Nitrate Reductase Activity Research Articles

Synergistic enhancement of the phytostabilization of a semiarid mine tailing by a combination of organic amendment and native microorganisms (Funneliformis mosseae and Bacillus cereus)

The goal of this work was to evaluate the effects of fermented sugar beet residue and inoculation with a native arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae (Nicol. and Gerd.) Gerd. and Trappe, or a native bacterium, Bacillus cereus Frankland & Frankland, alone or in combination, on the establishment of Lygeum spartum L. seedlings grown in a mine tailing under semiarid conditions. We conducted a field study to analyse root and shoot dry biomass, shoot nutrient contents, mycorrhization, plant nitrate reductase (NR) and acid phosphomonoesterase activities, soil enzyme activities and aggregate stability. Ten months after field transplanting, it was found that the three experimental factors had interacted synergistically with regard to shoot and root biomass, with increases of about 410% and 370%, respectively relative to plants in the untreated soil. The treatment combining all three factors increased the root content of all heavy metals, and the levels of nitrogen (N), phosphorus, potassium and NR activity in shoot tissues, whereas it decreased root acid phosphomonoesterase activity. Soil dehydrogenase, protease and β-glucosidase activities, total N content and aggregate stability were increased by the combined treatment. In conclusion, the combination of the organic amendment, the native AM fungus and the native bacterium can be regarded as a suitable tool for phytostabilization with L. spartum due to its ability to enhance the tolerance of plants to heavy metals, improve the plant nutritional status and increase the soil microbial function related to the C cycling.

Klebsiella oxytoca (EN-B2): A novel type of simultaneous nitrification and denitrification strain for excellent total nitrogen removal during multiple nitrogen pollution wastewater treatment

The poor total nitrogen (TN) removal rate achieved using microorganisms to treat wastewater polluted with multiple types of nitrogen was improved using a novel simultaneous nitrification and denitrification strain (Klebsiella oxytoca EN-B2). Strain EN-B2 rapidly eliminated ammonium, nitrate, and nitrite, giving maximum elimination rates of 4.58, 7.46, and 7.83 mg/(L h), respectively, equivalent to TN elimination rates of 4.35, 6.92, and 7.11 mg/(L h), respectively. The simultaneous nitrification and denitrification system gave ammonium and nitrite elimination rates of 7.14 and 9.17 mg/(L h), respectively, and a TN elimination rate ≥ 9.0 mg/(L h). Nitrogen balance calculations indicated that 51.22 %, 31.62 % and 46.82 % of TN in systems containing only ammonium, nitrite, and nitrate, respectively, were lost as nitrogenous gases. The ammonia monooxygenase, hydroxylamine oxidoreductase, nitrate reductase and nitrite reductase enzyme activities were determined. The results indicated that strain EN-B2 can be used to treat wastewater polluted with multiple types of nitrogen.

Phosphite treatment can improve root biomass and nutrition use efficiency in wheat.

Phosphite represents a reduced form of phosphate that belongs to a class of crop growth-promoting chemicals termed biostimulants. Previous research has shown that phosphite application can enhance root growth, but its underlying mechanism, especially during environmental stresses, remains elusive. To uncover this, we undertook a series of morphological and physiological analyses under nutrient, water and heat stresses following a foliar application in wheat. Non-invasive 3D imaging of root system architecture directly in soil using X-ray Computed Tomography revealed that phosphite treatment improves root architectural traits and increased root biomass. Biochemical and physiological assays identified that phosphite treatment significantly increases Nitrate Reductase (NR) activity, leaf photosynthesis and stomatal conductance, suggesting improved Nitrogen and Carbon assimilation, respectively. These differences were more pronounced under heat or drought treatment (photosynthesis and photosystem II stability) and nutrient deficiency (root traits and NR). Overall our results suggest that phosphite treatment improves the ability of plants to tolerate abiotic stresses through improved Nitrogen and Carbon assimilation, combined with improved root growth which may improve biomass and yield.

