Photosynthetic parameters change in Lycopersicon esculentum leaves under nutrient deficiencies

Lycopersicon esculentum leaves cultivated hydroponically for 24 and 48 hrs with various specific mineral deficits had their photosynthetic characteristics examined. After 24 hrs of K+, NO3-, and PO42- deficiency, a substantial induction of net photosynthetic rate was observed. The net photosynthetic rate of SO42-, Mg2+, Fe2+, NO3-, Ca2+ and PO42- deficits was significantly induced by the 48 hr exposure. After 24 hrs of deficiencies in SO42-, Mg2+, Fe2+, NO3-, Ca2+ and PO42-, stomata conductance was dramatically increased. Deficiencies in SO42-, Fe2+, NO3-, Ca2+ and PO42- were continuously induced over 48 hrs. After 24 hrs of SO42-, Fe2+, NO3-, Ca2+ and PO42- deficiencies, intercellular CO2 concentration shows a considerable induction. After 48 hrs of K+, SO42-, Mg2+ and NO3-deficits, this behavior remained strongly induced. Water use efficiency considerably decreased in response to these changes after 24 hrs of SO42-, Fe2+, NO3- and PO42- deficiencies and this effect continued after 48 hrs of Mg2+, NO3-, Ca2+ and PO42- deficiencies. Deficits in K+, SO42-, Mg2+, Fe2+, NO3-, Ca2+ and PO42- for 24 hrs dramatically increased transpiration rate, which was modified by those deficiencies. A 48 hr exposure to NO3-, Ca2+ and PO42- deficiency dramatically increased the transpiration rate. After 48 hrs, an SO42- deficit drastically decreased the transpiration rate. The findings indicate that after a short term of exposure, it may be possible to diagnose a specific mineral shortage and determine which mineral influenced the parameters of photosynthesis in such a way that the selected parameters responded in a manner that was consistent with the duration of exposure

Assessment of exogenous application of plant growth regulators on Cress seed germination and ?-Galactosidase activity

Plant growth regulators (PGRs) were involved in several types of abiotic stress responses by means of improving seed germination and modifying the growth and development of medicinally important Lepidium sativum via alleviating the negative effects of abiotic stresses. Therefore, the present research was carried out to investigate the effects of exogenous application of PGRson seed germination, protein content and ?-galactosidase activity of L. sativum. Germination of L. sativum seeds was monitored for a short interval after the start of incubation until growth became 100%. While cytokinin treatment showed a positive effect on seed germination more than Gibberellic acid (GA), salicylic acid (SA) produced a higher negative effect than auxins. Quantifying changes in total protein content during seed germination as influenced by PGRs revealed that all PGRs have to exert a positive effect arranged in the following order: SA ? auxin ? cytokinin ? GA. Parallel to changes in germination percentage and total protein content of seed, a negative effect was attainedon ?-galactosidase specific activity in response to PGRs with the following arrangement: SA ? auxin ? cytokinin ? GA.In conclusion, the present study proposed the potential importance of the type and magnitude of exogenously applied PGRs during the germination of easily or even more difficult-to-germinate seeds

Antibacterial synergy of Tritirachium oryzae-produced silver nanoparticles with different antibiotics and essential oils derived from Cupressus sempervirens and Asteriscus graveolens (Forssk)

