Assessment of photosynthetic potential of indoor plants under cold stress

Photosynthetic parameters including net photosynthetic rate (P_N), transpiration rate (E), water-use efficiency (WUE), and stomatal conductance (g_s) were studied in indoor C₃ plants Philodendron domesticum (Pd), Dracaena fragans (Df), Peperomia obtussifolia (Po), Chlorophytum comosum (Cc), and in a CAM plant, Sansevieria trifasciata (St), exposed to various low temperatures (0, 5, 10, 15, 20, and 25°C). All studied plants survived up to 0°C, but only St and Cc endured, while other plants wilted, when the temperature increased back to room temperature (25°C). The P_N declined rapidly with the decrease of temperature in all studied plants. St showed the maximum P_N of 11.9 μmol m^?2 s^?1 at 25°C followed by Cc, Po, Pd, and Df. E also followed a trend almost similar to that of P_N. St showed minimum E (0.1 mmol m^?2 s^?1) as compared to other studied C₃ plants at 25°C. The E decreased up to ≈4-fold at 5 and 0°C. Furthermore, a considerable decline in WUE was observed under cold stress in all C₃ plants, while St showed maximum WUE. Similarly, the g_s also declined gradually with the decrease in the temperature in all plants. Among C₃ plants, Pd and Po showed the maximum g_s of 0.07 mol m^?2 s^?1 at 25°C followed by Df and Cc. However, St showed the minimum g_s that further decreased up to ～4-fold at 0°C. In addition, the content of photosynthetic pigments [chlorophyll a, b, (a+b), and carotenoids] was varying in all studied plants at 0°C. Our findings clearly indicated the best photosynthetic potential of St compared to other studied plants. This species might be recommended for improving air quality in high-altitude closed environments.     

Bacterial metabolites from intra- and inter-species influencing thermotolerance: the case of <Emphasis Type="Italic">Bacillus cereus</Emphasis> and <Emphasis Type="Italic">Geobacillus stearothermophilus</Emphasis>

Bacterial metabolites with communicative functions could provide protection against stress conditions to members of the same species. Yet, information remains limited about protection provided by metabolites in Bacillus cereus and inter-species. This study investigated the effect of extracellular compounds derived from heat shocked (HS) and non-HS cultures of B. cereus and Geobacillus stearothermophilus on the thermotolerance of non-HS vegetative and sporulating B. cereus. Cultures of B. cereus and G. stearothermophilus were subjected to HS (42 or 65 °C respectively for 30 min) or non-HS treatments. Cells and supernatants were separated, mixed in a combined array, and then exposed to 50 °C for 60 min and viable cells determined. For spores, D values (85 and 95 °C) were evaluated after 120 h. In most cases, supernatants from HS B. cereus cultures added to non-HS B. cereus cells caused their thermotolerance to increase (D ₅₀ 12.2–51.9) when compared to supernatants from non-HS cultures (D ₅₀ 7.4–21.7). While the addition of supernatants from HS and non-HS G. stearothermophilus cultures caused the thermotolerance of non-HS cells from B. cereus to decrease initially (D ₅₀ 3.7–7.1), a subsequent increase was detected in most cases (D ₅₀ 18–97.7). In most cases, supernatants from sporulating G. stearothermophilus added to sporulating cells of B. cereus caused the thermotolerance of B. cereus 4810 spores to decline, whereas that of B. cereus 14579 increased. This study clearly shows that metabolites in supernatants from either the same or different species (such as G. stearothermophilus) influence the thermotolerance of B. cereus.     

