Methyl Jasmonate and Nitrogen Interact to Alleviate Cadmium Stress in Mentha arvensis by Regulating Physio-Biochemical Damages and ROS Detoxification

Journal of Plant Growth Regulation - We examined effects of methyl jasmonate (MeJ), with and without N, for the alleviation of the adverse effects of 150 mg kg−1 CdCl2...     

Effects of dietary copper on growth performance, nutrient digestibility and fiber characteristics in cashmere goats during the cashmere slow-growing period

Thirty-six 2.5-year-old wether Inner Mongolian White Cashmere Goats (IMWG) (BW = 42.7 ± 3.44 kg) were used to determine the effects of dietary copper (Cu) concentration on growth performance, nutrient digestibility and fiber characteristics during the cashmere slow-growing period. Wethers were stratified by weight and randomly assigned to four dietary treatments, which included a control diet containing 5.60 mg Cu/kg DM, the control diet supplied, respectively, with 10, 20 and 30 mg Cu/kg DM (total dietary Cu level of 5.60, 15.6, 25.6 and 35.6 mg/kg DM). The experiment lasted 50 days including a 10-day preliminary trial and 10-day metabolism trial. Average daily feed intake (ADFI) did not differ among treatment groups (P > 0.05), except that the supplement providing 30 mg Cu/kg DM decreased average daily gain and gain efficiency (P < 0.05). Copper supplementation had no influence on digestibility of DM, CP and ADF (P > 0.05), however, NDF digestibility of the treatment group supplemented with 30 mg Cu/kg DM was lower compared with that of other groups (P < 0.05). Length and growth rate of cashmere fiber were higher in the treatment group supplemented with 20 mg Cu/kg DM compared with other groups (P < 0.05), but cashmere diameter was not affected by Cu supplementation (P > 0.05). In conclusion, supplementation of Cu at the levels of 10, 20 and 30 mg/kg DM to the basal diet containing 5.60 mg Cu/kg DM had no influence on ADFI or nutrient digestibility of DM, CP and ADF in cashmere goats, while 30 mg Cu/kg DM supplementation had a negative effect on growth performance and NDF digestibility. However, 20 mg Cu/kg DM supplementation of the basal diet enhanced cashmere growth. Hence, the appropriate supplemental level during the cashmere slow-growing period is deemed to be 20 mg Cu/kg DM (total dietary Cu level of 25.6 mg/kg DM).     

Genome re-diploidization occurs spontaneously just prior to anthesis in artificially induced auto-tetraploid maize (Zea mays L.) inbred lines

Plant Cell, Tissue and Organ Culture (PCTOC) - In this study, various concentrations of oryzalin (0, 5, 10, 50, and 100&nbsp;mg&nbsp;l?1), trifluralin (0, 5, 10, 50, and...     

Elicitor-induced accumulation of stilbenes in cell suspension cultures of Cayratia trifolia (L.) Domin

Cell cultures of Cayratia trifolia (Vitaceae), a tropical lianas, were maintained in Murashige and Skoog’s medium containing 0.25 mg l⁻¹ NAA, 0.2 mg l⁻¹ kinetin and casein hydrolysate 250 mg l⁻¹. Cell suspension cultures of C. trifolia accumulate stilbenes (piceid, resveratrol, viniferin, ampelopsin), which on elicitation by any of 500 μM salicylic acid, 100 μM methyl jasmonate, 500 μM ethrel and 500 mg l⁻¹ yeast extract, added on the 7th day, were enhanced by 3- to 6-fold (5–11 mg l⁻¹) by the 15th day.     