Phenotypic and Biochemical Characterization of Rhizobia Associated with Medicagopolymorpha Growing in Rajasthan

In present study, a total of 15rhizobial isolates were isolated from the root nodules of Medicagopolymorphagrowing in Jaipur and were characterized for their phenotypic, biochemical and plant growth promoting activities. The root nodules of M. polymorpha were elongated, branched and indeterminate. All isolated rhizobia were highly diverse in their physiological traits. Based on colony morphology, all isolates were categorized into six groups. Major group containing 6 isolates (MP1, MP3, MP9, MP10, MP11 and MP13) showed white, opaque, raised, smooth edges, non-gummy, and mucilaginous characteristics. Four rhizobia strains MP3, MP4, MP9, and MP15 showed salt-tolerance up to 3% and were well adapted to high alkaline conditions and exhibited growth in extremely alkaline media (pH 10). Majority of strains showed positive result for IAA production, nitrate reductase and catalase activity. In addition, citrate utilization, ammonia production, phosphate solubilization and cellulase activity were observed in few isolates. In present study, some rhizobia isolates like MP3, and MP15 were very versatile rhizobia that showed high plant growth promoting activities (IAA production and phosphate solubilization) and were also tolerant to high pH and salt concentration. Such type of superior rhizobia can be part of biofertilizers to enhance legume crop productivity in an ecofriendly manner without application of chemical fertilizers. Our study suggested that rhizobia isolates associated with Medicagopolymorpha were significantly diverse in their physiological and biochemical parameters

Salt-tolerant heterotrophic nitrification and aerobic denitrification (HNAD) bacterium enhancing a pilot-scale moving bed biofilm reactor (MBBR) treating mariculture wastewater treatment with different COD/TN ratios

Efficient nitrogen (N) removal from mariculture wastewater is one of the important measures to protect the marine ecological environment. A moving bed biofilm reactor (MBBR) inoculating heterotrophic nitrification and aerobic denitrification (HNAD) bacteria was set and the effects of chemical oxygen demand (COD) and total nitrogen (TN) (COD/TN) ratios on N removal performance, enzymatic activity, biofilm characteristics and microbial community were discussed. Results showed that a more stable N removal performance was obtained in the MBBR process inoculating HNAD bacteria under low COD/TN ratio compared with the conventional MBBR. The removal efficiency of nitrate nitrogen (NO3−-N) declined with COD/TN ratio decrease, and protein (PN) and polysaccharide (PS) concentration decreased from 284.3 and 37.1 mg (g VSS)−1 to 42.9 and 14.4 mg (g VSS)−1 with low ammonia monooxygenase (AMO), nitrite reductase (NIR) and nitrate reductase (NR) activities. Sequencing analysis revealed that strain Zobellella B307 became the dominant microorganism (the relatively abundance is 2.33–5.60 %), and its relatively abundance and the functional genes related to N metabolism reduced from 15.38 % to 9.66 % and 0.61 % to 0.55 % with COD/TN ratio decrease to explain the reason for the decrease of N removal efficiency. This study can provide a deep insight into N removal mechanism of the reactor inoculating HNAD bacteria under different COD/TN ratios.

The impact of short-term nitrogen starvation and replenishment on the nitrate metabolism of hydroponically grown spinach

Nitrate is used as a source of supplemental nitrogen for plants, but it can also contribute to nitrate accumulation in green vegetables, which is unhealthy for humans. This study involves short nitrogen starvation and nitrogen replenishment treatments to minimize the nitrate content in spinach (Spinacea oleracea L.) in order to maximize nitrogen consumption and reduce the nitrate content. For this purpose, five different nitrogen application levels (N0 = 0 mmol·L−1, N4 = 4 mmol·L−1, N8 = 8 mmol·L−1, N12 = 12 mmol·L−1, N16 = 16 mmol·L−1) were used in hydroponic culture, in order to screen out the appropriate nitrogen application level of spinach and carry out short-term nitrogen starvation and replenishment treatment, the nitrate and nitrite contents, nitrate reductase and nitrite reductase activities, nitrate reductase gene and nitrite reductase gene were measured every 5 days, and plant growth was monitored during the experiment together with morphological adaptations at the root level. Our results showed that N8 level of the five nitrogen levels was the most effective for the growth of hydroponic spinach. In contrast to the N8 level, spinach roots and leaves thrive healthier after subsequent short-term nitrogen starvation and replenishment (N8*), optimum nitrate metabolism and key enzymes, and decreased expression levels of NR and NiR genes after nitrogen deprivation, however, their expression increased after nitrogen replenishment. It indicated that NR and NiR genes can be used as a reference gene to reduce the nitrate content in vegetables. In conclusion, our results provided a practical approach for optimum nitrate fertilization that will not only improve spinach growth but also reduce nitrate content harmful for human intake.

