5-aminolevulinic acid (ALA) is an essential precursor for the biosynthesis of tetrapyrrols such as heme and chlorophyll (Chl). Previous studies have focused mainly on promotive effects of exogenous ALA on plant growth, while regulatory mechanisms affecting Chl biosynthesis have been only partially discussed. In the present study, the ameliorative role of exogenous ALA was investigated on Chl and endogenous ALA biosynthesis in six-day-old etiolated oilseed rape (Brassica napus L.) cotyledons during the de-etiolation stage. We showed that exogenously applied ALA of a low dosage enhanced Chl and ALA accumulation in cotyledons, while 600 µM ALA treatment inhibited the accumulation of Chl and ALA severely. However, the gene expression levels of glutamyl-tRNA reductase (HEMA) and glutamate-1-semialdehyde aminotransferase (GSA) were not affected under either low or high ALA concentrations. Furthermore, water deficit induced by polyethylene glycol 6000 (PEG) suppressed the Chl and ALA accumulation in cotyledons, while the inhibition was partially alleviated in the cotyledons pretreated with ALA. The decrease in Chl biosynthesis induced by PEG stress was assumed to be related to downregulation of HEMA and Mg-chelatase ChlH (ChlH), and upregulation of ferrochelatase (FC) genes. Moreover, exogenously applied ALA did not show any effect on the expression of Chl synthesis-related genes under the PEG treatment. These results showed a difference in suppressing ALA synthesis due to the high concentration of ALA and PEG. Exogenously applied ALA did not affect the expression of HEMA and GSA, thus exogenous ALA regulated Chl synthesis not via the regulation of transcriptional level in ALA biosynthesis. However, the inhibition in Chl and endogenous ALA accumulation by the PEG treatment may be attributed to downregulation of HEMA and ChlH, and upregulation of FC., D. Liu, D. D. Kong, X. K. Fu, B. Ali, L. Xu, W. J. Zhou., and Seznam literatury
The effects of polyamines (PAs) on salt stress in Bakraii (Citrus reticulata × Citrus limetta) seedlings were studied. Foliar treatments by putrescine (Put), spermidine (Spd), and spermine (Spm) (0, 0.5, and 1 mM) were applied during the salinity period
(0 and 75 mM of NaCl). PA-treated seedlings showed a lower content of Na+ and Cl- in leaves. Application of PAs increased net photosynthetic rate in salt-stressed plants and it contributed to the enhanced growth parameters. PAs application considerably induced growth improvement in Bakraii seedlings which was found to be associated with reduced electrolyte leakage, increased relative water content, chlorophyll fluorescence parameters, activities of key antioxidant enzymes, as well as increased photosynthetic pigment concentration under saline regime. These results showed the promising use of PAs, especially of Spd and Spm, for reducing the negative effects of salinity stress and improving the growth of citrus seedlings., D. Khoshbakht, M. R. Asghari, M. Haghighi., and Obsahuje bibliografii
Salicylic acid (SA) is a common, plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. Our experiment was therefore conducted to test whether the application of SA at various concentrations (0, 0.10, 0.50, and 1.00 mM) as a foliar spray would protect citrus seedlings (Valencia orange/Bakraii) subjected to salt stress (0, 25, 50, and 75 mM NaCl). Growth parameters, leaf chlorophyll (Chl) content, relative water content (RWC), maximal quantum yield of PSII photochemistry (Fv/Fm), and gas-exchange variables were negatively affected by salinity. In addition, leaf electrolyte leakage (EL) and proline content increased by salinity treatments. Application of SA increased net photosynthetic rate and proline content in salt stressed plants and may have contributed to the enhanced growth parameters. SA treated plants had greater Chl content and RWC compared with untreated plants when exposed to salt stress. Fv/Fm ratio and stomatal conductance were also significantly higher in SA treated plants under saline stress conditions. SA application reduced EL compared to untreated plants, indicating possible protection of integrity of the cellular membrane. It appeared that the best ameliorative remedies of SA were obtained when Valencia orange/Bakraii seedlings were sprayed by 0.50 and 1.00 mM solutions. Overall, the adverse effects of salt stress could be alleviated by exogenous application of SA., D. Khoshbakht, M. R. Asgharei., and Obsahuje seznam literatury