Effects of low nocturnal temperature on photosynthetic characteristics and chloroplast ultrastructure of winter rapeseed

We investigated the effects of low nocturnal temperature on photosynthetic apparatus of winter rapeseed (Brassica campestris L.). An artificial climate chamber was used to simulate the effects of low nocturnal temperature on seedling and stomatal morphology, chloroplast ultrastructure, photosynthetic parameters, and dry matter distribution and accumulation in two winter rapeseed cultivars, Longyou-7 (ultra coldresistant) and Tianyou-2 (weak cold resistance). Compared with those at diurnal/nocturnal temperatures of 20°/10°C (control), rapeseed seedlings at 20°/5°C had increased leaf chlorophyll content, deepened green leaf color, decreased stomatal conductance (G_s), intercellular CO₂ concentration (C_i), and photosynthetic rate (P_n), and improved root/shoot ratio; the majority of stomata remained open in Longyou-7 while those in Tianyou-2 were mostly closed or semi-closed. At diurnal/nocturnal temperatures of 20°/–5°C, rapeseed seedlings had decreased leaf chlorophyll content with increased C_i but decreased G_s and P_n; Tianyou-2 exhibited ruptured chloroplast membrane, dissolved grana, broken stroma lamella, and decreased root/shoot ratio, whereas Longyou-7 had chloroplasts retaining partial structure of grana with a small amount of starch granules in guard cells. Low nocturnal temperature damaged the photosynthetic membrane of chloroplasts and reduced P_n in the leaves of winter rapeseed influencing photosynthetic processes in this crop. The reduction of P_n was mainly related to stomatal limitation at diurnal/nocturnal temperatures of 20°/5°C and non-stomatal limitation at diurnal/nocturnal temperatures of 20°/–5°C.     

Isolation of the chitin-glucan complex from the fruiting bodies of mycothallus

A four-stage procedure for the isolation of the ChGC from the biomass of natural fungi—the honey mushroom (Armillariella mellea) and the yellow morel (Morchella esculenta), belonging to the classes Basidiomycetes and Ascomycetes, respectively, has been developed. The isolation procedure included deproteinization (2% NaOH + 0.1% sodium stearate, 83–85°C, 2 h), demineralization (1% HCl, 55–60°C, 2 h), depigmentation (5% H₂O₂ in ammonia (30–35°C, 4 h)), and deglucanization (2% NaOH, 83–85°C, 2 h). The original raw material and the chitin-containing materials were characterized on the basis of results of Fourier transform infrared spectroscopy, X-ray analysis, and pyrolytic gas chromatography using crustacean chitin as a reference compound. The content of chitin in the final products was 70% for A. mellea and 50% for M. esculenta. The possibility of obtaining chitin-containing materials with the required properties by selecting the fungal species and treatment conditions (the succession and repetition of certain stages) is demonstrated.     

Biodegradation of <Emphasis Type="Italic">n</Emphasis>-alkanes on oil–seawater interfaces at different temperatures and microbial communities associated with the degradation

Oil biodegradation studies have mainly focused on microbial processes in dispersions, not specifically on the interfaces between the oil and the seawater in the dispersions. In this study, a hydrophobic adsorbent system, consisting of Fluortex fabrics, was used to investigate biodegradation of n-alkanes and microbial communities on oil–seawater interfaces in natural non-amended seawater. The study was performed over a temperature range from 0 to 20 °C, to determine how temperature affected biodegradation at the oil–seawater interfaces. Biodegradation of n-alkanes were influenced both by seawater temperature and chain-length. Biotransformation rates of n-alkanes decreased by reduced seawater temperature. Low rate coefficients at a seawater temperature of 0 °C were probably associated with changes in physical–chemical properties of alkanes. The primary bacterial colonization of the interfaces was predominated by the family Oceanospirillaceae at all temperatures, demonstrating the wide temperature range of these hydrocarbonoclastic bacteria. The mesophilic genus Oleibacter was predominant at the seawater temperature of 20 °C, and the psychrophilic genus Oleispira at 5 and 0 °C. Upon completion of n-alkane biotransformation, other oil-degrading and heterotrophic bacteria became abundant, including Piscirickettsiaceae (Cycloclasticus), Colwelliaceae (Colwellia), Altermonadaceae (Altermonas), and Rhodobacteraceae. This is one of a few studies that describe the biodegradation of oil, and the microbial communities associated with the degradation, directly at the oil–seawater interfaces over a large temperature interval.     