Nitric oxide mediates melatonin-induced isoflavone accumulation and growth improvement in germinating soybeans under NaCl stress

The involvement of nitric oxide (NO) in exogenous melatonin (MT)-induced isoflavone accumulation and growth improvement in NaCl-stressed soybeans was investigated in this study. The results demonstrated that MT increased the activity of nitrate reductase (NR) and upregulated the relative expression of NR1, NR2, and nitric oxide synthase1, which subsequently led to an increase in NO content. MT and sodium nitroprusside (SNP, as an NO donor) markedly increased isoflavone content by enhancing the activities of cinnamic acid 4-hydroxylase (C4H) and phenylalanine ammonia lyase (PAL), and by upregulating gene expression of C4H, Isoflavone synthase, PAL, and Chalcone isomerase 1A, which are involved in isoflavone biosynthesis. Moreover, MT, as well as SNP, improved the growth and biomass of NaCl-treated soybeans by increasing the activities of superoxide dismutase, catalase, and peroxidase, and reducing the accumulation of H2O2 and O2•− in soybeans under NaCl stress. These MT-induced responses were entirely reversed by the supply of 4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, a specific scavenger of NO), which in turn considerably decreased endogenous NO content. These results suggest that NO acts as an important downstream signal molecule, mediating MT-induced isoflavone accumulation and growth improvement in NaCl-stressed soybeans.

Physiological performance, yield and quality of crops as influenced by boron

The objective of this investigation was to assess the direct and residual effect of graded levels of boron (B) on growth, yield and quality parameters of crops in cauliflower-cowpea-okra cropping sequence. For this experimentation, cauliflower was grown as a test crop to assess the direct effect of B fertilization while cowpea and okra were grown as succeeding test crop to assess the residual effect of B fertilization. The study revealed an incremental trend in plant physiological and quality parameters corresponding to the escalating B level. Leaf area index (LAI), total chlorophyll content and NR activities in plant leaves and quality parameters, viz. ascorbic acid, protein and starch in edible portion in all crops were found significantly highest with application of 2 kg B/ha. However, on contrary starch content of the crops exhibited an inverse relationship with the higher B application rate wherein depletion of 31.7% of starch content in crops was observed with application of 2 kg B/ha over the control.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background.

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s’ resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.

Nitric oxide is involved in melatonin-induced cold tolerance in postharvest litchi fruit

Previous studies indicate that melatonin, as an important bioactive molecule, appreciably improves cold tolerance in postharvest litchi fruit. However, whether other signaling molecules are involved in melatonin-induced cold tolerance in litchi fruit has not been clarified. In this study, the effect of the interplay between melatonin and nitric oxide (NO) on chilling stress tolerance in relation to redox homeostasis in litchi fruit was investigated. In the first experiment, exogenous applications of melatonin and sodium nitroprusside (SNP) showed similar efficacy in decelerating the development of chilling injury (CI), as indicated by lower CI index and higher retention of pericarp redness in litchi fruit during refrigeration, whereas the opposite effect was found with NO scavenger 2-(4-carboxyphenyl)− 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). The ameliorating effect of melatonin on CI was evidently impaired under cotreatment with melatonin and cPTIO (melatonin + cPTIO). In the second experiment, the biochemical response of litchi fruit to melatonin and melatonin + cPTIO during cold storage was analyzed. The results exhibited that melatonin triggered NO accumulation by activating nitrate reductase (NR) and nitric oxide synthase (NOS) in refrigerated litchi fruit. Melatonin-induced NO accumulation was reduced under treatment with melatonin + cPTIO, but this combined treatment did not affect the NR and NOS activities when compared to melatonin alone. Reactive oxygen species (ROS) in melatonin-treated fruit were markedly quenched by activating antioxidant enzymes and increasing antioxidant metabolite contents, thus alleviating membrane lipid peroxidation and maintaining membrane integrity. Melatonin also led to increased expression of oxidized protein repair-related genes, including LcMsrA1, LcMsrA2, LcMsrB1, LcMsB2, LcTrx2 and LcNTR1. Moreover, an enhanced level of protein S-nitrosylation was observed in fruit upon melatonin treatment. However, the above physiological effect associated with improved fruit cold tolerance afforded by melatonin was partially counteracted by cPTIO. The results suggest that endogenous NO could mediate melatonin-induced cold tolerance in litchi fruit via regulation of redox status.

