Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se

Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 μg g⁻¹ soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g⁻¹ soil in raya and maize; 4 μg Se g⁻¹ soil in wheat and 10 μg Se g⁻¹ soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 μg g⁻¹ in raya, 76.9 μg g⁻¹ in maize, 41.5 μg g⁻¹ in rice and 18.9 μg g⁻¹ in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg⁻¹) when the soil was treated with more than 1.5 μg Se g⁻¹. In case of wheat, application of Se more than 3 μg g⁻¹ soil resulted in production of toxic plants.     

Chromium in a series of Portuguese plants used in the herbal treatment of diabetes

Chromium (Cr³⁺) is an essential micronutrient for humans. Its main action is thought to be the regulation of blood sugar, because chromium deficiency is associated with diabetic-like symptoms, and chromium supplementation is correlated with increased glucose tolerance and insulin sensivity. Some Portuguese aromatic plants are utilized as tisanes by diabetic people as medicinal plants. Their active principle is not yet known, and the importance of their chromium content in the claimed therapeutic properties should not be discarded. Therefore, determination of chromium in some Portuguese medicinal plants was performed by flameless atomic absorption. All the analyzed plants contain chromium at the normal level for this element, but the plants used to prepare tisanes to help diabetic conditions contain higher levels (2.2 μg/g dry wt ±0.88;n=11) than the others (0.88 μg/g dry wt±0.18;n=17).     

Somatic embryogenesis and plant regeneration in yakutanegoyou, <Emphasis Type="Italic">Pinus armandii</Emphasis> Franch. var. <Emphasis Type="Italic">amamiana</Emphasis> (Koidz.) Hatusima,an endemic and endangered species in Japan

Induction of somatic embryogenesis in Pinus armandii var. amamiana, an endemic and endangered species in Japan, was initiated from megagametophytes containing immature zygotic embryos on both media with and without plant growth regulators. Across nine open-pollinated families initiation frequency ranged from 0 to 20%, with an average of 1.5%. Embryogenic cultures were maintained and proliferated on a medium supplemented with 2,4-dichlorophenoxyacetic acid (3 μM) and 6-benzylaminopurine (1 μM). Maturation of somatic embryos occurred on medium containing maltose (50 g l⁻¹), activated charcoal (2 g l⁻¹), abscisic acid (100 μM), and polyethylene glycol (100 g l⁻¹). The frequencies of germination and plant conversion of somatic embryos differed among the embryogenic lines from 16 to 51% and from 12 to 40%, respectively. Growth of regenerated somatic plants has been monitored in the field.     

Hyperaccumulation of nickel by two Alyssum species from the serpentine soils of Iran

Serpentine soils, which contain relatively high concentrations of nickel and some other metals, are the preferred substrate for some plants, especially those that accumulate Ni in their tissues. In temperate regions more Ni-hyperaccumulator plants are found in Alyssum than in any other genus. In this study, serpentine soils of two areas (Marivan and Dizaj) in the west/northwest of Iran and also perennial Alyssum plants growing on these soils were analyzed for Ni and some other metals. The highest concentrations of total metals in the soils of these areas for Ni, Cr, Co and Mn were 1,350, 265, 94 and 1,150 μg g⁻¹, respectively, while concentrations of Fe, Mg and Ca reached 3.55%, 16.8% and 0.585% respectively. The concentration of exchangeable Ni in these soils is up to 4.5 μg g⁻¹. In this study two Alyssum species, A. inflatum and A. longistylum, have been collected from Marivan and Dizaj, respectively. Analysis of leaf dry matter shows that they can contain up to 3,700 and 8,100 μg Ni g⁻¹, respectively. This is the first time that such high Ni concentrations have been found in these species. The concentrations of other metals determined in these species were in the normal range for serpentine plants, except for Ca, which was higher, up to 5.3% and 3.5%, respectively     

Shoot multiplication and adventitious regeneration in Sorbus aucuparia

In vitro mother plants initiated from a mature tree of Sorbus aucuparia, produced numerous propagules on a medium containing 2 μM 6-benzylaminopurine (BAP) and 0.2 μM 1-naphthaleneacetic acid (NAA). These were rooted on a medium containing 0.25 μM NAA and 0.25 μM indole−3-butyric acid. Adventitious shoots were produced on excised leaves and internodes on media containing 10 μM thidiazuron and 0.3–1.0 μM NAA. They formed by direct regeneration in the axils of leaflets of intact leaves. They also developed indirectly, from callus that developed on the rachis of intact leaves, and the cut ends of petioles and internodes. Somatic embryos were produced on cotyledons of zygotic embryos on medium containing 1 μM BAP, 1 μM kinetin, 0.5 μM NAA, 500 mg l⁻¹ casein hydrolysate and 250 mg l⁻¹ glutamine. On basal medium, 69% developed cotyledons and 20% germinated after pre-treatment at 4 °C on medium containing 30 g l⁻¹ maltose.     