A greenhouse experiment was conducted to examine the effect of foliar application of triacontanol (TRIA) on two cultivars (cv. S-24 and MH-97) of wheat (Triticum aestivum L.) at different growth stages. Plants were grown in full strength Hoagland’s nutrient solution under salt stress (150 mM NaCl) or control (0 mM NaCl) conditions. Three TRIA concentrations (0, 10, and 20 μM) were sprayed over leaves at three different growth stages, i.e. vegetative (V), boot (B), and vegetative + boot (VB) stages (two sprays on same plants, i.e., the first at 30-d-old plants and the second 78-d-old plants). Salt stress decreased significantly growth, net photosynthetic rate (PN), transpiration rate (E), chlorophyll contents (Chl a and b), and electron transport rate (ETR), while membrane permeability increased in both wheat cultivars. Stomatal conductance (gs) decreased only in salt-sensitive cv. MH-97 under saline conditions. Foliar application of TRIA at different growth stages enhanced significantly the growth, PN, gs, Chl a and b contents, and ETR, while membrane permeability was reduced in both cultivars under salt stress. Of various growth stages, foliar-applied TRIA was comparatively more effective when it was applied at V and VB stages. Overall, 10 μM TRIA concentration was the most efficient in reducing negative effects of salinity stress in both wheat cultivars. The cv. S-24 showed the better growth and ETR, while cv. MH-97 exhibited higher nonphotochemical quenching. and S. Perveen, M. Shahbaz, M. Ashraf.
Influence of different phosphorus concentrations was studied in four rice varieties (Akhanphou, MTU1010, RP BIO 226, and Swarna) differing in their tolerance to low phosphorus. There was an increase in shoot and root dry mass with the increase in phosphorus concentration. At the low phosphorus concentration at both tillering and reproductive stages, Swarna, followed by Akhanphou, recorded maximum biomass for both roots and shoots, while the minimum was observed in RP BIO 226. Reduction in photosynthetic rate, stomatal conductance, transpiration rate, and internal CO2 concentration at low phosphorus concentrations were observed at both tillering and reproductive stages in all the genotypes. In low phosphorus, maximum photosynthetic rate was found in Swarna followed by Akhanphou. Phosphorus deficiency did not alter the maximum efficiency of PSII photochemistry, however, there was a reduction in effective PSII quantum yield, electron transport rate, and coefficient of photochemical quenching, while the coefficient of nonphotochemical quenching was higher in the low phosphorus-treated plants. Prolonged exposure to excessive energy and failure to utilize the energy in carbon-reduction cycle induced the generation of reactive oxygen species, which affected PSII as indicated by the fluorescence traits. The reduction was less severe in case of Swarna and Akhanphou. The activities of superoxide dismutase, peroxidase, and catalase increased in roots under low phosphorus concentration indicating that photoprotective mechanisms have been initiated in rice plants in response to phosphorus deficiency. Comparatively, Swarna and Akhanphou exhibited a higher biomass, higher photosynthetic rate, and better reactive oxygen species-scavenging ability which conferred tolerance under low phosphorus conditions., N. Veronica, D. Subrahmanyam, T. Vishnu Kiran, P. Yugandhar, V. P. Bhadana, V. Padma, G. Jayasree, S. R. Voleti., and Obsahuje bibliografii
Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) is sold commercially as a biocontrol agent of filth flies, including the house fly, Musca domestica L. (Diptera: Muscidae). For this reason, S. cameroni is mass-reared for inundative releases to control harmful flies. However, the mass-rearing protocols include very little information on the influence of natal host on subsequent host selection by parasitoids with more than one potential host as in the genus Spalangia. Here, we report on the use of S. cameroni against M. domestica. The S. cameroni were reared using Ceratitis capitata Wiedemann (Diptera: Tephritidae) (natal host) pupae for several generations. Freeze-killed fly pupae were used in assays to determine the fecundity, number of adult progeny and sex-ratio of this parasitoid. Realized fecundity and number of adult progeny were greater when provided with house fly pupae than Mediterranean fruit fly pupae. Thus S. cameroni parasitized more house fly pupae than C. capitata pupae, even though the parasitoid was reared on Mediterranean fruit fly for many generations. These results indicate that S. cameroni reared on C. capitata can be successfully used in inundative releases against both fruit flies (agriculture) and house flies (livestock farming)., Francisco Beitia, Erik Valencia, Bernat Peris, Luis De Pedro, Josep D. Asís, José Tormos., and Obsahuje bibliografii