An efficient callus-based in vitro regeneration protocol for Warburgia Ugandensis Sprague,an important medicinal plant in Africa

Warburgia ugandensis Sprague is a woody species in the family Canellaceae and an important source of medicines in Africa. Natural propagation of W. ugandensis is problematic due to its recalcitrant seeds and lack of an efficient in vitro regeneration system for this species. This study describes an efficient regeneration protocol. Petiole bases and shoot tips were used as explants. Callus tissue developed when the explants were cultured on Murashige and Skoog medium containing 30 g L⁻¹ sucrose and 7 g L⁻¹ agar (MS30 medium), supplemented with 1.0 mg L⁻¹ indole-3-butyric acid (IBA), 1.6 mg L⁻¹ 6-benzylaminopurine (BA), and 0.1 mg L⁻¹ thidiazuron (TDZ). Adventitious buds were efficiently induced from the callus when the MS30 medium was supplemented with 0.8 mg L⁻¹ BA and 0.2 mg L⁻¹ IBA. Root induction occurred within 7–10 d on half-strength MS30 medium supplemented with 0.8–1.0 mg L⁻¹ 1-napthalene acetic acid (NAA), 0.2 mg L⁻¹ IBA, and 0.03% (w/v) activated charcoal (AC). Roots were followed by root elongation on the same medium but lacking NAA and IBA. Approximately 50% of the plantlets cultured produced roots, while more than 80% of the plantlets survived and successfully grew to maturity.

     

Dietary Application of the Probiotic Lactobacillus plantarum 426951 Enhances Immune Status and Growth of Rainbow Trout (Oncorhynchus mykiss) Vaccinated Against Yersinia ruckeri

Probiotics and Antimicrobial Proteins - This study was aimed to assess the effect of oral application of Lactobacillus plantarum (2&nbsp;×&nbsp;107&nbsp;CFU&nbsp;g−1...     

High stilbenes accumulation in root cultures of <Emphasis Type="Italic">Cayratia trifolia</Emphasis> (L.) Domin grown in shake flasks

The Root cultures of Cayratia trifolia (Vitaceae) a tropical lianas, were maintained in liquid Murashige and Skoog’s medium containing 0.5 mg l⁻¹ NAA, 0.1 mg l⁻¹ kinetin with 3% sucrose. These root cultures when grown with 6% sucrose accumulated stilbenes (piceid, resveratrol, viniferin, ampelopsin) in high amounts, which on elicitation by 500 mg l⁻¹ yeast extract, 50 μM salicylic acid (SA), 50 μM methyl jasmonate (MeJa), 500 μM ethrel added at 25th day, increased up to ninefolds (7.1 mg l⁻¹). Addition of alar or phenylalanine along with the elicitors further enhanced the stilbenes content. In the present study, stilbenes accumulation up to 12 folds (9.2 mg l⁻¹) was obtained with SA and alar. The SA was the most effective in increasing the stilbenes contents while less than control values were recorded in the cells treated with MeJa. The roots could be grown up to 2 l flasks. The present work demonstrates that presence of precursor and sucrose during elicitation at an appropriate time combined with growth retardation significantly increased the production of stilbenes in C. trifolia cell cultures.     

Morphactin and 2iP markedly enhance accumulation of stilbenes in cell cultures of Cayratia trifolia (L.) Domin

The cell cultures of Cayratia trifolia (Vitaceae) a tropical lianas, were maintained in Murashige and Skoog’s medium containing 0.25 mg l⁻¹ naphthalene acetic acid, 0.2 mg l⁻¹ kinetin and 250 mg l⁻¹ casein hydrolysate. Cell suspension cultures of C. trifolia accumulate stilbenes (piceid, resveratrol, viniferin, ampelopsin) which on addition of 0.1–0.5 mg l⁻¹ morphactin in the medium containing naphthalene acetic acid and kinetin declined. Morphactin or 2 isopentenyl adenine alone at 0.1 mg l⁻¹ concentration enhanced stilbenes which on combination markedly enhanced the yield to ~5 mg l⁻¹ at 15th day.     