Exogenous naphthaleneacetic acid alleviated alkalinity-induced morpho-physio-biochemical damages in Cyperus esculentus L. var. sativus Boeck.

Cyperus esculentus L. var. sativus Boeck (commonly called Chufa) is a perennial species that produces nutritious underground tubers and contributes to the diet and health of human worldwide. However, it is salt-sensitive and its adaptation to salinity stress remains an enigma. Naphthaleneacetic acid (NAA) plays a vital role in regulating plant salt stress tolerance. Thus, we aimed to investigate the impact of NAA (150 mg/L) application on growth and physio-biochemical response mechanisms of Chufa plants to different levels of salinity stress (0-, 90-, and 180 mM of alkaline stress ([1:1 ratio of Na2CO3 and NaHCO3]). In response to increasing stress levels, shoot-root growth decreased, whereas malondialdehyde (MDA), hydrogen peroxide (H2O2), osmolytes (soluble protein, proline, and soluble sugars), and activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) significantly increased. Alkalinity led to significant increase in Na+ and Cl-, but decrease in Mg2+ concentration in both roots and leaves; however, K+ decreased significantly in leaves under both stresses. Additionally, and. levels, nitrate reductase (NR) activities, and glutamate synthase (GOGAT) decreased significantly. However, glutamine synthetase (GS) increased non-significantly at 90 mM but declined at 180 mM. Foliar NAA application reduced Na+ and Cl-, MDA, and H2O2 but increased photosynthetic pigments, K+ and Mg2+, osmolytes, nitrogen (N) metabolism, and upregulating the enzymatic antioxidant system to reduce oxidative stress under alkaline conditions. Hence, our findings manifest that NAA application is an effective strategy that can be utilized to enhance tolerance of chufa plants to alkaline stress. Future studies should explore whether NAA can positively alter the nutrient composition of chufa tubers at deeper molecular levels, which might offer solutions to nutritious problems in developing countries.

Gas Emissions and Environmental Benefits of Wheat Cultivated under Different Fertilization Managements in Mollisols

The NH3, N2O and CO2 emissions from farmland soil pose a great threat to the environment, and the application of organic fertilizer and other reasonable fertilization measures can reduce soil gas emissions. However, research into greenhouse gas emissions and environmental benefits under the combined measures of partial substitution of organic fertilizer and phased application of chemical fertilizer is limited. Herein, a field experiment involving soil gas emission monitoring was conducted to study the effects of chemical fertilizer application in stages on Mollisols’ gas emissions and environmental benefits based on the partial replacement of chemical fertilizer with organic fertilizer. Five treatments were set up, including conventional nitrogen application (CF); no nitrogen application (N0); and one-stage (N1), two-stage (N2) and three-stage (N3) application of chemical nitrogen based on 25% of chemical nitrogen being replaced with organic fertilizer. The results showed that N1 had the best emission reduction. Compared with CF, N1 reduced NH3 volatilization and N2O and CO2 emission accumulation by 27.64%, 12.09% and 15.48%, respectively. Compared with N2 and N3, N1 could better reduce the soil urease, nitrate reductase, catalase and β-glucosidase activities, reduce the rate of the conversion of urea and organic carbon, increase the content of NH4+-N in the soil and reduce the NH3 volatilization rate and N2O and CO2 emission rates. A comprehensive analysis showed that N1 showed the best effects in reducing the soil gas emission rate, and environmental cost.