Purpose: To carry out eco-friendly biosynthesis of fungi-derived silver nanoparticles (AgNPs) and investigate their antibacterial synergies with essential oils (EOs) of Asteriscus graveolens (Forssk.) Less. and Cupressus sempervirens. Methods: Biosynthesis of AgNPs was carried out using a cell-free filtrate of Tritirachium oryzae. The biosynthesized AgNPs characteristics were assessed using different methods, including ultravioletvisible spectrophotometry (UV), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results: Obvious synergistic effects were observed between AgNPs and chloramphenicol, vancomycin, nitrofurantoin or tetracycline with Pseudomonas aeruginosa, through increases in fold area of inhibition (IFAs) within the range of 2.4 to 9.0. Synergistic interactions were also seen between AgNPs and the antibiotics used, depending on the strain. Increase in IFA ranged from 1- to 3-fold for S. aureus, E. coli and P. aeruginosa. Similarly, combinations of AgNPs, EO of A. graveolens and cefotaxime, nitrofurantoin or amoxicillin against P. aeruginosa led to 10-, 3- and 10-fold synergy, respectively. In contrast, the use of AgNPs and trimethoprim, tetracycline or amoxicillin against E. coli led to 1 to 6-fold synergy. The best synergistic capacity resulted from AgNPs and the EO of C. sempervirens and trimethoprim against S. epidermidis, which yielded 29-fold increase in IFA. The use of combination of AgNPs and vancomycin against P. aeruginosa led to 16.4-fold enhancement of IFA. Conclusion: The findings can potentially lead to the development of a new perception of antibacterial agents (innovative medications) involving the incorporation of nanoparticles (NPs) or new materials that potentially synergize with antibiotics, NPs and the EOs of different plants

Efficient acclimation of the chloroplast antioxidant defence of Arabidopsis thaliana leaves in response to a 10- or 100-fold light increment and the possible involvement of retrograde signals

Chloroplasts are equipped with a nuclear-encoded antioxidant defence system the components of which are usually expressed at high transcript and activity levels. To significantly challenge the chloroplast antioxidant system, Arabidopsis thaliana plants, acclimated to extremely low light slightly above the light compensation point or to normal growth chamber light, were moved to high light corresponding to a 100- and 10-fold light jump, for 6 h and 24 h in order to observe the responses of the water–water cycle at the transcript, protein, enzyme activity, and metabolite levels. The plants coped efficiently with the high light regime and the photoinhibition was fully reversible. Reactive oxygen species (ROS), glutathione and ascorbate levels as well as redox states, respectively, revealed no particular oxidative stress in low-light-acclimated plants transferred to 100-fold excess light. Strong regulation of the water–water cycle enzymes at the transcript level was only partly reflected at the protein and activity levels. In general, low light plants had higher stromal (sAPX) and thylakoid ascorbate peroxidase (tAPX), dehydroascorbate reductase (DHAR), and CuZn superoxide dismutase (CuZnSOD) protein contents than normal light-grown plants. Mutants defective in components relevant for retrograde signalling, namely stn7, ex1, tpt1, and a mutant expressing E .coli catalase in the chloroplast showed unaltered transcriptional responses of water–water cycle enzymes. These findings, together with the response of marker transcripts, indicate that abscisic acid is not involved and that the plastoquinone redox state and reactive oxygen species do not play a major role in regulating the transcriptional response at t=6 h, while other marker transcripts suggest a major role for reductive power, metabolites, and lipids as signals for the response of the water–water cycle

Acclimation of normal or low light grown Arabidopsis thaliana to high light

Alsharafa K. Acclimation of normal or low light grown Arabidopsis thaliana to high light. Bielefeld; 2012

Fast Retrograde Signaling in Response to High Light Involves Metabolite Export, MITOGEN-ACTIVATED PROTEIN KINASE6, and AP2/ERF Transcription Factors in Arabidopsis

Vogel MO, Moore M, König K, et al. Fast Retrograde Signaling in Response to High Light Involves Metabolite Export, MITOGEN-ACTIVATED PROTEIN KINASE6, and AP2/ERF Transcription Factors in Arabidopsis. The Plant Cell. 2014;26(3):1151-1165.Regulation of the expression of nuclear genes encoding chloroplast proteins allows for metabolic adjustment in response to changing environmental conditions. This regulation is linked to retrograde signals that transmit information on the metabolic state of the chloroplast to the nucleus. Transcripts of several APETALA2/ETHYLENE RESPONSE FACTOR transcription factors (AP2/ERF-TFs) were found to respond within 10 min after transfer of low-light-acclimated Arabidopsis thaliana plants to high light. Initiation of this transcriptional response was completed within 1 min after transfer to high light. The fast responses of four AP2/ERF genes, ERF6, RRTF1, ERF104, and ERF105, were entirely deregulated in triose phosphate/phosphate translocator (tpt) mutants. Similarly, activation of MITOGEN-ACTIVATED PROTEIN KINASE6 (MPK6) was upregulated after 1 min in the wild type but not in the tpt mutant. Based on this, together with altered transcript regulation in mpk6 and erf6 mutants, a retrograde signal transmission model is proposed starting with metabolite export through the triose phosphate/phosphate translocator with subsequent MPK6 activation leading to initiation of AP2/ERF-TF gene expression and other downstream gene targets. The results show that operational retrograde signaling in response to high light involves a metabolite-linked pathway in addition to previously described redox and hormonal pathways