Herbal supplementation diets on hematology and innate immunity in goldfish against Aeromonas hydrophila

Goldfish, Carassius auratus (47 ± 3 g, n = 300) were inoculated intramuscularly (50 μl) with Aeromonas hydrophila (1.8 × 10⁶ cells ml^?1). On the 6th day of post-infection the fishes were divided into i) control, without infection fed with normal diet (C), ii) infected fish, fed with normal diet (IU), and infected fishes treated with different doses of iii) 100 mg kg^?1, iv) 200 mg kg^?1, iv) 400 mg kg^?1 and vi) 800 mg kg^?1 mixed herbal extracts supplementation diets. Hematological and immunological parameters were determined on week 1, 2 and 4. In infected goldfish were fed diets containing 100 and 200 mg kg^?1 of mixed herbal extracts supplementation feeds, the white blood cell (WBC) levels significantly increased (P < 0.05) throughout the experimental trial compared to the control. During the experimental period, the red blood cell (RBC) and haemoglobin (Hb) level in goldfish significantly decreased (P < 0.05) when fish fed with 100 and 200 mg kg^?1 of mixed herbal extracts supplementation feeds while it was restored near control when infected fish fed with 400 or 800 mg kg^?1 of herbal extracts supplementation feeds. On the other hand, the haematocrit (Ht) values decline significantly (P < 0.05) in 100, 200 and 400 mg kg^?1 of mixed herbal supplementation feeding groups on weeks 2 and 4 when compared to control group. The mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) values almost significantly differ from the control values. The infected goldfish and treated with 100 or 200 mg kg^?1 of herbal supplementation feeds exhibited significantly decline (P < 0.05) in total protein (TP), glucose (GLU) and cholesterol (CHO) levels on week 1–4 whereas it was restored when infected fish fed with 400 or 800 mg kg^?1 of herbal supplementation feeds on week 4. In comparison to untreated control goldfish, the respiratory burst activity and phagocytic activity of blood cells was significantly enhanced in infected fish feeding with 200, 400 and 800 mg kg^?1 of herbal supplementation feeds compared to the control. On the other hand, infected fish fed with all the doses of mixed herbal supplementation feeds, the lysozyme activity was significantly enhanced throughout the experimental period. This study shows that the infected goldfish treated with 400 and 800 mg kg^?1 of herbal supplementation feeds preceding the challenge with live A. hydrophila had 30% and 25% mortality. However, 100 and 200 mg kg^?1 of herbal supplementation feeds treated groups were found the percentage mortality 50% and 45%, respectively. Our results indicate that 400 or 800 mg kg^?1 of mixed herbal supplementation feeds were restored the altered hematological parameters and triggering the innate immune system of goldfish against A. hydrophila.     

Enhancement of diepoxin ζ production in liquid culture of endophytic fungus <Emphasis Type="Italic">Berkleasmium</Emphasis> sp. Dzf12 by polysaccharides from its host plant <Emphasis Type="Italic">Dioscorea zingiberensis</Emphasis>

This study is the first report of the enhancement of diepoxin ζ production in liquid culture of the endophytic fungus Berkleasmium sp. Dzf12 by the polysaccharides from its host plant Dioscorea zingiberensis which serve as elicitors. Three polysaccharides, namely water-extracted polysaccharide (WEP), sodium hydroxide-extracted polysaccharide and acid-extracted polysaccharide were sequentially prepared from the rhizomes of D. zingiberensis. Among them, WEP was found to be the most effective elicitor to enhance diepoxin ζ production. When WEP was added to the medium at 400 mg l⁻¹ on day 3 of culture, the maximal diepoxin ζ yield (intracellular diepoxin ζ in mycelia plus extracellular diepoxin ζ in medium) of 350.76 mg l⁻¹ on day 15 was achieved, which was about 2.69-fold in comparison with that (130.43 mg l⁻¹) of the control.     