Biology and Thermal Requirements of <Emphasis Type="Italic">Fopius arisanus</Emphasis> (Sonan, 1932) (Hymenoptera: Braconidae) Reared on <Emphasis Type="Italic">Ceratitis capitata</Emphasis> Eggs (Wiedemann) (Diptera: Tephritidae)

Fopius arisanus (Sonan) is a solitary parasitoid of eggs and the first instar larvae of Tephritidae. Due to the occurrence of Ceratitis capitata (Wiedemann) in various regions and under several climatic conditions, this study aimed to evaluate the effect of different temperatures on the embryonic development (egg–adult) and determine thermal requirements and the number of annual generations F. arisanus on eggs of C. capitata. In the laboratory, eggs of C. capitata (24 h) were submitted to parasitism of F. arisanus during 6 h. Later, the eggs were placed in plastic containers (50 mL) (50 eggs/container) on a layer of artificial diet and packed in chambers at temperatures 15, 18, 20, 22, 25, 28, 30, and 32 ± 1°C, RH 70 ± 10%, and a photophase of 12 h. The largest number of offspring, emergence rate, and weight of adults of F. arisanus were observed at 25°C. The highest sex ratios (sr > 0.75) were recorded at 15 and 18°C, being statistically higher than the temperatures 20°C (0.65), 22°C (0.64), 25°C (0.65), 28°C (0.49), and 30°C (0.47). At 32°C, there was no embryonic development of F. arisanus. The egg–adult period was inversely proportional to temperature. Based on the development of the biological cycle (egg–adult), the temperature threshold (T _t) was 10.3°C and thermal constant (K) of 488.34 degree-days, being the number of generations/year directly proportional to the temperature increase. The data show the ability of F. arisanus to adapt to different thermal conditions, which is important for biological control programs of C. capitata.     

Thermotolerant oil-degrading bacteria isolated from soil and water of geographically distant regions

Oil-degrading bacteria were isolated from soil and water samples taken in Russia, Kazakhstan, and the Antarctic; 13 of 86 strains proved to be thermotolerant. These bacteria utilized crude oil at 45–50°C; their growth optimum (35–37°C) and range (20–53°C) differ from those of mesophilic bacteria. Thermotolerant strains were identified as representatives of the genera Rhodococcus and Gordonia. It was shown that their ability to degrade petroleum products does not differ at 24 and 45°C. The strains Rhodococcus sp. Par7 and Gordonia sp. 1D utilized 14 and 20% of the oil, respectively, in 14 days at 45°C. All of the isolated thermotolerant bacteria grew in a medium containing 3% NaCl; the medium for the strains Gordonia amicalis 1B and Gordonia sp. 1D contained up to 10% NaCl. The bacteria G. amicalis and Rhodococcus erythropolis were able to utilize crude oil and individual hydrocarbons at higher (up to 50°C) temperatures.     

Purification and Characterization of a Novel (<Emphasis Type="Italic">R</Emphasis>)-1-Phenylethanol Dehydrogenase from <Emphasis Type="Italic">Lysinibacillus</Emphasis> sp. NUST506

A novel (R)-1-phenylethanol dehydrogenase was successfully purified from Lysinibacillus sp. NUST506 by preparative polyacrylamide gel electrophoresis. The enzyme is a NAD+-dependent oxidoreductase. The molecular weight of the (R)-1-phenylethanol dehydrogenase measured by SDS-PAGE was about 28 kDa. Furthermore, the optimal reaction conditions for the oxidative reaction were 70°C and pH 9.5 and for the reductive reaction were 65°C and pH 6.5. Under the optimal conditions, the K_M and k_cat values with (R)-1-phenylethanol as a substrate were found to be 0.78 mM and 123 s^–1 and with acetophenone they were 0.56 mM and 125 s^–1, respectively. The (R)-1-phenylethanol dehydrogenase became more stable at pH 9.5 in comparison with pH 5.0 and high stability was noticed at 4 and 37°C. Properties of the enzyme place it as a promising candidate for industrial applications.     

