We quantified the physiological responses of black willow to four soil moisture regimes: no flooding (control, C), continuous flooding (CF), periodic flooding (PF), and periodic drought (PD). Stomatal limitation was one of the factors that led to the reduced photosynthetic capacity in CF cuttings. Under PD, stomatal closure, decreased leaf chlorophyll content, and increased dark fluorescence yield contributed to photosynthetic decline. CF cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by PD. PF cuttings tended to allocate more photoassimilates to root growth than to shoots. and S. Li ... [et al.].
a1_The halophytic C4 grass, Aeluropus littoralis, was cultivated under low (50 mM) and high (200 mM) NaCl salinity and inoculated with the arbuscular mycorrhizal fungi (AMF) Claroideoglomus etunicatum in a sand culture medium for 20 weeks. Shoot and root dry mass increased under salinity conditions up to 24 and 86%, respectively. Although the root colonization rate significantly decreased in the presence of salt, AMF-colonized (+AMF) plants had higher biomass compared with plants without AMF colonization (-AMF) only under saline conditions. Net CO2 assimilation rate increased significantly by both salinity levels despite stable stomatal opening. In contrast, AMF-mediated elevation of the net CO2 assimilation rate was associated with a higher stomatal conductance. Unexpectedly, leaf activity of phosphoenolpyruvate carboxylase decreased by salinity and AMF colonization. Transpiration rate was not affected by treatments resulting in higher water-use efficiency under salinity and AMF conditions. Concentrations of soluble sugars and free α-amino acids increased by both salinity and AMF treatments in the shoot but not in the roots. Proline concentration in the leaves was higher in the salt-treated plants, but AMF colonization did not affect it significantly. Leaf activity of nitrate reductase increased by both salinity and AMF treatments. Mycorrhizal plants had significantly higher Na+ and K+ uptake, while Ca2+ uptake was not affected by salt or AMF colonization. The ratio of K+/Na+ increased by AMF in the shoot while it decreased in the roots. Leaf osmotic potential was lowered under salinity in both +AMF and -AMF plants. Our results indicated that higher dry matter production in the presence of salt and AMF could be attributed to higher CO2 and nitrate assimilation rates in the leaves., a2_Higher leaf accumulation of soluble sugars and α-amino acids but not proline and elevated water-use efficiency were associated with the improved growth of A. littoralis inoculated with AMF., R. Hajiboland, F. Dashtebani, N. Aliasgharzad., and Obsahuje seznam literatury
Macroalgae must be able to survive in conditions of different light intensities with no damage to their physiological performance or vital processes. Irradiance can stimulate the biosynthesis of certain photoprotective compounds of biotechnological interest, such as pigments and proteins. Pterocladiella capillacea is a shade-grown alga, which play a role key in the balance of marine ecosystems. In addition, it is considered one of the best sources of bacteriological agar and agarose with a wide pharmacological potential. In order to evaluate the photosensitivity in P. capillacea under 60 (control) and moderate light intensity of 300 μmol(photon) m-2 s-1, photosynthetic performance and chemical composition were assessed. P. capillacea showed photosensitivity without evidence of photodamage. The results indicate the possibility to increase a growth rate and probably infer productivity in long-term cultivation by stimulation at moderate light intensity. Increasing photosynthetic pigment and protein contents were also observed under medium light, an interesting result for functional ingredient approaches., T. B. Harb, A. Nardelli, F. Chow., and Obsahuje bibliografii
Since 2002, Silver buffaloberry (Shepherdia argentea) has been introduced from North America in order to improve the fragile ecological environment in western China. To elucidate the
salt-resistance mechanism of S. argentea, we conducted a test with two-year-old seedlings subjected to 0, 200, 400, and 600 mM NaCl solutions for 30 d. The results showed that significant salt-induced suppression of plant fresh mass (FM) and stem height of S. argentea seedlings occurred only at the highest salinity level (600 mM). Leaf number, plant dry mass (DM), and chlorophyll (Chl) content declined markedly at both 400 and 600 mM. Leaf area (LA) and leaf water potential (Ψw) continuously declined with the increase of salinity. There was also a progressive and evident decrease in net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (gs) with the increase of salinity and time. The correlation analysis indicated that PN was positively correlated with gs at all salinity levels while correlated with intercellular CO2 concentration (Ci) only at moderate salinity levels (<600 mM). Based on the initial slope of the PN/Ci curves, the estimated carboxylation efficiency (CE) was strongly inhibited at 600 mM. We confirm that S. argentea is highly tolerant to salinity. Moreover, our results show that at moderate salinity levels, salt-induced inhibition of photosynthesis is mainly attributed to the stomatal efficient closure predetermined by a low water potential in leaves; while at the high salinity levels, the inhibition is mainly due to the suppression of chloroplast capacity to fix CO2 caused by the serious decline in both CE and Chl contents. and J. Qin ... [et al.].