Alleviation of salinity induced growth and photosynthetic decline in wheat due to biochar and jasmonic acid application involves up-regulation of ascorbate-glutathione pathway, glyoxylase system and secondary metabolite accumulation

Combined application of biochar and jasmonic acid for inducing salt stress tolerance in wheat. A 100 mM salt stress was applied fifteen days after germination. biochar (BC, 5%) and jasmonic acid (JA, 5 μM) was applied in individual and in joint applications. The results revealed that growth traits, contents of δ-Amino levulinic acid, glutamate 1-semialdehyde, total chlorophylls and carotenoids, nutrients, nitrate reductase and leaf gas exchange traits were reduced under salt stress. Salt stress increased oxidative stress biomarkers and enzymes of glyoxylase system considerably. It was found that the single and joint application of biochar or jasmonic acid alleviated the decline with maximal alleviation observed in biochar + jasmonic acid treated plants by preventing the oxidative damage and boosting the activities of antioxidant enzymes and enzymes of glyoxylase system. The accumulation of osmolytes and secondary metabolites was more evident under joint biochar and jasmonic acid treatments than individual under NaCl stress. The contents of reducing agents (ascorbate and glutathione) were orchestrated under joint biochar and jasmonic acid application. Nevertheless, the decline in the activity of nitrate reductase and nutrient contents was maximally alleviated under joint application of BC and JA. Therefore, it can be concluded that combined application of biochar and jasmonic acid can be exploited for improved growth and photosynthesis and salinity stress tolerance in wheat and perhaps in other cereal crops.

Aktivitas Nitrat Reduktase (ANR) Tanaman Jagung pada Pola Tumpangsari yang Diberi Serasah Jagung-Kedelai serta Biochar di Lahan Suboptimal Sidondo Sulawesi Tengah

The aim of the study was to examine the relationship between nitrate reductase activity and N uptake, tissue N content, N uptake, and chlorophyll content of corn plants in intercropping patterns which are given corn-soybean litter and biochar. The use of plant litter and biochar derived from crop residues as a source of organic matter in different intercropping patterns affected nitrate reductase activity, tissue N content, N uptake, and chlorophyll content of maize. This experiment was carried out on sub-optimal Sidondo land, Central Sulawesi with the main limiting factors being the availability of water and alkaline soil pH (7.21) which were arranged in a divided plot design with five litter treatments as subplots and five cropping patterns as the main plot with three replicates. Parameters observed were N levels, plant tissue N uptake, chlorophyll, and nitrate reductase activity. Collected data were analyzed using Anova and Duncan's multiple random tests. The results showed that corn litter, soybean mixed corn + soybean litter and their biochar in different intercropping patterns affected nitrate reductase activity, nitrogen uptake, chlorophyll levels very significantly (P˂0.01), increased nitrate reductase activity by 9710.86 mol NO2- -1g-1hour-1 at the age of 55 DAP, while N uptake (2237 mg.kg-1), tissue N content (4.33%), and total chlorophyll content (10.61 mg.l-1) were the highest in the litter treatment, corn and soybeans as well as biochar in corn and soybean intercropping (1:2), and (2:4). Thus, the provision of corn and soybean litter and biochar in intercropping systems can increase nitrate reductase activity, N uptake, tissue N levels, and corn chlorophyll levels in the corn-soybean intercropping system.
 
 Keywords: chlorophyll, N content of corn plant tissue, nitrate reductase activity, N uptake

Pharmaceutical Biotransformation is Influenced by Photosynthesis and Microbial Nitrogen Cycling in a Benthic Wetland Biomat

In shallow, open-water engineered wetlands, design parameters select for a photosynthetic microbial biomat capable of robust pharmaceutical biotransformation, yet the contributions of specific microbial processes remain unclear. Here, we combined genome-resolved metatranscriptomics and oxygen profiling of a field-scale biomat to inform laboratory inhibition microcosms amended with a suite of pharmaceuticals. Our analyses revealed a dynamic surficial layer harboring oxic-anoxic cycling and simultaneous photosynthetic, nitrifying, and denitrifying microbial transcription spanning nine bacterial phyla, with unbinned eukaryotic scaffolds suggesting a dominance of diatoms. In the laboratory, photosynthesis, nitrification, and denitrification were broadly decoupled by incubating oxic and anoxic microcosms in the presence and absence of light and nitrogen cycling enzyme inhibitors. Through combining microcosm inhibition data with field-scale metagenomics, we inferred microbial clades responsible for biotransformation associated with membrane-bound nitrate reductase activity (emtricitabine, trimethoprim, and atenolol), nitrous oxide reduction (trimethoprim), ammonium oxidation (trimethoprim and emtricitabine), and photosynthesis (metoprolol). Monitoring of transformation products of atenolol and emtricitabine confirmed that inhibition was specific to biotransformation and highlighted the value of oscillating redox environments for the further transformation of atenolol acid. Our findings shed light on microbial processes contributing to pharmaceutical biotransformation in open-water wetlands with implications for similar nature-based treatment systems.