<Emphasis Type="Italic">Gallaecimonas mangrovi</Emphasis> sp. nov., a novel bacterium isolated from mangrove sediment

A Gram-stain negative, rod-shaped, non-motile, strictly aerobic bacterium HK-28^T was isolated from a mangrove sediment sample in Haikou city, Hainan Province, China. Strain HK-28^T was able to grow at 10–45 °C (optimum 25–30 °C), pH 5.0–8.5 (optimum 6.0–7.0) and 0.5–12.0% (w/v) NaCl (optimum 1.0–3.0%, w/v). The major cellular fatty acids were C_16:0, Summed Feature 8 (C_18:1 ω7c and/or C_18:1 ω6c), Summed Feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_17:0, C_12:0 3-OH and C_17:1ω8c. Ubiquinone-8 (Q-8) was the predominant respiratory quinone. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, four unidentified phospholipids, two unidentified glycolipid, an unidentified glycophospholipid, an unidentified aminolipid and an unidentified lipid. The DNA G+C content was 50.2 mol%. Accoroding to 16S rRNA gene sequence similarities, strain HK-28^T shared 97.1 and 96.7% sequence similarities to the validly named species Gallaecimonas xiamenensis MCCC 1A01354^T and Gallaecimonas pentaromativorans MCCC 1A06435^T, respectively, and shared lower sequence similarities (<?92.0%) to all other genera. Phylogenetic analysis showed strain HK-28^T was clustered with G. pentaromativorans MCCC 1A06435^T and G. xiamenensis MCCC 1A01354^T. Strain HK-28^T showed low DNA–DNA relatedness with G. xiamenensis MCCC 1A01354^T (28.3?±?1.5%) and G. pentaromativorans MCCC 1A06435^T (25.2?±?2.4%). On the basis of phenotypic, chemotaxonomic and genotypic characteristics, strain HK-28^T is considered to represent a novel species in the genus Gallaecimonas, for which the name Gallaecimonas mangrovi sp. nov. is proposed. The type strain is HK-28^T (=?KCTC 62177^T?=?MCCC 1K03441).     

<Emphasis Type="Italic">Roseomonas aeriglobus</Emphasis> sp. nov., isolated from an air-conditioning system

A novel pale pink-coloured, strictly aerobic, Gram-stain negative bacterial strain, designated strain KER25-12^T, was isolated from a laboratory air-conditioning system in South Korea. Cells were observed to be non-motile cocci showing positive catalase and oxidase reactions. Strain KER25-12^T was found to grow at 10–30 °C (optimum, 25–30 °C), at pH 4.0–9.0 (optimum, pH 6.0–7.0) and in the presence of 0–2% (w/v) NaCl (optimum, 0%). Ubiquinone-10 and spermidine were detected as the sole respiratory quinone and the predominant polyamine, respectively. The major fatty acids were identified as summed feature 8 (comprising C_18:1 ω7c and/or C_18:1 ω6c), summed feature 3 (comprising C_16:1 ω7c and/or C_16:1 ω6c), C_16:0 and C_18:0. The genomic DNA G+C content of strain KER25-12^T was determined to be 70.0 mol%. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unidentified aminolipid. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain KER25-12^T belongs to the genus Roseomonas and shows high sequence similarity to Roseomonas aerilata 5420S-30^T (98.57%), Roseomonas pecuniae N75^T (97.44%) and Roseomonas vinacea CPCC 100056^T (97.40%). Based on the morphological, physiological, chemotaxonomic and phylogenetic features, strain KER25-12^T is concluded to represent a novel species of the genus Roseomonas, for which the name Roseomonas aeriglobus sp. nov. is proposed. The type strain is KER25-12^T (= KACC 19282^T = JCM 32049^T).     