A brief pulse' of red (R) radiatíon increased actívity and protein content of phosphoenolpyruvate carboxylase (PEPC): diis increase was inhibited by cycloheximide. The efifect of R was far-red pulse (FR) reversible when R was followed inunediately (but not after 24 h) by FR. Thus phytochrome was involved in PEPC regulatíon in etiolated maize leaves. Both a lag phase and a saturation exist in the process of R induction of PEPC synthesis: the highest PEPC acitívity was obtained 24 h after R. Etiolated maize leaves of different age showed different sensitivity to R: the highest sensitivity was found in 5 d-old seedlings. 5 min of R was sufficient for inducing PEPC synthesis, and no additíonal increases were obtained in actívity and protein content of PEPC when the R tíme was prolonged.
The Chemical weed control should apply herbicides which interfere only with the plant-specific processes, like photosynthesis, biosynthesis of pigments or essential amino acids. Accordingly, attention for herbicide development is focused on the chloroplast as a typical plant organelle. This páper reports on the mode of action of so-called bleaching compounds which affect the biosynthesis of carotenoids and chlorophylls, respectively, causing interrupted build-up or degradation of the photosynthetic apparatus. In the first čase such inhibitors lead to accumulation of precursors of P-carotene and xanthophylls, which cannot protéct chlorophyll (Chl) against the photooxidation. Herbicidal inhibitors of Chl biosynthesis result in accumulation of protoporphyrin IX which is sensitised by light thereby inducing radical peroxidative reactions. The peroxidative stress can - under certain circumstances - be counteracted by the antioxidative systém of the plant cell. Basic biochemical studies and molecular genetics in this field of herbicidal inhibitors research are briefly outlined.
The present study was conducted to examine changes in photosynthetic pigment composition and functional state of the thylakoid membranes during the individual steps of preparation of samples that are intended for a separation of pigmentprotein complexes by nondenaturing polyacrylamide gel electrophoresis. The thylakoid membranes were isolated from barley leaves (Hordeum vulgare L.) grown under low irradiance (50 μmol m-2 s-1). Functional state of the thylakoid membrane preparations was evaluated by determination of the maximal photochemical efficiency of photosystem (PS) II (FV/FM) and by analysis of excitation and emission spectra of chlorophyll a (Chl a) fluorescence at 77 K. All measurements were done at three phases of preparation of the samples: (1) in the suspensions of osmotically-shocked broken chloroplasts, (2) thylakoid membranes in extraction buffer containing Tris, glycine, and glycerol and (3) thylakoid membranes solubilized with a detergent decyl-β-D-maltosid. FV/FM was reduced from 0.815 in the first step to 0.723 in the second step and to values close to zero in solubilized membranes. Pigment composition was not pronouncedly changed during preparation of the thylakoid membrane samples. Isolation of thylakoid membranes affected the efficiency of excitation energy transfer within PSII complexes only slightly. Emission and excitation fluorescence spectra of the solubilized membranes resemble spectra of trimers of PSII light-harvesting complexes (LHCII). Despite a disrupted excitation energy transfer from LHCII to PSII antenna core in solubilized membranes, energy transfer from Chl b and carotenoids to emission forms of Chl a within LHCII trimers remained effective. and V. Karlický ... [et al.].
