In the present study, the physiological efficiencies of 181 mini-core peanut accessions (genotypes) were evaluated according to variability in their physiological performance in the field during summer (2012). Genotypes were categorized into groups of high, medium, and low physiological activity. Thirty-four genotypes showed high net photosynthetic rate (PN > 33 μmol m-2 s-1), 28 genotypes exhibited high stomatal conductance (gs > 0.54 mmol m-2 s-1), 33 genotypes manifested high transpiration rate (E > 11.8 mmol m-2 s-1), 30 genotypes performed with high water-use efficiency (WUE > 3.8), 30 genotypes reached high chlorophyll SPAD values (SCMR > 40), and 35 genotypes showed high maximum quantum yield of PSII (Fv/Fm > 0.86). In addition, few genotypes showed high values for multiple physiological traits. A total of 54 genotypes exhibited higher values in two, 20 genotypes showed a high value in three, and in eight genotypes, high values occurred in four different physiological traits. Interestingly, only two genotypes, NRCG 14493 and 14507, showed high values for five different traits. Positive correlation was observed between gs and PN, E, and gs, and between PN and Fv/Fm, while WUE and E showed a negative correlation. The genotypes with high PN, gs, and WUE coupled with high SCMR and Fv/Fm could be used in peanut crop improvement programme for yield enhancement as well as stress tolerance., A. L. Singh, R. N. Nakar, K. Chakraborty, K. A. Kalariya., and Obsahuje bibliografii
In the phytotron experiment, the effect of elevated atmospheric CO2 (EC, 750 μmol mol-1) on the drought tolerance was studied in two winter varieties (Mv Mambo, tolerant; Mv Regiment, moderately tolerant) and in one spring variety of wheat (Lona, sensitive to drought). Changes in net photosynthetic rate (P N), stomatal conductance, transpiration, wateruse efficiency, effective quantum yield of photosystem II, and activities of glutathione reductase (GR), glutathione-Stransferase (GST), guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were monitored during water withdrawal. Drought caused a faster decline of PN at EC, leading to the lower assimilation rates under severe drought compared with ambient CO2 (NC). In the sensitive variety, PN remained high for a longer period at EC. The growth at EC resulted in a more relaxed activation level of the antioxidant enzyme system in all three varieties, with very low activities of GR, GST, APX, and POD. The similar, low values were due to decreases in the varieties which had higher ambient values. A parallel increase of CAT was, however, recorded in two varieties. As the decline in PN was faster at EC under drought but there was no change in the rate of electron transport compared to NC values, a higher level of oxidative stress was induced. This triggered a more pronounced, general response in the antioxidant enzyme system at EC, leading to very high activities of APX, CAT, and GST in all three varieties. The results indicated that EC had generally favourable effects on the development and stress tolerance of plants, although bigger foliage made the plants more prone to the water loss. The relaxation of the defence mechanisms increased potentially the risk of damage due to the higher level of oxidative stress at EC under severe drought compared with NC., S. Bencze, Z. Bamberger, T. Janda, K. Balla, B. Varga, Z. Bedõ, O. Veisz., and Obsahuje bibliografii
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
Permanent plastid-nuclear complexes (PNCs) exist in tobacco cells from their mitosis up to programmed cell death (PCD). PNCs in senescing cells of tobacco leaves were typical by enclosure of peroxisomes and mitochondria among chloroplasts which were in contact with nucleus. Such a complex position provides simultaneous interaction of these organelles and direct regulation of metabolism and PCD avoiding the cytosol. and T. Selga, M. Selga, A. Ozoliņa.
The aim of our study was to answer whether any positive correlation exists between K+ uptake and salt tolerance in wheat. We carried out a sand-culture experiment with salt-tolerant, DK961 (ST), and salt-sensitive, JN17 (SS), wheat cultivars, where photosynthesis, the K+/Na+ ratio, growth, and the biomass yield were examined. The seeds were exposed for four weeks to six NaCl concentrations (50, 100, 150, 200, 250, and 300 mM), which were embodied in the Hoagland solution. Salinity-induced decrease of K+ or increase in the Na+ content was much smaller in ST than that in SS. The reductions in the light-saturated photosynthetic rate (P Nmax) and chlorophyll content caused by salinity were smaller in the ST compared to SS. Stomatal conductance decreased in both cultivars under saline conditions; nevertheless, it was lower in SS than in ST. The antioxidative capacity was higher in ST than that in SS under saline conditions. Significant positive correlations were observed in both cultivars between K+ contents and P Nmax/biomass yields. We suggest that higher-affinity K+ uptake might play a key role in higher salt tolerance and it might be a reliable indicator for breeding new species of salt-tolerant wheat., D. Cheng, G. Wu, Y. Zheng., and Obsahuje seznam literatury
Previously, our data indicated that both cAMP and MAP kinase signaling play important roles in microalgal physiology as well as in lipid or carotenoid biosynthesis. In order to understand downstream genes of these signaling pathways, we employed proteomics approach. Both signal pathways were first altered with specific signaling inhibitors or modulators. Treatment of specific inhibitors changed microalgal size and increased lipid contents. With the microalgal cells after treatments of specific signaling inhibitor or modulators, we performed the proteomics analysis to identify downstream genes responsible for these phenotypes. Interestingly, multiple photosynthesis genes were identified, particularly proteins associated with PSII. Our data suggested that MAP kinase and cAMP signaling affect the photosynthesis, thereby leading to microalgal lipid or carotenoid biosynthesis., C. Lee, J.-K. Rhee, D. G. Kim, Y.-E. Choi., and Obsahuje seznam literatury
The aim of our study was to investigate the role of protons in regulating energy distribution between the two photosystems in the thylakoid membranes. Low pH-induced changes were monitored in the presence of a proton blocker, N,N′-dicyclohexylcarbodiimide (DCCD). When thylakoid membranes were suspended in a low-pH reaction mixture and incubated with DCCD, then a decrease in the fluorescence intensity of photosystem II (PSII) was observed, while no change in the intensity of photosystem I (PSI) fluorescence occurred according to the measured fluorescence emission spectra at 77 K. Since low pH induced distribution of energy from PSII to PSI was inhibited in the presence of DCCD, we concluded that pH/proton concentration of the thylakoid membranes plays an important role in regulating the distribution of the absorbed excitation energy between both photosystems., T. Tongra, S. Bharti, A. Jajoo., and Obsahuje bibliografii
PsbP is an extrinsic protein of PSII having a function of Ca2+ and Cl- retention in the water-oxidizing center (WOC). In order to understand the mechanism how PsbP regulates the Cl- binding in WOC, we examined the effect of PsbP depletion on the protein structures around the Cl- sites using Fourier transform infrared (FTIR) spectroscopy. Light-induced FTIR difference spectra upon the S1-S2 transition were obtained using Cl--bound and NO3--substituted PSII membranes in the presence and absence of PsbP. A clear difference in the amide I band changes by PsbP depletion was observed between Cl--bound and NO3--substituted PSII samples, indicating that PsbP binding perturbed the protein conformations around the Cl-ion(s) in WOC. It is suggested that PsbP stabilizes the Cl- binding by regulating the dissociation constant of Cl- and/or an energy barrier of Cl- dissociation through protein conformational changes around the Cl- ion(s)., J. Kondo, T. Noguchi., and Obsahuje bibliografické odkazy