Avocado roots treated with salicylic acid produce phenol-2,4-bis (1,1-dimethylethyl), a compound with antifungal activity

We demonstrated the ability of salicylic acid (SA) to induce a compound in avocado roots that strengthens their defense against Phytophthora cinnamomi. The SA content of avocado roots, before and after the application of exogenous SA, was determined by High-Performance Liquid Chromatography (HPLC). After 4 h of SA feeding, the endogenous level in the roots increased to 223 μg g⁻¹ FW, which was 15 times the amount found in control roots. The methanolic extract obtained from SA-treated avocado roots inhibited the radial growth of P. cinnamomi. A thin layer chromatographic bioassay with the methanolic extract and spores of Aspergillus showed a distinct inhibition zone. The compound responsible for the inhibition was identified as phenol-2,4-bis (1,1-dimethylethyl) by gas chromatography and mass spectrometry. At a concentration of 100 μg/mL, the substance reduced germinative tube length in Aspergillus and radial growth of P. cinnamomi. A commercial preparation of phenol-2,4-bis (1,1-dimethylethyl) caused the same effects on mycelium morphology and radial growth as our isolate, confirming the presence of this compound in the root extracts. This is the first report of the induction of this compound in plants by SA, and the results suggest that it plays an important role in the defense response of avocado.     

Enhanced accumulation of flavonolignans in Silybum marianum cultured roots by methyl jasmonate

Root cultures of Silybum marianum (L.) Gaertn. (Asteraceae) were established from in vitro germinated sterile plantlets. The cultures grew in hormone-free Murashige and Skoog medium. The flavonolignan content in the cultured roots was determined by HPLC using 30% acetonitrile in acidified water (0.5% phosphoric acid). The major flavonolignans produced by the cultured roots were silychristin (74.2 μg g^?1 fresh weight (FW)) and silydianin (8.1 μg g^?1 FW). The flavonolignan precursor taxifolin was also detected in the cultured roots (40.8 μg g^?1 FW). Addition of methyl jasmonate to 7-days-old root cultures for 48 h increased the content of the produced flavonolignans and taxifolin to approximately 300% of the control cultures. Methyl jasmonate also enhanced about sixfold the accumulation of a compound identified as 3,3′,5,5′,7-pentahydroxyflavanone.     

The interactive effect of water deficit and UV-B radiation on salicylic acid accumulation in barley roots and leaves

The aim of the paper was to determine the effect of water deficit (WD) and UV-B radiation acting individually and in combination on salicylic acid (SA) accumulation as well as on the activity of phenylalanine ammonia-lyase (PAL) and benzoic acid hydroxylase (BA2H) that control its biosynthetic route from phenylalanine. An additional aim was to test whether the interaction of these stresses limits the negative effect of a single stress on tissue hydration and membrane injury. Two-week-old seedlings were subjected to water deficit (WD), UV-B irradiation (UV-B) and three different combinations of WD and UV-B: (I) WD and UV-B applied at the same time, (II) UV-B applied before WD, and (III) WD applied before UV-B. Water deficit was imposed by immersing the root system in aerated nutrient solution with polyethylene glycol (PEG 6000) of water potential – 0.5 MPa. UV-B dosage was 24 kJ m⁻² day⁻¹ (0.84 W m⁻²) at the canopy level. UV-B and WD imposed individually and jointly, caused, in a time-dependent manner, an increase in SA content in both organs. Increased levels of SA in WD stressed plants were accompanied by an increase in the activity of PAL and BA2H. However, in plants exposed to UV-B were accompanied only by an increase in the activity of BA2H. Under WD conditions, an earlier increase of SA content was observed in roots than in leaves, which may indicate the involvement of SA in the signal transduction between roots and leaves. In plants exposed to sequential action of WD and UV-B, regardless of the order of its imposition, the effect of each single factor on SA accumulation in leaves was strengthened. WD had a greater effect on water loss and membrane injury than UV-B radiation. In plants exposed to WD after pre-treatment with UV-B radiation, a cross-tolerance mechanism was observed. Leaves of these plants did not show increased lipid peroxidation, measured in terms of malondialdehyde content, and a decrease in water content. This protective action was probably caused by the increase of the SA level in leaves of the UV-B treated plants prior to WD imposition.     