Seaweed Extract-based Biostimulant Impacts on Nitrate Reductase Activity and Root Viability of Ultradwarf Bermudagrass Subjected to Heat and Drought Stress

Bermudagrass is a warm-season turfgrass species widely used for sports fields, home lawns, and golf courses. Ultradwarf bermudagrass has been used for golf course greens, but its quality declines with abiotic stresses. This 2-year study was designed to investigate if foliar applications of seaweed extract-based biostimulant Utilize® could improve ultradwarf bermudagrass photosynthetic function, nitrate reductase activity, root growth, and root function while under heat stress and drought stress conditions. Utilize® was applied to ultradwarf bermudagrass canopy at 0, 88, 117, 175, and 234 μL⋅m−2. Two weeks after the initial application of Utilize®, bermudagrass was subjected to heat (40/36 °C, day/night) and drought stress (40–50% evapotranspiration replacement) for up to 42 days. Heat stress and drought stress caused decline of the turf quality. Foliar application of Utilize® at 117, 175, and 234 μL⋅m−2 biweekly consistently improved turf quality and leaf color ratings and increased leaf chlorophyll and carotenoid concentrations, net photosynthetic rate, nitrate reductase activity, and root growth and viability. On average, Utilize® at 117, 175, and 234 μL⋅m−2 increased turf quality ratings by 9.1%, 12.1%, and 10.6%, respectively, net photosynthetic rates by 32.4%, 45.0%, and 35.0%, respectively, and nitrate reductase activity by 16.7%, 18.8%, and 14.6%, respectively, compared with the control. Utilize® at 117, 175, and 234 μL⋅m−2 increased the root biomass, root length, surface area, and root volume compared with the control. Utilize® at 88, 117, 175, and 234 μL⋅m−2 increased root viability by 46.2%, 73.1%, 88.5%, and 74.4%, respectively, relative to the control. The results of this study suggest that seaweed extract-based biostimulant Utilize® improves nitrogen metabolism, photosynthetic function, root growth, and root viability. Foliar application of Utilize® at rates between 117 and 175 μL⋅m−2 biweekly can be considered an effective approach to improving ultradwarf bermudagrass performance under heat stress and drought stress environments.

Complete genome sequencing and analysis revealed the nitrogen utilization strategy of a novel Acuticoccus species isolated from surface water of the Indian Ocean.

Acuticoccus sp. I52.16.1 was isolated from 100m water depth from the Indian Ocean, and presented a novel Acuticoccus species belonging to the family Acuticoccaceae, class Alphaproteobacteria. The strain I52.16.1 displayed the activities of nitrate reductase, nitrite reductase, and urease. The genome of Acuticoccus sp. I52.16.1 consisted of a circular chromosome (5, 134, 086bp) with a G+C content of 69.7mol%. The predicted number of coding genes was 4935, including 6 rRNA, 47 tRNA, and 2 sRNA. The 16S rDNA sequence displayed the maximum similarity of 97.58% with Acuticoccus yangtzensis JL1095T, followed by Acuticoccus sediminis PTG4-2T (97.05%), Acuticoccus kandeliae J103T (96.52%), and Acuticoccus mangrove B2012T (95.85%). Acuticoccus sp. I52.16.1 contained clades of genes involved in assimilating ammonium, nitrate, nitrite, and simple organic nitrogen compounds, but lacked the pathway for dissimilatory denitrification. Two distinct types of ureases were also detected, suggesting genetic heterogeneity. This study provided insight into the nitrogen metabolism strategies of heterotrophic bacteria in the oligotrophic ocean surface.