The cloning,expression, and comparative analysis of peroxiredoxin 6 from various sources

Human, rat, Xenopus, and Drosophila (DPx2540 and DPx6005) peroxiredoxin cDNAs were cloned and expressed in Escherichia coli. The recombinant enzymes were compared with respect to enzymatic activity toward various substrates and protection of plasmid DNA from the Fenton reaction products. The activity toward H₂O₂ decreased in the following order: DPx2540 > human Prx6 > Xenopus Prx6 > rat Prx6 > DPx6005. The activity toward tret-butyl hydroperoxide decreased in the following order: DPx2540 = DPx6005 > rat Prx6 > Xenopus Prx6 > human Prx6. The efficiency of plasmid DNA protection from oxidative damage mediated by the Fenton reaction decreased in the order of DPx2540 > DPx6005 = rat Prx6 = human Prx6 > Xenopus Prx6. The optimal temperature for activity of all enzymes was 37°C. Peroxiredoxins from rat, Xenopus, and Drosophila (DPx6005) retained no less than 50% of their activity in a wider temperature range (10–50°C) as compared with the human and Drosophila (DPx2540) enzymes (25–45°C). The thermostability of the enzymes decreased in the following order: DPx6005 = rat > human > Xenopus > DPx2540. The results confirmed a negative correlation between the activity and stability of peroxiredoxin 6, especially in the case of the Xenopus and Drosophila enzymes.     

Temperature-induced changes in treatment efficiency and microbial structure of aerobic granules treating landfill leachate

This paper investigates the effect of temperature on nitrogen and carbon removal by aerobic granules from landfill leachate with a high ammonium concentration and low concentration of biodegradable organics. The study was conducted in three stages; firstly the operating temperature of the batch reactor with aerobic granules was maintained at 29 °C, then at 25 °C, and finally at 20 °C. It was found that a gradual decrease in operational temperature allowed the nitrogen-converting community in the granules to acclimate, ensuring efficient nitrification even at ambient temperature (20 °C). Ammonium was fully removed from leachate regardless of the temperature, but higher operational temperatures resulted in higher ammonium removal rates [up to 44.2 mg/(L h) at 29 °C]. Lowering the operational temperature from 29 to 20 °C decreased nitrite accumulation in the GSBR cycle. The highest efficiency of total nitrogen removal was achieved at 25 °C (36.8 ± 10.9 %). The COD removal efficiency did not exceed 50 %. Granules constituted 77, 80 and 83 % of the biomass at 29, 25 and 20 °C, respectively. Ammonium was oxidized by both aerobic and anaerobic ammonium-oxidizing bacteria. Accumulibacter sp., Thauera sp., cultured Tetrasphaera PAO and Azoarcus–Thauera cluster occurred in granules independent of the temperature. Lower temperatures favored the occurrence of denitrifiers of Zooglea lineage (not Z. resiniphila), bacteria related to Comamonadaceae, Curvibacter sp., Azoarcus cluster, Rhodobacter sp., Roseobacter sp. and Acidovorax spp. At lower temperatures, the increased abundance of denitrifiers compensated for the lowered enzymatic activity of the biomass and ensured that nitrogen removal at 20 °C was similar to that at 25 °C and significantly higher than removal at 29 °C.     

An NADPH-dependent <Emphasis Type="Italic">Lactobacillus composti</Emphasis> short-chain dehydrogenase/reductase: characterization and application to (<Emphasis Type="Italic">R</Emphasis>)-1-phenylethanol synthesis

A new anti-Prelog short-chain dehydrogenase/reductase (SDR) encoding gene lcsdr was cloned from Lactobacillus composti DSM 18527, and heterologously expressed in Escherichia coli. LcSDR is nicotinamide adenine dinucleotide phosphate (NADPH)-dependent and has a molecular weight of approximately 30 kDa. The optimal pH and temperature were 6.5 and 30?°C, respectively. The maximal reaction rate V_max was 133.9 U mg^?1; the Michaelis–Menten constant K _m of LcSDR were 0.345 mM for acetophenone (1a), and 0.085 mM for NADPH. Through introducing an EsGDH-catalyzed NADPH regeneration system, a biocatalytic process for (R)-1-phenylethanol ((R)-1b) was developed with outstanding time–space yield. Under the optimized conditions, 50 g l^?1 1a was converted to (R)-1b in 2 h with a yield of 93.8%, enantiomeric excess of product (e.e._p) above 99% and space–time yield of 562.8 g l^?1 d^?1.     