Synchronization of Boron application methods and rates is environmentally friendly approach to improve quality attributes of Mangifera indica L. On sustainable basis

Micronutrient deficiency in the soil is one of the major causes of mango fruit and yield's poor quality. Besides, the consumption of such a diet also causes a deficiency of micronutrients in humans. Boron deficiency adversely affects the flowering and pollen tube formation, thus decreasing mango yield and quality attributes. Soil and foliar application of B are considered a productive method to alleviate boron deficiency. A field experiment was conducted to explore the Boron most suitable method and application rate in mango under the current climatic scenario. There were nine treatments applied in three replications. The results showed that application of T8 = RD + Borax (75 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) and T9 = RD + Borax (150 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) significantly enhanced the nitrogen, potassium, proteins, ash, fats, fiber, and total soluble solids in mango as compared to the control. A significant decrease in sodium, total phenolics contents, antioxidant activity, and acidity as citric acid also validated the effective functioning of T8 = RD + Borax (75 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) and T9 = RD + Borax (150 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) as compared to control. In conclusion, T8 = RD + Borax (75 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) and T9 = RD + Borax (150 g plant ^-1 as a basal application) + H₃ BO₃ (0.8% as a foliar spray) is a potent strategy to improve the quality attributes of mango under the changing climatic situation.     

Simultaneous determination of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam in human serum using gas chromatography–mass spectrometry

A method for the quantitation of midazolam and its metabolites 1-hydroxymidazolam and 4-hydroxymidazolam from human serum capable of monitoring concentrations achieved under therapeutic conditions is presented. The substances were extracted under basic conditions with toluene and the hydroxy metabolites transformed to their tert-butyldimethylsilyl derivatives with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide. The samples were measured by gas chromatography–mass spectrometry. The limits of detection are 0.2 ng ml⁻¹ for midazolam and 0.1 ng ml⁻¹ for 1-hydroxy- and 4-hydroxymidazolam. The coefficients of variation are 3.9% at 5 ng ml⁻¹ for midazolam, 6.7% at 2 ng ml⁻¹ for 1-hydroxymidazolam and 8.8% (22.2%) at 0.5 (0.2) ng ml⁻¹ for 4-hydroxymidazolam.     

Determination of selenium and its compounds in marine organisms

In this study, we investigate the type and quantity of selenium compounds in fish and marine organisms, using ion-pair reversed phase LC–ICP-MS, developed and applied for the analysis of Atlantic cod, Atlantic salmon, Greenland halibut, Atlantic herring, blue mussel, common crab, scallop, calanus, and Euphasia super. Of the samples examined, the lowest level of selenium was found in farmed Atlantic salmon (0.17 mg Se kg⁻¹ dm). The total selenium extraction efficiency by phosphate buffer was 2.5 times higher in sea plankton and shellfish samples than in fish samples. Analysis of Se species in each hydrolysate obtained by proteolysis showed the presence of selenomethionine, which constituted 41.5% of the selenium compounds detected in hydrolysates of Atlantic herring and 98.4% of those in extracts of Atlantic salmon. Inorganic compounds, such as selenates and selenites, were detected mainly in sea plankton and shellfish samples (<0.13 mg Se kg⁻¹ wm), although no correlation was found between the presence of inorganic compounds and total selenium concentration. The accuracy of the total selenium determination was validated using a certified reference material (oyster tissue (NIST 1566b)). A lyophilised powder of cod (Gadus morhua) was used to validate speciation analysis, enzymatic hydrolysis of lyophilised powder of cod recovered 54 ± 6% of total selenium, and SeMet constituted 83.5 ± 5.28% of selenium detected in hydrolysates. The chromatographic detection limits were, respectively, 0.30 ng mL⁻¹, 0.43 ng mL⁻¹, 0.54 ng mL⁻¹, 0.55 ng mL⁻¹, 0.57 ng mL⁻¹ and 0.72 ng mL⁻¹ for selenate, selenomethionine, selenite, Se-methyl-selenocysteine, selenocystine and selenomethionine selenoxide.The data on selenium concentrations and speciation presented here could be useful in estimating levels of selenium intake by seafood consumption.     