Effects of drought stress on flowering soybean physiology under different soil conditions

Soybean is highly sensitive to drought stress during its flowering period. Heinong84 (HN84) and Hefeng46 (HF46) were planted in clay loam, silty loam, and sandy clay. We studied the effects of drought stress on the content of membrane lipid peroxides in flowering soybean leaves, the activity of antioxidant enzymes, and the activity of key enzymes of nitrogen metabolism under different soil conditions. Our results showed that soybean had clear physiological responses to drought stress. With increasing drought stress, the malondialdehyde, glutathione reductase, and glutathione peroxidase levels in soybean leaves increased continuously. Superoxide dismutase, peroxidase, glutamine synthase, and glutamate synthase levels increased with drought stress, reaching a maximum under moderate drought stress and then decreased; nitrate reductase activity decreased continuously. Under the condition of sufficient water, the performance of soybean in the three soils is almost the same, but there are differences under drought stress; particularly, soybean grown in clay loam shows the strongest drought resistance. In summary, the physiological state of soybean is easily affected by drought stress, which varies greatly among different cultivars and in different soil types.

Fe(Ⅱ) improving sulfurized Anammox coupled with autotrophic denitrification performance: Based on interspecies and intracellular electron transfer

Insufficient nitrite supply and slow metabolism of Anammox bacteria (AnAOB) impeded the application of Anammox process in low level ammonia (LLA) (≤50 mg/L) wastewater. At the initial concentration of 50 mg/L NH4+-N and 75 mg/L NO3–-N, Fe(Ⅱ) (10 mg/L) promoted the total nitrogen removal efficiency from 80.79 to 94.92 % by core–shell sulfurized AnAOB coupled with sulfur oxidizing bacteria (S0@AnAOB + SOB). AnAOB outcompeted SOB for nitrite, because the addition of Fe(Ⅱ) not only increased the nitrate reductase activity (37.54 %), but also enhanced the metabolism and electron capture ability of AnAOB, which was highly related with energy metabolic process: hydrazine dehydrogenase activity increased to 139.00 %. Particularly, Fe(Ⅱ) accelerated the interspecies electron transfer (INET) (from SOB to AnAOB) by stimulating the secretion of redox species and electron hopping in EPS. This study shed light on the mechanism of Fe(Ⅱ) promoting electron transfer in S0@AnAOB + SOB system, and provided basis for engineering practice.

EVALUATION OF ADVANCED TOMATO MUTANTS BASED ON GROWTH, YIELD ATTRIBUTES AND YIELD

Field experiment was conducted during November 2009 to March 2010, to investigate growth and yield attributes of advanced tomato mutants (TM-110 and TM-219) along with three cultivars (BARI tomato-3, BARI tomato-14 and BINA tomato-5) following randomized complete block design with three replications. There were significant genotypic differences in respect of morpho-physiological characters (plant height, branch and leaf area, total dry mass, absolute growth rate and relative growth rate), biochemical parameter (nitrate reductase), reproductive characters (number of effective and non-effective flower cluster, number of flowers and reproductive efficiency), phenological characters (days to flowering start, days to first harvest and harvesting duration), yield attributes and fruit yield. In general high yielding genotypes showed superior performance in plant height, branch number, leaf area, total dry mass production, absolute growth rate, nitrate reductase activity and fruit size compared to low yielding ones. Relative growth rate,chlorophyll, photosynthesis, reproductive characters and fruit number had no relationship with fruit yield in tomato. The variety BARI tomato-14 showed the highest fruit yield (77.7 t ha-1) due to its superiority in respect of morpho-physiological, biochemical and larger fruit sizes. In contrast, the mutant TM-110 and the variety BINA tomato-5 produced the lower fruit yield (average 51.2 t ha -1) due to poor performance in growth characters and smaller size of fruits. However, TM-110 matured 4-15 days earlier than the other mutant/varieties. Further, harvesting duration was higher in high yielding genotypes than low yielding ones. The highest harvesting duration was recorded in BARI tomato-14 (28 days) followed by BARI tomato-3 (26 days). This information may be implicated in future plant breeding programme.