Jasmonic acid regulates the ascorbate–glutathione cycle in <Emphasis Type="Italic">Malus baccata</Emphasis> Borkh. roots under low root-zone temperature

Jasmonic acid (JA), which is an important phytohormone, plays a key role in plant growth, development and stress responses. Here, Malus baccata Borkh. seedlings were used to study the mechanism by which JA alleviates the oxidative damage induced by low root-zone temperature (5 °C) through regulating the ascorbate–glutathione (AsA–GSH) cycle. The roots of M. baccata Borkh. were subjected to three treatments [5 °C, 5 °C + JA, and 5 °C + ibuprofen (IBU)] for 0, 12, 24, and 48 h. The results showed that treatment with low root-zone temperature could modulate the non-enzymatic and enzymatic components of the AsA–GSH cycle, significantly inducing the accumulation of MDA and H₂O₂. Additionally, the endogenous JA content changed dramatically, and the expression levels of the related genes [lipoxygenase (LOX), allene oxide synthase (AOS), and allene oxide cyclase (AOC)] showed different trends. In plants pretreated with JA, the endogenous JA content increased at 24 h, and the gene expression levels of LOX, AOS, and AOC were upregulated. We also found a marked increase in the activities of antioxidant enzymes [ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR)], a decrease in oxidized glutathione (GSSG) and an increased GSH/GSSG ratio, which resulted in lower MDA and H₂O₂ contents. Thus, the oxidative stress was alleviated. Plants pretreated with IBU experienced an opposite effect on the function of the AsA–GSH cycle and the gene expression in the JA synthesis route relative to those subjected to exogenous JA treatment, indicating that endogenous JA can alleviate oxidative damage by regulating the function of the AsA–GSH cycle under low root-zone temperature.     

Hydrothermal time analysis of watermelon (<Emphasis Type="Italic">Citrullus vulgaris</Emphasis> cv. ‘Crimson sweet’) seed germination

This study evaluated the ability of a hydrothermal time model (HTT) to describe the kinetics of watermelon (Citrullus vulgaris cv. ‘Crimson sweet’) seed germination under different temperatures (T) and water potentials (ψ) and also to determine the cardinal temperatures of watermelon. Results indicated that ψ influenced germination rate and germination percentage. For this seed lot, cardinal temperatures were 10 °C for T _b, 28.34 °C for T _o and 40.8 °C for T _c in the control (0 MPa) treatment. There was a decrease in hydrotime constant (θ _H) when T was increased to T _o and then remained constant at supra-optimal temperatures (30 MPah^?1). Also, at temperatures above T _o, ψ _b(50) values increased linearly with T. The k _T value (the slope of the relationship between ψ _b(50) and T exceeds T _o) of this seed lot was calculated as 0.076 MPa°Ch^?1. Results this study show that when the HTT model is applied, it can accurately describe ψ _b(g) and the course of germination around Ts (R ² = 0.82). Moreover, the ψ _b(50) was estimated to be ?0.96 MPa based on this model. Consequently, the germination response of watermelon for all Ts and ψs can be adequately described by the HTT model and enabling it to be used as a predictive tool in watermelon seed germination simulation models.     

<Emphasis Type="Italic">Spirosoma luteolum</Emphasis> sp. nov. isolated from water