Management of white mold in processing tomatoes by Trichoderma spp. and chemical fungicides applied by drip irrigation

Field trials were carried out to evaluate six treatments combining biological agents and chemical fungicides applied via chemigation against white mold (Sclerotinia sclerotiorum) on processing tomatoes. The experiment was performed in Goiânia, Brazil, with tomato hybrid Heinz 7155 in 2009 and 2010 in a field previously infested with S. sclerotiorum sclerotia. Treatments were arranged in a randomized complete block design in a 2 × 3 factorial structure (with and without Trichoderma spp. 1.0 × 10⁹ viable conidia mL⁻¹ ha⁻¹) × fluazinam (1.0 L ha⁻¹), procimidone (1.5 L ha⁻¹) and control, applied by drip irrigation. Treatments were applied three times 10 days apart, starting one month after transplanting. Each treatment consisted of plots with three 72-meter rows with four plants m⁻¹ and 1.5 m spacing between rows, with three replications. Based on disease incidence evaluated weekly, the area under the disease progress curve (AUDPC) was obtained. Yield and its components were evaluated in addition to fruit pH and °Brix. Results were subjected to ANOVA, Scott-Knott (5%), and regression analysis. Biocontrol using Trichoderma spp. via chemigation singly or in combination with synthetic fungicides fluazinam and procimidone reduced AUDPC and increased fruit yield up to 25 t ha⁻¹. The best treatment for controlling white mold also increased pulp yield around 1.0 and 7.0 t ha⁻¹ in 2009 and 2010, respectively. The present work demonstrated the advantages of white mold biological control in processing tomato crops, where drip irrigation favored Trichoderma spp. delivery close to the plants and to the inoculum source.     

Phenolic compounds composition and physiological attributes of Matricaria chamomilla grown in copper excess

Four-week old plants of chamomile (Matricaria chamomilla) cultivated in nutrient solution were exposed to copper (3, 60 and 120 μM) for 10 days. At 120 μM, Cu decreased dry mass production, water, chlorophyll and nitrogen content in both the leaf rosettes and roots. Five phenolic acids were detected in methanol extracts of the leaf rosettes (protocatechuic, p-hydroxybenzoic, vanillic, chlorogenic and salicylic acid) and six additional compounds (gentisic, syringic, caffeic, sinapic and o-/p-coumaric acid) were released after acid hydrolysis. Most of the 11 phenolic acids detected increased in 60 μM Cu but in the 120 μM treatment their contents were lower or not significantly different from the control. Among coumarin-related compounds, (Z)- and (E)-2-ß-d-glucopyranosyloxy-4-methoxycinnamic acids increased in 60 and 120 μM Cu while herniarin rose in the 3 and 60 μM Cu by the end of the experiment. The amounts of umbelliferone were not affected by any of the doses tested. These facts in relation to antioxidative properties of phenolic metabolites are also discussed. The malondialdehyde content of the leaf rosettes was not affected by exposure of plants to 120 μM Cu in a time-course experiment but in the roots a sharp increase was observed after 24 and 48 h of treatment. At 120 μM, Cu stimulated a 9-fold higher K⁺ loss than the 60 μM treatment while at the lowest concentration it stimulated potassium uptake. Cu accumulation in the roots was 3-, 49- and 71-fold higher than that in the leaf rosettes in the 3, 60, and 120 μM Cu treatments, respectively. Results suggest that 120 μM Cu dose is limiting for chamomile growth under the conditions of present research.     

Salicylic Acid Enhances Resistance to Fusarium oxysporum f. sp. phaseoli in Common Beans (Phaseolus vulgaris L.)

Fusarium wilt caused by Fusarium oxysporum f. sp. phaseoli (Fop) is one of the most serious diseases of common bean (Phaseolus vulgaris L.) and is especially prevalent in China. In this study, we demonstrated that exogenous application of 2 mM salicylic acid (SA) by leaf spraying could induce resistance against Fop in common beans. Accumulation of free and conjugated SA in roots was detected by HPLC analysis and compared. After 168 h of daily SA treatment, the free SA level in roots was eight times higher than in control plants. However, the conjugated SA level reached a peak at 72 h of SA treatment, which was nine times higher than in control plants, and then sharply declined at 168 h. The activities of phenylalanine ammonia lyase (PAL, EC 4.3.1.5) and peroxidases (POX, EC 1.11.1.7) in roots were 9.4 and 6.3 times higher than in control plants after 168 h of SA treatment, respectively. H₂O₂ and O₂ ^? levels reached 2.6 and 13.6 times higher, respectively, than in the control plants at 168 h after SA treatment. Host reactions of SA-treated plant roots infected by Fop observed in microscopy included the deposition of electron-dense materials along the secondary walls. However, untreated inoculated plants showed marked cell wall degradation and total cytoplasm disorganization of root cells. These results indicated that SA applied to foliar tissue is capable of enhancing the systemic acquired resistance of common bean roots to infection by Fop.     