Exposure of preterm neonates to toxic metals during their stay in the Neonatal Intensive Care Unit and its impact on neurodevelopment at 2 months of age

BackgroundPremature neonates might be exposed to toxic metals during their stay in the neonatal intensive care unit (NICU), which could adversely affect neurodevelopment; however, limited evidence is available. The present study was therefore designed to assess the exposure to mercury, lead, cadmium, arsenic, and manganese of preterm neonates who received total parenteral nutrition (TPN) and/or red blood cell (RBC) transfusions during their NICU stay and the risk of neurodevelopment delay at the age of 2 months.MethodsWe recruited 33 preterm neonates who required TPN during their NICU admission. Blood samples were collected for metal analysis at two different time points (admission and before discharge). Metals in the daily TPN received by preterm neonates were analyzed. Neurodevelopment was assessed using the Ages and Stages Questionnaire Edition 3 (ASQ-3).ResultsAll samples of TPN had metal contamination: 96% exceeded the critical arsenic limit (0.3 μg/kg body weight/day); daily manganese intake from TPN for preterm neonates exceeded the recommended dose (1 µg/kg body weight) as it was added intentionally to TPN solutions, raising potential safety concerns. All samples of RBC transfusions exceeded the estimated intravenous reference dose for lead (0.19 µg/kg body weight). Levels of mercury, lead and manganese in preterm neonates at discharge decreased 0.867 µg/L (95% CI, 0.76, 0.988), 0.831 (95%CI, 0.779, 0.886) and 0.847 µg/L (95% CI, 0.775, 0.926), respectively. A decrease in ASQ-3-problem solving scores was associated with higher levels of blood lead in preterm neonates taken at admission (ß = −0.405, 95%CI = −0.655, −0.014), and with plasma manganese (ß = −0.562, 95%CI = −0.995, −0.172). We also observed an association between decreased personal social domain scores with higher blood lead levels of preterm neonates before discharge (ß = −0.537, 95%CI = −0.905, −0.045).ConclusionOur findings provide evidence to suggest negative impacts on the neurodevelopment at 2 months of preterm infants exposed to certain metals, possibly related to TPN intake and/or blood transfusions received during their NICU stay. Preterm neonates may be exposed to levels of metals in utero.     

Significant enhancement of oleanolic acid accumulation by biotic elicitors in cell suspension cultures of Calendula officinalis L.

The effects of elicitors on cell growth and oleanolic acid (OA) accumulation in shaken cell suspension cultures of Calendula officinalis were investigated. Elicitors were added individually at various concentrations to 5-day-old cell cultures and their effects monitored at 24 h intervals for 4 days. Different effects on OA accumulation were observed depending on the day of treatment. Jasmonic acid was the most efficient elicitor. After 72 h of treatment with 100 μM JA, the intracellular content of OA reached its maximum value (0.84 mg g⁻¹ DW), which was 9.4-fold greater than that recorded in an untreated control cultures. The addition of chitosan at 50 mg l⁻¹ produced a 5-fold enhancement of OA accumulation (0.37 mg g⁻¹ DW) after 48 h of treatment. Treatment with yeast extract at 200 mg l⁻¹ for 96 h or with pectin at 2 mg l⁻¹ for 48 h produced identical cellular levels of OA (0.22 mg g⁻¹ DW). Lastly, 48 h elicitation with homogenate of the fungus Trichoderma viride produced a 1.8-fold increase in oleanolic acid content (0.12 mg g⁻¹ DW). In addition to significantly stimulating OA accumulation and its secretion into the culture medium, the elicitors also caused slight inhibition of cell growth.     