During the vegetation period from June to October 1990 the growth, photosynthetic C02-fixation, pigment content and chlorophyll (Chl) fluorescence characteristics were compared in the needles of 5-year-old spruce dones Picea abies (L.) Karst., cultivated for two years on the soil and the sand, with or without addition of minerál fertilizers. Minerál deflciency in the spruce dones grown on the sand instead of a humus containing soil resulted in somewhat reduced lengthwise growth of shoots and needles, lower level of Chl and carotenoids (Car), as well as lower net photosynthetic rates (F^) per needle area unit and in generál also lower stomata conductance (gH2o) values. In contrast, the variable Chl fluorescence measured via the Chl fluorescence decrease ratio (Rfj = fd/fs) was only little affected, indicating an intemal íunctional photosynthetic apparatus even under minerál deflciency with a lower Chl content. In fact, Fj,} expressed on Chl basis was even signiflcantly higher in the newly developed 1990 needles of the sand cultures than in the soil ones. Application of a forestry fertilizer with basic minerals (K, Ca, Mg and some N) to the sand cultures increased growth of shoots and needles, levels of Chl and Čar, F^ and stomata conductance, and decreased the Chl fluorescence ratio F690/F735 and lability of the photosynthetic apparatus, as also seen in increased values of the ratio Chl/Car (a+b/x+c). The hasič minerál elements are thus necessaiy for the photosynthetic apparatus development, as well as stability of its pigment content and physiological function.
The review is done to summarise the history of the discoveries of the many anatomical, agronomical, and physiological aspects of C4 photosynthesis (where the first chemical products of CO2 fixation in illuminated leaves are four-carbon dicarboxylic acids) and to document correctly the scientists at the University of Arizona and the University of California, Davis, who made these early discoveries. The findings were milestones in plant science that occurred shortly after the biochemical pathway of C3 photosynthesis in green algae (where the first chemical product is a three-carbon compound) was elucidated at the University of California, Berkeley, and earned a Nobel Prize in chemistry. These remarkable achievements were the result of ground-breaking pioneering research efforts carried out by many agronomists, plant physiologists and biochemists in several laboratories, particularly in the USA. Numerous reviews and books written in the past four decades on the history of C4 photosynthesis have focused on the biochemical aspects and give an unbalanced history of the multidisciplinary/multinstitutional nature of the achievements made by agronomists, who published much of their work in Crop Science. Most notable among the characteristics of the C4 species that differentiated them from the C3 ones are: (I) high optimum temperature and high irradiance saturation for maximum leaf photosynthetic rates; (II) apparent lack of CO2 release in a rapid stream of CO2-free air in illuminated leaves in varying temperatures and high irradiances; (III) a very low CO2 compensation point; (IV) lower mesophyll resistances to CO2 diffusion coupled with higher stomatal resistances, and, hence, higher instantaneous leaf water use efficiency; (V) the existence of the so-called "Kranz leaf anatomy" and the higher internal exposed mesophyll surface area per cell volume; and (VI) the ability to recycle respiratory CO2 by illuminated leaves.
This study draws attention to new facts coming out of the scribal colophons of a manuscript miscellany held by the St. James Parsonage Library in Brno and it completes curriculum vitae of Martin of Tišnov who used to be known as a scribe of manuscripts and the author of two Latin panegyrics. He is documented as a parson in Sebranice in the Blansko region at least in the years 1475-1483. He was in connection with the important family of noblemen of Boskovice for a long time. For the time being, however, we are not sure if he can be identified with the printer Martin of Tišnov who edited a Czech Bible in Kutná Hora in 1489 an who also edited the two earliest Prague prints in 1478.