Microencapsulation of Bacillus subtilis B99-2 and its biocontrol efficiency against Rhizoctonia solani in tomato

Biological control is a promising approach to protecting plants from disease. Bacillus subtilis has been widely used in agriculture for promoting plant growth and biocontrol. However, their short shelf life limits the application of biological pesticides. The objectives of this study were to develop a microencapsulation procedure of B. subtilis B99-2 using maltodextrin and gum arabic as wall materials to determine the optimum conditions of spray-drying in microencapsulation, evaluate storage stability of microcapsules, and assess their biocontrol efficiency against Rhizoctonia solani in tomato under field conditions. We microencapsulated the Bacillus thallus by spray-drying with various concentrations of the wall material. Maltodextrin was found to be an efficient wall material, especially at concentrations higher than 80%, while gum arabic did not affect the bacterial survival rate. The mean survival rate of B. subtilis was more than 90%, when spray drying was performed at 145 °C, with a feed flow rate of 550 mL h⁻¹, and a spray pressure of 0.15 MPa. B. subtilis microcapsule survival rate was 87.53% after 540 d of storage, which was a longer shelf life than that of wettable powders. Moreover, its biocontrol efficacy reached 79.91% when a dosage of 300 g hm⁻² was used, the microcapsule showed higher control efficacy than Thiram wettable powder against R. solani in tomato under field conditions. All these characteristics indicated that B. subtilis microcapsules have the potential to become a successful biocontrol product.     

Overexpression of polyphosphate kinase gene (ppk) increases bioinsecticide production by Bacillus thuringiensis

Polyphosphate (polyP), synthesized by polyP kinase (PPK) using the terminal phosphate of ATP as substrate, performs important functions in every living cell. The present work reports on the relationship between polyP metabolism and bioinsecticide production in Bacillus thuringiensis subsp. israelensis (Bti). The ppk gene of Bti was cloned into vector pHT315 and the effect of its overexpression on endotoxin production was determined. Endotoxin production by the recombinant strain was found to be consistently higher than that by the wild type strain and the strain that carried the empty plasmid. The toxicity of the recombinant mutant strain (LC₅₀ 5.8 ± 0.6 ng ml^?1) against late 2nd instar Culex quinquefasciatus was about 7.7 times higher than that of Bti (LC₅₀ 44.9 ± 7 ng ml^?1). To our knowledge this is the first reported study which relates polyP metabolism with bioinsecticide biosynthesis.     

Analysis of aminoglycoside residues in bovine milk by liquid chromatography electrospray ion trap mass spectrometry after derivatization with phenyl isocyanate

A derivatization procedure using phenyl isocyanate was adapted to liquid chromatography ion trap mass spectrometry (LC–MSⁿ) for confirmation and quantification of aminoglycoside residues in milk. Aminoglycoside residues were extracted from milk with acid and isolated from the matrix with a weak cation exchange solid-phase extraction cartridge. After isolating the compounds from the milk, derivatives of gentamicin, neomycin, and tobramycin were formed by reacting the drugs with phenyl isocyanate in the presence of triethylamine. The analytes were separated using a dilute formic acid/acetonitrile gradient on a reversed-phase LC column. The derivatized compounds were analyzed using positive ion electrospray LC–MSⁿ with ion trap detection. Product ion spectra were generated from the derivatized protonated molecules. Specific ion transitions were evaluated for quantitative determination and qualitative confirmation of residues in milk. Using this procedure, residues were qualitatively confirmed in milk samples fortified with gentamicin and neomycin at levels ranging from 15 to 300 ng mL^?1. Gentamicin has four major components that were successfully separated and confirmed independently; for quantitative determination the peak areas from the four analogs were summed. Tobramycin was added as an internal standard for quantitation to mitigate the effects of matrix ion suppression and variable recoveries. Overall recoveries for this method ranged from 80% to 120% with relative standard deviations of less than 25%. The method detection limits are 9.8 ng mL^?1 for NEO and 12.8 ng mL^?1 for total GEN residues.     