Availability of Essential Elements in Nutrient Supplements Used as Antidiabetic Herbal Formulations

Five brands of antidiabetic herbal formulations as tablets, Diabetex, Divya Madhu Nashini, Jambrushila, Diabeticin, and Madhumeh Nashini, from different pharmacies were analyzed for six minor (Na, K, Ca, Cl, Mg, and P) and 20 trace (As, Ba, Br, Ce, Co, Cr, Cs, Cu, Fe, Hg, La, Mn, Rb, Sb, Sc, Se, Sm, Th, V, and Zn) elements by thermal neutron irradiation followed by high-resolution gamma ray spectrometry. Further Ni, Cd, and Pb were determined by atomic absorption spectrophotometry. Most elements vary in a narrow range by a factor of 2–4 while a few others vary in a wide range, e.g., Na (0.05–0.67 mg/g), Mn (26.7–250 μg/g), and V (0.26–2.50 μg/g). All the five brands contain K, Cl, Mg, P, and Ca as minor constituents along with mean trace amounts of Cr (2.11 ± 0.67 μg/g), Cu (15.7 ± 7.11 μg/g), Fe (459 ± 171 μg/g), Mn (143 ± 23 μg/g), Se (238 ± 112 ng/g), and V (0.99 ± 0.93 μg/g). Jambrushila is enriched in Na, Ca, Mg, Cl, Fe, Cu, Se, and Zn, essential nutrients responsible for curing diabetes. Dietary intake of Mn, Fe, and Cu are greater than 10% of the recommended dietary allowance, whereas that for Zn and Se is less than 2%. Mean contents of toxic elements (As, Cd, Hg, and Pb) were found below permissible limits except in Jambrushila. Cr and Zn were inversely correlated with r = −0.81, whereas Rb and Cs exhibit linear correlation (r = 0.93) in five brands. C, H, N analysis showed C ∼ 55%, H ∼ 12%, and N ∼ 2% with a total of ∼70% organic matter. However, thermal decomposition studies at 700°C suggest less than 5% nonvolatile metal oxides. Herbal formulations contain minor and trace elements in bioavailable forms that favorably influence glucose tolerance and possibly increase the body’s ability to ameliorate development of diabetes.     

Comparison of Trace Elements in the Scalp Hair of Malignant and Benign Breast Lesions Versus Healthy Women

Trace elements including Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were analyzed in the scalp hair samples of women with malignant breast lesions, women with benign breast lesions, and healthy donors using atomic absorption spectrophotometric method. In the scalp hair of malignant-tumor patients, the highest average concentration was shown by Ca (1,187 μg/g), followed by Na (655 μg/g), Mg (478 μg/g), Zn (391 μg/g), Sr (152 μg/g), Fe (114 μg/g), and K (89.8), while in the case of benign-tumor patients, the average estimated element levels were 1,522, 1,093, 572, 457, 217, 80.4, and 74.7 μg/g, respectively. Most of the elements exhibited non-normal distribution evidenced by large spread, standard error, and skewness values. Mean concentrations of Ca (634 μg/g), Zn (206 μg/g), Mg (162 μg/g), Fe (129 μg/g), and Na (82.1 μg/g) were noteworthy in the scalp hair of healthy women. Average levels of Na, Sr, K, Cd, Co, Pb, Mg, Ca, Zn, Ni, Sb, and Mn were revealed to be significantly higher in the hair of malignant and benign patients compared to the healthy women; however, Fe, Cu, Al, and Cr were not significantly different in the scalp hair of the three groups. The quartile distributions of Ca, Cd, Co, Cr, K, Mg, Mn, Na, Ni, Pb, Sb, and Sr revealed maximum spread in the scalp hair of malignant and benign groups; nevertheless, Al, Cu, Fe, and Zn exhibited almost comparable quartile levels in the three groups. Strong correlation coefficients were found between Fe and Cd, Al and Na, Mn and Sr, Co and Cr, Cd and Cr, Pb and K, Pb and Mn, Cu and Na, and Al and Fe in the scalp hair of malignant-tumor patients, while Fe and K, Cd and Co, Na and Co, and Cr and Pb showed strong correlations in the scalp hair of benign-tumor patients, both of which were significantly different compared with the healthy subjects. Multivariate cluster analysis also revealed divergent clustering of the elements in the scalp hair of malignant and benign patients in comparison with the healthy women.     