The steady-state oxygen evolution rate was previously shown to be stimulated by the disaccharide trehalose in PSII suspension. Here we showed a similar increase in the rate of oxygen evolution in PSII core complexes from spinach in solution and in proteoliposomes in the presence of trehalose. Using direct electrometrical technique, we also revealed that trehalose had no effect on the kinetics of electron transfer from Mn to redox-active-tyrosyl radical, YZ (S1 - S2 transition), while it accelerated the kinetics of electrogenic proton transport during S2 - S3 and S4 - S0 transitions of the wateroxidizing complex (WOC) induced by the first, second, and third laser flashes in dark-adapted PSII samples. These observations imply that the effect of trehalose occurrs due to its interaction with the WOC., M. D. Mamedov, E. S. Nosikova, L. A. Vitukhnovskaya, A. A. Zaspa, A. Yu. Semenov., and Obsahuje bibliografické odkazy
Leaf senescence can be induced by numerous factors. In order to explore the relationship between root respiration and leaf senescence, we utilized different types of phloem girdling to control the root respiration of Alhagi sparsifolia and its physiological response. Our results showed that both girdling and inhibition of root respiration led to a decline of stomatal conductance, photosynthesis, transpiration rate, chlorophyll (Chl) a, Chl b, carotenoid (Car) content, Chl a/b, Chl/Car, water potential, and Chl a fluorescence, as well as to an increase of abscisic acid (ABA), proline, and malondialdehyde content in leaves and to upregulation of senescence-associated gene expression. Our present work implied that both inhibition of root respiration and girdling can induce leaf senescence. In comparison with phloem girdling, the leaf senescence caused by inhibition of root respiration was less significant. The reason for girdling-induced senescence was ABA and carbohydrate accumulation. Senescence induced by inhibition of root respiration occurred due to leaf water stress resulting from inhibition of water absorption., G.-L. Tang, X.-Y. Li, L.-S. Lin, Y. Hu, F.-J. Zeng., and Obsahuje seznam literatury
Vitamin D status and the relationship between serum 25(OH) vitamin D concentrations and the components of insulin resistance were examined in 120 patients with chronic kidney disease stage 2 and 3. Insulin sensitivity/resistance was calculated by the quantitative insulin sensitivity check index (QUICKI). In this analysis, the prevalence of insulin resistance was 42 %. Only 17 % of patients had serum 25(OH) vitamin D concentration in the recommended range ( ≥ 30 ng/ml), 42 % suffered from vitamin D insufficiency and 41 % had moderate vitamin D deficiency. Insulin resistance significantly correlated with serum 25(OH)D and 1,25(OH) 2 D concentrations, renal function and protein excretion rate. Our results support the increasing evidence that vitamin D deficiency may be one of the factors participating in the development of insulin resistance already in the early stages of chronic kidney disease. and K. Štefíková ... [et al.].
Environmental stresses, such as cold, heat, salinity, and drought, induce ethylene production and oxidative stress and cause damage in plants. On the other hand, studies have shown that salicylic acid (SA) induced resistance to environmental stresses in plants. In this research, the effects of ethylene on chlorophyll (Chl), carotenoid (Car), anthocyanin, flavonoids, ascorbic acid, dehydroascorbic acid, total ascorbate, lipid peroxidation, and ethylene production in leaves of canola pretreated with SA were studied. The plants were grown in pots until they have four leaves. Leaves were sprayed for two days with three different concentrations of SA (0, 0.5, and 1 mM). The plants were treated for three days with three concentrations of ethylene (0, 50, and 100 ppm). At the end of the ethylene treatments, all examined parameters were measured. The results showed that the ethylene treatments induced lipid peroxidation, while SA mitigated this effect. The ethylene treatment lowered significantly Chl and Car contents and anthocyanin accumulation, but SA alleviated these effects. SA induced an increase in ascorbic acid content in canola plants after the ethylene treatments. Therefore, we concluded that SA played an important role in the alleviation of damages caused by stress conditions. and M. M. Tirani, F. Nasibi, Kh. M. Kalantari.