCBrbcSRca plants had heavier grains and accelerated development, while the pCBUbi-antirca plants showed reverse changes. Thus RuBPCO-A large isoform exerts considerable effect on photosynthesis and is a promising target for plant breeding to improve rice crop yield. and H. R. Wu ... [et al.].
To investigate the role of glycine betaine in photosynthesis under stress, a transgenic wheat (Triticum aestivum L.) line T6 overaccumulating glycine betaine and its wild type Shi4185 were used. Seedlings were exposed to conditions of drought (30%, PEG-6000), heat (40°C) and their combination. The results revealed ultrastructural damage to the chloroplast and thylakoid lamellae with the withered phenotype by both drought and heat stress, and the damage was exacerbated by the combination of drought and heat. The appearance of a K step in the typical O-J-I-P curve and the decrease of Hill activity indicated a reduction of oxygen evolving complex function caused by stress. The greater damage was found in wild type than T6. Overaccumulation of glycine betaine in T6 could protect lipids in the thylakoid membrane from damage and stabilize the index of unsaturated fatty acids under stress. A lower ratio of monogalactosyl diacylglycerol/digalactosyl diacylglycerol and higher phosphatidylglycerol content in the thylakoid membrane of T6 were also observed under stress. These effects can promote stability of the thylakoid membrane. Otherwise, glycine betaine overaccumulation decreased photoinhibition of PSII under stress. The results also suggest that xanthophyll cycle-dependent non-radiative energy dissipation may be involved in the GB-mediated effects on PSII function under stress conditions. and G. P. Wang ... [et al.].
We investigated the different responses of wheat (Triticum aestivum L.) plants to drought- (DS) and heat stress (HS), and analyzed the physiological mechanisms of glycine betaine (GB) involved in the improvement of wheat tolerance to the combination of these stresses. The transgenic wheat T6 line was generated by introducing a gene encoding betaine aldehyde dehydrogenase (BADH) into the wild-type (WT) Shi4185 line. The gene was cloned from the Garden Orache plant (Atriplex hortensis L.). Wheat seedlings were subjected to drought stress (30%, PEG-6000), heat stress (40°C), and their combination. Photosynthetic gas exchange, water status and lipid peroxidation of wheat leaves were examined under different stresses. When subjected to a combination of drought and heat, the inhibition of photosynthesis was significantly increased compared to that under DS or HS alone. The increased inhibition of photosynthesis by the combined stresses was not simply the additive stress effect of separate heat- and drought treatments; different responses in plant physiology to DS and HS were also found. HS decreased the chlorophyll (Chl) content, net photosynthetic rate (PN), carboxylation efficiency (CE) and apparent quantum yield (AQY) more than DS but DS decreased the transpiration rate (E), stomata conductance (gs) and intercellular CO2 concentration (Ci) more than HS. GB over-accumulation led to increased photosynthesis not only under individual DS or HS but also under their combination. The enhancement of antioxidant activity and the improvement of water status may be the mechanisms underlying the improvement of photosynthesis by GB in wheat plants. and G. P. Wang ... [et al.].
Calmodulin (CaM) is a highly conserved calcium sensor protein associated with chilling tolerance in living organisms. It has four EF-hand domains for binding of four Ca2+, two of them located in the N-terminus, and the other two in the C-terminus. A notothenioid CaM gene fragment (CaMm), which only codes for N-terminus of CaM (with two EF-hand domains), was introduced into Nicotiana benthamiana. Effects of its overexpression on chilling tolerance in plants were explored. During 4◦C or 0◦C chilling treatment, both CaMm and CaM transgenic plants showed higher PSII maximum quantum yield, actual quantum yield, and soluble protein content, lower electrolyte leakage and malondialdehyde content than that of the control. The changes in these physiological indices were comparable between the CaMm and CaM transgenic plants during the treatments. These results indicate that the N-terminus of calmodulin is likely the key functional domain involved in the adaptive response to cold stress., T. J. Zhang, L. J. Pan, Q. Huang, L. H. Zhu, N. Yang, C. L. Peng, L. B. Chen., and Obsahuje seznam literatury
Drought impacts severely crop photosynthesis and productivity. Development of transgenic rice overexpressing maize phosphoenolpyruvate carboxylase (PEPC) is a promising strategy for improving crop production under drought stress. However, the molecular mechanisms of protection from PEPC are not yet clear. The objective of this study was: first, to characterize the response of individual photosynthetic components to drought stress; second, to study the physiological and molecular mechanisms underlying the drought tolerance of transgenic rice (cv. Kitaake) over-expressing maize PEPC. Our results showed that PEPC overexpressing improved the ability of transgenic rice to conserve water and pigments during drying as compared to wild type. Despite the fact that drought induced reactive oxygen species and damaged photosystems (especially, PSI) in both lines, higher intercellular CO2 concentration protected the photosynthetic complexes, peptides, and also ultrastructure of thylakoid membranes against the oxidative damage in transgenic rice. In conclusion, although photosynthetic apparatus suffered an inevitable and asymmetric impairment during drought conditions, PEPC effectively alleviated the oxidative damage on photosystems and enhanced the drought tolerance by increasing intercellular CO2 concentration. Our investigation provided critical clues for exploring the feasibility of using C4 photosynthesis to increase the yield of rice under the aggravated global warming., W. J. Shen, G. X. Chen, J. G. Xu, Y. Jiang, L. Liu, Z. P. Gao, J. Ma, X. Chen, T. H. Chen, and C. F. Lv., and Obsahuje seznam literatury
In transgenic (TG) tomato (Lycopersicon esculentum Mill.) overexpressed ω-3 fatty acid desaturase gene (LeFAD7) was identified, which was controlled by the cauliflower mosaic virus 35S promoter and induced increased contents of unsaturated fatty acids in thylakoid membrane. Under chilling stress at low irradiance (4 °C, 100 µmol m-2 s-1) TG plants with higher linolenic acids (18: 3) content maintained a higher O2 evolution rate, oxidizable P700 content, and maximal photochemical efficiency (Fv/Fm) than wild type (WT) plants. Low temperature treatment for 6 h resulted in extensive changes of chloroplast ultrastructure: in WT plants most chloroplasts became circular, the number of amyloids increased, appressed granum stacks were dissolved, grana disappeared, and the number of grana decreased, while only a few grana were found in leaves of TG plants. Hence the overexpression of LeFAD7 could increase the content of
18 : 3 in thylakoid membrane, and this increase alleviated the photoinhibition of photosystem (PS) 1 and PS2 under chilling at low irradiance. and X.-Y. Liu ... [et al.].
Employing the non-invasive techniques of infra-red gas analysis and pulse amplitude modulated chlorophyll fluorometry, we determined the partitioning of photosynthetic electrons between photosynthetic carbon reduction and other reductive processes resulting in the formation of active oxygen species (AOS) in intact green leaves. This we studied in plant species that are adapted to two different agro-climatic conditions, namely the warm plains (76°36'E, 9°32'N) and the cool mountains (1 600 m a.s.l.) in the south Indian state of Kerala. Ground frost and low temperature were more harmful to those species adapted to the warm plains than the ones adapted to the cool mountains. Exposure to low temperature decreased leaf photosynthetic carbon assimilation rates and quantum yield of photochemical activity in species naturally adapted to the warm plains. High irradiances further aggravated the harmful effects of low temperature stress possibly by overproducing AOS. This resulted in severe peroxidative damage as inferred by the accumulation of malondialdehyde (MDA) in the leaves. and B. Alam, J. Jacob.