Gibberellic acid mediated induction of salt tolerance in wheat plants: Growth,ionic partitioning,photosynthesis, yield and hormonal homeostasis

In order to elucidate the GA₃-priming-induced physiochemical changes responsible for induction of salt tolerance in wheat, the primed and non-primed seeds of two spring wheat (Triticum aestivum L.) cultivars, namely, MH-97 (salt intolerant) and Inqlab-91 (salt tolerant) were sown in a field treated with 15 dS m⁻¹ NaCl salinity. Although all the three concentrations (100, 150 and 200 mg L⁻¹) of GA₃ were effective in improving grain yield in both cultivars, the effect of 150 mg L⁻¹ GA₃ was much pronounced particularly in the salt intolerant cultivar when under salt stress. Seed priming with GA₃ altered the pattern of accumulation of different ions between shoots and roots in the adult plants of wheat under saline conditions. Treatment with GA₃ (150 mg L⁻¹) decreased Na⁺ concentrations both in the shoots and roots and increased Ca²⁺ and K⁺ concentrations in the roots of both wheat cultivars. GA₃-priming did not show consistent effect on gaseous exchange characteristics and the concentrations of auxins in the salt stressed plants of both wheat cultivars. However, all concentrations of GA₃ reduced leaf free ABA levels in the salt intolerant, while reverse was true in the salt tolerant cultivar under saline conditions. Priming with GA₃ (150 mg L⁻¹) was very effective in enhancing salicylic acid (SA) concentration in both wheat cultivars when under salt stress. Treatment with GA₃ (100–150 mg L⁻¹) lowered leaf free putrescine (Put) and spermidine (Spd) concentrations in the plants of both wheat cultivars. The decrease in polyamines (Put and Spd) and ABA concentrations in the salt stressed plants of the salt intolerant cultivar treated with GA₃ suggested that these plants might have faced less stress compared with control. Thus, physiologically, GA₃-priming-induced increase in grain yield was attributed to the GA₃-priming-induced modulation of ions uptake and partitioning (within shoots and roots) and hormones homeostasis under saline conditions.     

An o-aminobenzoic acid film-based immunoelectrode for detection of the cardiac troponin T in human serum

An amperometric immunosensor for cardiac troponin T detection in human serum troponin T, a marker considered as “gold standard” for acute myocardial infarction diagnosis, is described. A stable carboxylic film to covalently bind antibodies against cTnT onto electrode surface was achieved with electropolymerization of the o-aminobenzoic acid. A fractional factorial study was performed to optimize the electropolymerization parameters. Cyclic voltammetry assays were carried out for characterize steps of the modified electrode surface. The obtained calibration curve at −0.05 V by amperometry presented a good linear response range from 0.05 to 5.0 ng mL⁻¹ cTnT with a correlation coefficient of 0.992 (n = 6) and 0.016 ng mL⁻¹ detection limit. The electrodes showed a good stability upon the analytical responses retaining 91.6% of its initial response after 18 days. This sensor showed outgoing results regarding sensitivity allowing reliable measurements of the cTnT at levels of clinical significance for acute myocardial infarctions diagnosis.     

Physiological control of leaf methane emission from wetland plants

The transport of methane from the rhizosphere to the atmosphere takes place in the intercellular spaces and stomata of wetland plants, and foliar gas exchange is one of the critical steps of the transport process. The objectives of our research were to investigate: (i) variation in foliar gas exchange among four common wetland plant species (i.e., Peltandra virginica L., Orontium aquaticum L., Juncus effusus L., and Taxodium distichum L.), (ii) the role of key environmental factors (i.e., light, temperature, and carbon dioxide concentration) in controlling foliar methane emission, and (iii) physiological mechanisms underlying the variation in methane emission due to species and the environment. Experiments were conducted in an instantaneous, flow-through gas-exchange system that operated on a mass balance approach and concurrently measured foliar fluxes of methane, water vapor, and carbon dioxide. The chamber system allowed for the control of light, temperature, humidity, and carbon dioxide concentration. Diel patterns of methane emission varied among species, with daylight emissions from P. virginica and O. aquaticum 2–4 times those of J. effusus and T. distichum in saturating light. Foliar methane emission from P. virginica (1.80 μmol m⁻² s⁻¹) under ambient daylight conditions was an order of magnitude higher than that of the other three species (∼0.20 μmol m⁻² s⁻¹). As leaf temperature was increased by 10 °C, methane emission increased by a factor of 1.5–2.2, and the temperature effect was independent of stomatal conductance. When data were pooled among the four species, varying the light and carbon dioxide concentrations in a stepwise manner produced changes in foliar methane emission that were associated with stomatal conductance (r² = 0.52). To scale our observations to other wetland plant species, a stepwise multiple regression model is offered that incorporates stomatal conductance and net carbon dioxide assimilation to estimate instantaneous methane emission from foliar surfaces. The model indicates that changes in stomatal conductance affect methane emission three times more than equivalent changes in net carbon dioxide assimilation.     