A novel Gram-negative and rod-shaped bacterial strain, designated as 16F6E^T, was isolated from a water sample. Cells were yellowish in color and catalase- and oxidase-positive. The strain grew at 10–37°C (optimum at 25°C) but not at 4 and 42°C, and pH 5–7 (optimum at pH 7). It showed moderate resistance to gamma-ray irradiation. Comparative phylogenetic analysis showed that strain 16F6E^T belonged to the family Cytophagaceae of the class Cytophagia. Furthermore, this isolate showed relatively low 16S rRNA gene sequence similarities (90.7–93.1%) to the members of the genus Spirosoma. The major fatty acids were summed feature 3 (C_16:1 ω7c/C_16:1 ω6c), C_16:1 ω5c, C_16:0 N alcohol, and C_16:0. The polar lipid profile indicated presence of phosphatidylethanolamine, unknown aminophospholipids, an unknown amino lipid, unknown phospholipids, and unknown polar lipids. The predominant isoprenoid quinone was MK-7. The genomic DNA G+C content of strain 16F6E^T was 56.5 mol%. Phenotypic, phylogenetic, and chemotaxonomic properties indicated that isolate 16F6E^T represents a novel species within the genus Spirosoma, for which the name Spirosoma luteolum sp. nov. is proposed. The type strain is 16F6E^T (=KCTC 52199^T =JCM 31411^T).     

Using hydrothermal time concept to describe sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) seed germination response to temperature and water potential

To quantify both temperature (T) and water potential (ψ) effects on sesame (Sesamum indicum L.) seed germination (SG) and also to determine the cardinal T _s for this plant, a laboratory experiment was carried out using hydrothermal time model (HTT). For this purpose, four sesame cultivars (‘Asbomahalleh’, ‘Darab’, ‘Dashtestan’ and ‘Yellowhite’) were germinated at seven constant T _s (20, 25, 30, 35, 37, 39 and 43 °C) at each of the following ψ _s (0, ? 0.12, ? 0.24 and ? 0.36 MPa; provided by PEG 8000). Germination rate (GR) and germination percentage (GP) significantly influenced by ψ, T and their interactions in all cultivars (P ≤ 0.01). There was no significant difference, based on the confidence intervals of the model coefficients, between cultivars, so an average of cardinal T _s was 14.7, 35.4 and 47.2 °C for the minimum (T _b), optimum (T _o) and maximum (T _c) T _s, respectively, in the control condition (0 MPa). Hydrotime values in all cultivars decreased when T was increased to T _o and then remained constant at T _s > T _o (15 MPa h^?1). An average value of ψ _b(50) was estimated to be ? 1.23 MPa at T _s ≤ T _o and then increased linearly (0.1041 MPa°Ch^?1, the slope of the relationship between ψ _b(50) and supra-optimal T _s) with T when T _s increased above T _o and finally reached to zero at T _c. The T _b and T _o values were not influenced by ψ, but T _c value decreased (from 47.2 for zero to 43.5 °C for ? 0.36 MPa) at supra-optimal T _s as a result of the effect of ψ on GR. Based on our findings, this model (as a predictive tool) and or the estimated parameter values in this study can easily be used in sesame SG simulation models to quantitatively characterize the physiological status of sesame seed populations at different T _s and ψ _s.     

Modeling seed germination of unprimed and primed seeds of sweet sorghum under PEG-induced water stress through the hydrotime analysis

The effects of reduced water potential (ψ) on seed germination at 25 and 15 °C in unprimed (UP) and primed (P) seeds of two cultivars of sweet sorghum (cv. Keller and cv. Makueni local), were analyzed through the hydrotime model. Six ψ (from 0 to ?1.0 MPa) in polyethylene glycol 6000 (PEG) solutions were used for the tests. Seeds were primed in 250 g/L PEG solution at 15 °C for 48 h. Decreasing ψ of imbibition solution reduced and delayed germination. At 15 °C seeds germinated less and slower than at 25 °C at any ψ. Seeds of cv. Makueni local exhibited a greater sensitivity to water stress in terms of germination percentage, than seeds of cv. Keller, but they were faster in germination. Osmopriming was beneficial for seed germination, both in terms of final percentage and rate, at any temperature and ψ. The hydrotime analysis revealed that predicted θ _H constant was increased when temperature was reduced to 15 °C and at this temperature median base water potential [ψ _b(50)] for germination was higher (less negative) than at 25 °C. Seed priming shifted ψ _b(50) towards more negative values and reduced θ _H requirements for germination. At 25 °C the two cultivars behaved similarly while at 15 °C cv. Keller exhibited a ψ _b more negative but required a greater θ _H to germinate, indicating a greater water-stress tolerance but a slower germination, than cv. Makueni local. The application of the model allows to identify water stress tolerant cultivars during germination, to include into breeding programs for the selection of well-performing cultivars under stress conditions.     