Bioremediation of metal contamination in the Plankenburg River,Western Cape,South Africa

Three bioreactors (two laboratory-scale and one on-site) were evaluated for their efficiency to reduce metal concentrations in water collected from the Plankenburg River, South Africa. Water (bioreactors one, two and on-site) and bioballs (bioreactors two and on-site) collected throughout the study periods were digested and analysed using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). Aluminium (Al), nickel (Ni), and zinc (Zn) concentrations decreased from 0.41 mg l^?1 to 0.06 mg l^?1 (85%), 0.2 mg l^?1 to 0.07 mg l^?1 (65%) and 75 mg l^?1 to 0.02 mg l^?1 (97%), respectively (bioreactor one). Aluminium [(1.55–0.38 mg l^?1 (75%)], copper (Cu) [57% (from 0.33 mg l^?1 to 0.14 mg l^?1)], iron (Fe) [71.99–40.4 mg l^?1 (44%)] and manganese (Mn) [57% (0.07–0.03 mg l^?1)] concentrations also decreased in the water samples from bioreactor two. In the on-site, six-tank bioreactor system, concentrations for Fe, Cu, Mn and Ni decreased, while Zn and Al concentrations increased. The concentrations recorded in biofilm samples were higher than the corresponding water samples. The bioballs employed in the bioreactor were thus shown to be efficient attachment surfaces for biofilm development and subsequent metal accumulation. Potentially metal-tolerant organisms (Pseudomonas sp., Sphingomonas sp., and Bacillus sp.) were also identified using phylogeny.     

Optimization and enhancement of soil bioremediation by composting using the experimental design technique

The objective of this study was the application of the experimental design technique to optimize the conditions for the bioremediation of contaminated soil by means of composting. A low-cost material such as compost from the Organic Fraction of Municipal Solid Waste as amendment and pyrene as model pollutant were used. The effect of three factors was considered: pollutant concentration (0.1–2 g/kg), soil:compost mixing ratio (1:0.5–1:2 w/w) and compost stability measured as respiration index (0.78, 2.69 and 4.52 mg O₂ g⁻¹ Organic Matter h⁻¹). Stable compost permitted to achieve an almost complete degradation of pyrene in a short time (10 days). Results indicated that compost stability is a key parameter to optimize PAHs biodegradation. A factor analysis indicated that the optimal conditions for bioremediation after 10, 20 and 30 days of process were (1.4, 0.78, 1:1.4), (1.4, 2.18. 1:1.3) and (1.3, 2.18, 1:1.3) for concentration (g/kg), compost stability (mg O₂ g⁻¹ Organic Matter h⁻¹) and soil:compost mixing ratio, respectively.     

Enhanced stilbene production in cell cultures of <Emphasis Type="Italic">Cayratia trifolia</Emphasis> through co-treatment with abiotic and biotic elicitors and sucrose

This report demonstrates the elicitation effect on growth and stilbene accumulation in cell cultures of Cayratia trifolia (Vitaceae) by an extract of the angiosperm parasite Cuscuta reflexa and salicylic acid in combination with sucrose feeding. Cell cultures of C. trifolia, a tropical liana, were maintained in liquid Murashige and Skoog's basal medium containing 0.25 mg l⁻¹ naphthalene acetic acid, 0.2 mg l⁻¹ kinetin with 3% sucrose and 250 mg l⁻¹ casein hydrolysate. The cells treated with Cuscuta elicitor showed increased polyphenol oxidase activity with increasing concentration of the elicitor, while total phenol content remained almost unchanged. Enhanced yield of stilbenes (∼8-fold) was recorded in the cells treated with 200 mg l⁻¹ Cuscuta elicitor for 7 d. Optimum accumulation of stilbenes with a non-significant decrease in cell growth as compared with control was recorded with the addition of 3% sucrose on the seventh day of cell culture. Addition of 3% sucrose with salicylic acid at 500 μM and Cuscuta extract at 200 mg l⁻¹ on the seventh day enhanced total stilbene yield up to 50.1 mg l⁻¹, which was ∼14-fold higher than in control cultures. Piceid content increased ∼200-fold in such cultures.     