Cadmium toxicity in tomato (Lycopersicon esculentum) plants grown in hydroponics

The effects of Cd have been investigated in tomato (Lycopersicon esculentum) plants grown in a controlled environment in hydroponics, using Cd concentrations of 10 and 100 μM. Cadmium treatment led to major effects in shoots and roots of tomato. Plant growth was reduced in both Cd treatments, leaves showed chlorosis symptoms when grown at 10 μM Cd and necrotic spots when grown at 100 μM Cd, and root browning was observed in both treatments. An increase in the activity of phosphoenolpyruvate carboxylase, involved in anaplerotic fixation of CO₂ into organic acids, was measured in root extracts of Cd-exposed plants. Also, significant increases in the activities of several enzymes from the Krebs cycle were measured in root extracts of tomato plants grown with Cd. In leaf extracts, significant increases in citrate synthase, isocitrate dehydrogenase and malate dehydrogenase activities were also found at 100 μM Cd, whereas fumarase activity decreased. These data suggest that at low Cd supply (10 μM) tomato plants accumulate Cd in roots and this mechanism may be associated to an increased activity in the PEPC–MDH–CS metabolic pathway involved in citric acid synthesis in roots. Also, at low Cd supply some symptoms associated with a moderate Fe deficiency could be observed, whereas at high Cd supply (100 μM) effects on growth overrule any nutrient interaction caused by excess Cd. Cadmium excess also caused alterations on photosynthetic rates, photosynthetic pigment concentrations and chlorophyll fluorescence, as well as in nutrient homeostasis.     

The measurement of ecstasy in human hair by triple phase directly suspended droplet microextraction prior to HPLC-DAD analysis

New pre-concentration technique, triple phase suspended droplet microextraction (SD-LPME) and liquid chromatography-photodiode array detection was applied to determine ecstasy, MDMA (3,4-methylendioxy-N-methylamphetamine) in hair samples. In this research MDMA in hair was digested and after treatment extracted. The effective parameters were investigated and method was evaluated. Under the optimal conditions, the MDMA was enriched by factor 98.11. Linearity (r = 0.9921), was obtained in the range of 10–15,000 ng mL^?1 and detection limit was 0.1 ng mL^?1.     

Responses of non-protein thiols to Cd exposure in Cd hyperaccumulator Arabis paniculata Franch

We investigated the responses of phytochelatins (PCs), glutathione (GSH) and other non-protein thiols in Cd hyperaccumulator Arabis paniculata after Cd exposure. Applying γ-glutamylcysteine synthetase (γ-ECS) inhibitor, l-buthionine-sulfoximine (BSO), the roles of PCs in Cd tolerance and Cd accumulation in A. paniculata were evaluated. Plants were exposed to four Cd concentrations (0, 50, 100 and 250 μM) for different times (2w or 3w) with and without BSO. Overall, Cd exposure had little impact on plant biomass after 2w or 3w of growth except at the highest Cd level. A. paniculata tolerated ≤100 μM Cd with up to 1127 mg kg^?1 Cd in the shoots and 5624 mg kg^?1 Cd in the roots after 3w of Cd exposure. Cd exposure induced formation of PCs and three unknown thiols in the roots, but none were detected in the shoots. BSO had no significant effect on Cd sensitivity in plants though it reduced Cd accumulation in the roots. In addition, the molar ratio of PCs:Cd, which ranged from 0.7 to 1.3 after exposing to 50–100 μM Cd without BSO in the roots, was close to the value expected for PC-mediated Cd sequestration in plants. Those data indicate that GSH and PCs did not contribute to Cd tolerance in the shoots and Cd transport from the root to shoot in A. paniculata, but they may play an important role in Cd accumulation and Cd complexation in the roots of A. paniculata.     