Earthworm Communities in the Bamboo Plantations of West Tripura (India)

Present study revealed the presence of 16 earthworm species belonging to 11 genera and four families viz. Megascolecidae (Amynthus alexandri, Metaphire houlleti, Lampito mauritii, Kanchuria sp1, Perionyx excavatus), Octochaetidae (Eutyphoeus gigas, Eutyphoeus comillahnus, Eutyphoeus orientalis, Octochaetona beatrix, Dichogaster bolaui, Lennogaster chittagongensis, Lennogaster yeicus), Moniligastridae (Drawida papillifer papillifer, Drawida assamensis, Drawida nepalensis) and Glossoscolecidae (Pontoscolex corethrurus) in the soils of five bamboo species [Bambusa balcooa (Sil Barak), Melocanna baccifera (Muli), Bambusa polumorpha (Bari), Bambus cacharensis (Bom) and Bambus bambus (Katabarak)] of West-Tripura. While four earthworm species viz. Metaphire houlleti, Drawida assamensis, Drawida papillifer papillifer and Pontoscolex corethrurus were common to all species of bamboo plantations, the rest showed restricted distribution. Among the earthworm species 4 were exotic (Amynthus alexandri, Metaphire houlleti, Dichogaster bolaui and Pontoscolex corethrurus) and the others were native to the Indian sub-continent. In general, earthworms under the bamboo plantations occurred within temperature range of 21.6 °C–28.0 °C, pH 4.0–7.0, organic matter 0.56–5.99 %, moisture 9.6–31.7 %, water holding capacity 14.6–43.9 % and bulk density 0.7–1.8 g cm^?3. The average density and biomass of the earthworms in the studied places were 108 ind m^?2 and 44 g m^?2 respectively. Earthworm diversity, dominance and evenness indices showed the values 1.00, 0.47 and 0.70 respectively. Earthworm density and biomass showed a negative correlation with temperature whereas those had a strong positive correlation with pH, moisture and organic matter of the soils.     

Characterization flavanone 3β-hydroxylase expressed from <Emphasis Type="Italic">Populus euphratica</Emphasis> in <Emphasis Type="Italic">Escherichia coli</Emphasis> and its application in dihydroflavonol production

Flavanone 3β-hydroxylase plays very important role in the biosynthesis of flavonoids. A putative flavanone 3β-hydroxylase gene (Pef3h) from Populus euphratica was cloned and over-expressed in Escherichia coli. Induction performed with 0.1 mM IPTG at 20°C led to localization of PeF3H in the soluble fraction. Recombinant enzyme was purified by Ni-NTA affinity. The optimal activity of PeF3H was revealed at pH 7.6 and 35°C. The purified enzyme was stable over pH range of 7.6–8.8 and had a half-life of 1 h at 50°C. The activity of PeF3H was significantly enhanced in the presence of Fe²⁺ and Fe³⁺. The K _M and V _max for the enzyme using naringenin as substrate were 0.23 mM and 0.069 μmoles mg–1min-1, respectively. The K _m and V _max for eriodictyol were 0.18 mM and 0.013 μmoles mg^–1min^–1, respectively. The optimal conditions for naringenin bioconversion in dihydrokaempferol were obtained: OD₆₀₀ of 3.5 for cell concentration, 0.1 mM IPTG, 5 mM α-ketoglutaric acid and 20°C. Under the optimal conditions, naringenin (0.2 g/L) was transformed into 0.18 g/L dihydrokaempferol within 24 h by the recombinant E. coli with a corresponding molar conversion of 88%. Thus, this study provides a promising flavanone 3β-hydroxylase that may be used in biosynthetic applications.