Production of saponions and polysaccharide in the presence of lactoalbumin hydrolysate in <Emphasis Type="Italic">Panax quinquefolium</Emphasis> L. cells cultures

In this article, ginsenosides and polysaccharide contents in suspension cells and native roots of Panax quinquefolium L. were studied. In order to enhance the contents of ginsenosides and polysaccharide in P. quinquefolium suspension cells, we tested the effects of lactoalbumin hydrolysate on the growth of P. quinquefolium suspension cell, synthesis of ginsenosides and polysaccharide in flask and bioreactor. In flask culture, cells growth ratio was significantly enhanced by the addition of lower concentration of lactoalbumin hydrolysate. Addition of 100 mg L⁻¹ lactoalbumin hydrolysate significantly enhanced the contents of total saponins (5.44 mg g⁻¹ DW) and the contents were 3.89-fold over the control group. Addition of lactoalbumin hydrolysate significantly promoted the accumulation of polysaccharide, except 200 mg L⁻¹ lactoalbumin hydrolysate. The highest total saponins yield (36.72 mg L⁻¹ DW) and polysaccharide yield (0.83 g L⁻¹ DW) were obtained at 100 mg L⁻¹ lactoalbumin hydrolysate. In a 5-L stirred tank bioreactor, the highest contents of total saponins and TRb group ginsenosides were achieved on day 26, while the effect of lactoalbumin hydrolysate on the contents of TRg group ginsenosides were insignificant. This result suggests that lactoalbumin hydrolysate might have triggered the enzyme activities for the synthesis of TRb group ginsenosides. Overall, the highest total saponins yield (31.37 mg L⁻¹ DW) and polysaccharide yield (1.618 g L⁻¹ DW) were obtained on day 26 and day 24 respectively and the polysaccharide yield was 1.95-fold higher than the shake flask culture (0.83 g L⁻¹ DW). These results provided theoretical reference for two-stage culture in suspension cells of P. quinquefolium in bioreactor.     

Nitrate removal by a novel autotrophic denitrifier (Microbacterium sp.) using Fe(II) as electron donor

A novel denitrifying bacterium was isolated using bicarbonate as the sole carbon source in a defined medium. Strain W3 was isolated from deep sediments of East Lake (Wuhan, China). In this study, analysis of 16S rRNA genes showed that strain W3 was affiliated with Microbacterium sp. When using Fe2+ as the only electron donor, this strain could convert 88.6 % of NO3 −-N to N2, corresponding to an Fe2+ oxidation rate of 80 %. Meanwhile, neither NO2 −-N nor NH4 +-N was accumulated after the experiment. In similar experiments with Fe(II)-EDTA, cell encrustations did not occur and supplementary substrates were consumed. The accumulated NO2 −-N was below 2.5 mg L−1. In addition, PCR revealed five kinds of key denitrifying genes: narG, napA, nirS, norB and nosZ. These results indicated that strain W3 could be used as an alternative autotrophic denitrifier for the treatment of groundwater and low C/N ratio wastewater.     

A sequencing batch reactor system for high-level biological nitrogen and phosphorus removal from abattoir wastewater

A sequencing batch reactor (SBR) system is demonstrated to biologically remove nitrogen, phosphorus and chemical oxygen demand (COD) to very low levels from abattoir wastewater. Each 6 h cycle contained three anoxic/anaerobic and aerobic sub-cycles with wastewater fed at the beginning of each anoxic/anaerobic period. The step-feed strategy was applied to avoid high-level build-up of nitrate or nitrite during nitrification, and therefore to facilitate the creation of anaerobic conditions required for biological phosphorus removal. A high degree removal of total phosphorus (>98%), total nitrogen (>97%) and total COD (>95%) was consistently and reliably achieved after a 3-month start-up period. The concentrations of total phosphate and inorganic nitrogen in the effluent were consistently lower than 0.2 mg P l⁻¹ and 8 mg N l⁻¹, respectively. Fluorescence in situ hybridization revealed that the sludge was enriched in Accumulibacter spp. (20–40%), a known polyphosphate accumulating organism, whereas the known glycogen accumulating organisms were almost absent. The SBR received two streams of abattoir wastewater, namely the effluent from a full-scale anaerobic pond (75%) and the effluent from a lab-scale high-rate pre-fermentor (25%), both receiving raw abattoir wastewater as feed. The pond effluent contained approximately 250 mg N l⁻¹ total nitrogen and 40 mg P l⁻¹ of total phosphorus, but relatively low levels of soluble COD (around 500 mg l⁻¹). The high-rate lab-scale pre-fermentor, operated at 37°C and with a sludge retention time of 1 day, proved to be a cheap and effective method for providing supplementary volatile fatty acids allowing for high-degree of biological nutrient removal from abattoir wastewater.     