Mixotrophy in the newly described dinoflagellate Yihiella yeosuensis: A small,fast dinoflagellate predator that grows mixotrophically,but not autotrophically

To investigate tropical roles of the newly described Yihiella yeosuensis (ca. 8 μm in cell size), one of the smallest phototrophic dinoflagellates in marine ecosystems, its trophic mode and the types of prey species that Y. yeosuensis can feed upon were explored. Growth and ingestion rates of Y. yeosuensis on its optimal prey, Pyramimonas sp. (Prasinophyceae), as a function of prey concentration were measured. Additionally, growth and ingestion rates of Y. yeosuensis on the other edible prey, Teleaulax sp. (Cryptophyceae), were also determined for a single prey concentration at which both these rates of Y. yeosuensis on Pyramimonas sp. were saturated. Among bacteria and diverse algal prey tested, Y. yeosuensis fed only on small Pyramimonas sp. and Teleaulax sp. (both cell sizes = 5.6 μm). With increasing mean prey concentrations, both specific growth and ingestion rates of Y. yeosuensis increased rapidly before saturating at a mean Pyramimonas concentration of 109 ng C mL⁻¹ (2725 cells mL⁻¹). The maximum growth rate (mixotrophic growth) of Y. yeosuensis fed with Pyramimonas sp. at 20 °C under a 14:10-h light-dark cycle of 20 μE m⁻² s⁻¹ was 1.32 d⁻¹, whereas the growth rate of Y. yeosuensis without added prey was 0.026 d⁻¹. The maximum ingestion rate of Y. yeosuensis fed with Pyramimonas sp. was 0.37 ng C predator⁻¹ d⁻¹ (9.3 cells predator⁻¹ d⁻¹). At a Teleaulax concentration of 1130 ng C mL⁻¹ (66,240 cells mL⁻¹), growth and ingestion rates of Y. yeosuensis fed with Teleaulax sp. were 1.285 d⁻¹ and 0.38 ng C predator⁻¹ d⁻¹ (22.4 cells predator⁻¹ d⁻¹), respectively. Thus, Y. yeosuensis rarely grows without mixotrophy, and mixotrophy supports high growth rates in Y. yeosuensis. Y. yeosuensis has the highest maximum mixotrophic growth rate with the exception of Ansanella graniferaamong engulfment feeding mixotrophic dinoflagellates. However, the high swimming speed of Y. yeosuensis (1572 μm s⁻¹), almost the highest among phototrophic dinoflagellates, may prevent autotrophic growth. This evidence suggests that Y. yeosuensis may be an effective mixotrophic dinoflagellate predator on Pyramimonas and Teleaulax, and occurs abundantly during or after blooms of these two prey species.     

Responses of grafted tomato (Solanum lycopersiocon L.) to abiotic stresses in Saudi Arabia

Quantity and quality of irrigation water are considered the most imperative limiting factors for plant production in arid environment. Adoptions of strategies can minimize crop water consumption while nonexistent yield reduction is considered challenge for scholars especially in arid environment. Grafting is regarded as a promising tool to avoid or reduce yield loss caused by abiotic stresses. Tomato (Solanum lycopersium Mill.), commercial cultivar Faridah was grafted on Unifort rootstock and grown under regulated deficit irrigation (RDI) (100%, 80% and 60% ETc), using two types of irrigation water, fresh (EC = 0.86 dS/m) and brackish (EC = 3.52 dS/m). The effects of grafting and RDI on water use efficiency, vegetative growth, yield, fruit quality were investigated. Plant vegetative growth was reduced under water and salinity stresses. Grafting the plant significantly improves the vegetative growth under both conditions. The results showed that crop yield, Ca⁺² and K⁺ were considerably increased in grafted tomato compared to non-grafted plants under water and salinity stresses. Grafted tomato plants accumulated less Na⁺ and Cl⁻, especially under high levels of salinity compared to non-grafted plants. Grafting tomato plants showed a slight decrease on the fruit quality traits such as vitamin C, titratable acidity (TA) and total soluble solids (TSS). This study confirmed that grafted tomato plants can mitigate undesirable impact of salt stress on growth and fruit quality.