Efficacy of <i>Sterculia diversifolia</i> Leaf Extracts: Volatile Compounds, Antioxidant and Anti-Inflammatory Activity, and Green Synthesis of Potential Antibacterial Silver Nanoparticles

Sterculia diversifolia, widely distributed in Jordan as an ornamental plant, is a synonoum for Brachychiton populneus. Phytochemical studies examining the volatile chemicals in Sterculia diversifolia leaves are limited, despite the rising demand for their numerous applications. Furthermore, it was only recently that a report described the friendly synthesis of silver nanoparticles (AgNPs) using aqueous extract derived from Brachychiton populneus leaves. Therefore, AgNPs were produced using either aqueous plant extracts (AgWPE) or ethanolic plant extracts (AgEPE), and Shimadzu GC-MS equipment was used to detect volatile compounds in the ethanolic leaf extracts. GC-MS profile of leaf ethanolic extracts of the Jordanian chemotypes of S. diversifolia revealed the existence of major components: (3β)-Lup-20(29)-en-3-ol acetate (30.97%) and 1-octadecyne (24.88). Other compounds are squalene (7.19%), germanicol (6.23), dl-α-tocopherol (5.24), heptacosane (4.41), phytol (3.54) and pentacosane (2.89). According to published studies, these reported chemicals have numerous uses, including as animal feed, vitamin precursors, possible eco-friendly herbicides, antioxidants, and anti-inflammatory agents. Aqueous extracts of S. diversifolia leaves had total phenolic of 5.33 mg GAE/g extract and flavonoid contents of 64.88 mg QE/g extract, respectively. The results indicated the contribution of phenolic and flavonoids to this plant’s anti-inflammatory and antioxidant properties. The reduction in AgNO3 to AgNPs using S. diversifolia leaf extracts was confirmed by the change in solution color from colorless to dark black. Further characterization was attempted by X-ray diffraction, Malvern zeta-sizer and scanning electron microscope. The efficacy of synthesized Ag nanoparticles using aqueous or ethanolic plant extract of S. diversifolia against the Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus showed appreciable activity at 25 µg/mL concentration compared to the source plant extracts

Kinetics of retrograde signalling initiation in the high light response of Arabidopsis thaliana

Alsharafa K, Vogel MO, Oelze M-L, et al. Kinetics of retrograde signalling initiation in the high light response of Arabidopsis thaliana. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 2014;369(1640): 20130424.High light acclimation depends on retrograde control of nuclear gene expression. Retrograde regulation uses multiple signalling pathways and thus exploits signal patterns. To maximally challenge the acclimation system, Arabidopsis thaliana plants were either adapted to 8 (low light (L-light)) or 80 µmol quanta m(-2) s(-1) (normal light (N-light)) and subsequently exposed to a 100- and 10-fold light intensity increase, respectively, to high light (H-light, 800 µmol quanta m(-2) s(-1)), for up to 6 h. Both L → H- and N → H-light plants efficiently regulated CO2 assimilation to a constant level without apparent damage and inhibition. This experimental set-up was scrutinized for time-dependent regulation and efficiency of adjustment. Transcriptome profiles revealed that N-light and L-light plants differentially accumulated 2119 transcripts. After 6 h in H-light, only 205 remained differently regulated between the L → H- and N → H-light plants, indicating efficient regulation allowing the plants to reach a similar transcriptome state. Time-dependent analysis of transcripts as markers for signalling pathways, and of metabolites and hormones as possibly involved transmitters, suggests that oxylipins such as oxophytodienoic acid and jasmonic acid, metabolites and redox cues predominantly control the acclimation response, whereas abscisic acid, salicylic acid and auxins play an insignificant or minor role