Effects of heavy metals on aerobic denitrification by strain Pseudomonas stutzeri PCN-1

Effects of heavy metals on aerobic denitrification have been poorly understood compared with their impacts on anaerobic denitrification. This paper presented effects of four heavy metals (Cd(II), Cu(II), Ni(II), and Zn(II)) on aerobic denitrification by a novel aerobic denitrifying strain Pseudomonas stutzeri PCN-1. Results indicated that aerobic denitrifying activity decreased with increasing heavy metal concentrations due to their corresponding inhibition on the denitrifying gene expression characterized by a time lapse between the expression of the nosZ gene and that of the cnorB gene by PCN-1, which led to lower nitrate removal rate (1.67∼6.67 mg L⁻¹ h⁻¹), higher nitrite accumulation (47.3∼99.8 mg L⁻¹), and higher N₂O emission ratios (5∼283 mg L⁻¹/mg L⁻¹). Specially, promotion of the nosZ gene expression by increasing Cu(II) concentrations (0∼0.05 mg L⁻¹) was found, and the absence of Cu resulted in massive N₂O emission due to poor synthesis of N₂O reductase. The inhibition effect for both aerobic denitrifying activity and denitrifying gene expression was as follows from strongest to least: Cd(II) (0.5∼2.5 mg L⁻¹) > Cu(II) (0.5∼5 mg L⁻¹) > Ni(II) (2∼10 mg L⁻¹) > Zn(II) (25∼50 mg L⁻¹). Furthermore, sensitivity of denitrifying gene to heavy metals was similar in order of nosZ > nirS ≈ cnorB > napA. This study is of significance in understanding the potential application of aerobic denitrifying bacteria in practical wastewater treatment.

     

Callus induction and plant regeneration in <Emphasis Type="Italic">Dorem ammoniacum</Emphasis> D., an endangered medicinal plant

Dorema ammoniacum D. Don. (Apiaceae), a native medicinal plant in Iran, is classified as a vulnerable species. Root, hypocotyl, and cotyledon segments were cultured on Murashige and Skoog (MS) (1962) medium supplemented with either 2,4-dichlorophenyoxyacetic acid (2,4-D) or naphathalene acetic acid (NAA), at 0–2 mg l⁻¹, alone or in combination with either benzyladenine (BA) or kinetin (KN), at 0–2 mg l⁻¹ for callus induction. The best response (100%) was observed from root segments on MS medium containing 1 mg l⁻¹ NAA and 2 mg l⁻¹ BA. The calli derived from various explants were subcultured on MS medium supplemented with BA (1–4 mg l⁻¹) alone or in combination with NAA or indole-3-butyric acid (IBA), at 0.2 or 0.5 mg l⁻¹ for shoot induction. Calli derived from hypocotyl segments showed significantly higher frequency of plantlet regeneration and number of plantlets than the calli derived from root and cotyledon segments. Therefore, MS medium supplemented with 2 mg l⁻¹ BA and 0.2 mg l⁻¹ IBA produced the highest frequency of shoot regeneration (87.3%) in hypocotyl-derived callus. The optimal medium for rooting contained 2.5 mg l⁻¹ IBA on which 87.03% of the regenerated shoots developed roots with an average number of 5.2 roots per shoots within 30 days. These plantlets were hardened and transferred to the soil. The described method can be successfully employed for the large-scale multiplication and conservation of germplasm this plant.