Characterization and Distribution of the Selected Metals in the Scalp Hair of Cancer Patients in Comparison with Normal Donors

Eighteen metals were estimated in the scalp hair samples from cancer patients (n = 111) and normal donors (n = 113). Nitric acid–perchloric acid wet digestion procedure was used for the quantification of the selected metals by flame atomic absorption spectrophotometry. In the scalp hair of cancer patients, highest average levels were found for Ca (861 μg/g), followed by Na (672 μg/g), Zn (411 μg/g), Mg (348 μg/g), Fe (154 μg/g), Sr (129 μg/g), and K (116 μg/g), whereas in comparison, the dominant metals in the scalp hair of normal donors were Ca (568 μg/g), Zn (177 μg/g), Mg (154 μg/g), Fe (110 μg/g), and Na (103 μg/g). The concentrations of Ca, Cd, Co, Cr, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were notably higher in the hair of cancer patients as compared with normal donors, which may lead to a number of physiological disorders. Strong positive correlations were found in Mn–Pb (0.83), Cd–Cr (0.82), Cd–Li (0.57), Fe–Pb (0.56), and Fe–Mn (0.55) in the hair of cancer patients whereas Na–Cd, Li–Cr, Li–Co, Co–Cd, Li–Cd, Na–Co, Na–Li, Ca–Mg and Na–Cr exhibited strong relationships (r > 0.50) in the hair of normal donors. Principal Component Analysis (PCA) of the data revealed seven PCs, both for cancer patients and normal donors, but with significantly different loadings. Cluster Analysis (CA) was also used to support the PCA results. The study evidenced significantly different pattern of metal distribution in the hair of cancer patients in comparison with normal donors. The role of trace metals in carcinogenesis was also discussed.     

Comparative studies of nickel,cobalt, and copper uptake by some nickel hyperaccumulators of the genus Alyssum

The uptake of Ni, Co, and Cu by the nickel hyperaccumulator Alyssum troodii Boiss and the non-accumulator Aurinia saxatilis (L.) Desv. were studied in pot trials using artificial rooting media with varying concentrations of the metals added as soluble salts, singly and in combination. The ability of five other Ni hyperaccumulating species of Alyssum to hyperaccumulate Co was also investigated.Leaves and stems of A. troodii accumulated Ni to almost the same extent (8000–10 000 g g^-1). In roots, the highest Ni concentration was 2000 g g^-1. In leaves of Au. saxatilis, the maximum Ni concentration was only 380 g g^-1 and the level in roots was even lower.In media containing Co, the maximum concentration of this element in A. troodii (2325 g g^-1) was ten times higher than in the non-accumulator species. Slightly less Co was found in stems and roots of both species. Among the other Ni hyperaccumulators, the maximum concentration of Co in leaves ranged from about 1000–8000 g g^-1.Copper concentrations were the same in all organs of both species when they were grown in copper-rich media and were in the range 40–80 g g^-1, showing that neither plant was capable of taking up Cu at levels comparable to those of Ni and Co.When both plants were grown in media containing equal amounts of both Co and Ni, the Co concentrations in plant organs were the same as for specimens grown in media containing Co only. However, the Ni levels were lower in both species. Uptake of Co therefore appeared to suppress Ni uptake.Pot trials showed that the order of tolerance was Ni>Cu>Co for A. troodii and Ni>CoCu for Au. saxatilis, whereas the seedling tests showed the order to be Co>Ni>Cu. At metal concentrations 10 000 g g^-1, the overall tolerance of A. troodii was greater than that of Au. saxatilis which exhibited equally low tolerance to Ni and Cu.We conclude that in A. troodii, A. corsicum Duby, A. heldreichii Hausskn., A. murale Waldstein & Kitaibel, A. pintodasilvae T.R. Dudley, and A. tenium Hálácsy, Ni tolerance and hyperaccumulation conveys the same character towards Co. This behaviour should be investigated in other hyperaccumulators of Ni and/or Co.     

A stable and reproducible transformation system for the wetland monocot <Emphasis Type="Italic">Juncus accuminatus</Emphasis> (bulrush) mediated by <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

A highly reproducible Agrobacterium-mediated transformation system was developed for the wetland monocot Juncus accuminatus. Three Agrobacterium tumefaciens binary plasmid vectors, LBA4404/pTOK233, EHA105/pCAMBIA1201, and EHA105/pCAMBIA1301 were used. All vectors contained the 35SCaMV promoter driven, intron containing, β-glucuronidase (gus), and hygromycin phosphotransferase (hptII) genes within their T-DNA. After 48 h of cocultivation, 21-d-old seedling derived calli were placed on medium containing timentin at 400 mg l⁻¹, to eliminate the bacteria. Calli were selected on MS medium containing 40 or 80 mg l⁻¹ hygromycin, for 3 mo. Resistant calli were regenerated and rooted on MS medium containing hygromycin, 5 mg l⁻¹(22.2 μM) of 6-benzylamino-purine (BA) and 0.1 mg l⁻¹(0.54 μM) of alpha-naphthaleneacetic acid (NAA), respectively. Seventy-one transgenic cell culture lines were obtained and 39 plant lines were established in the greenhouse. All the plants were fertile, phenotypically normal, and set viable seed. Both transient and stable expression of the gus gene were demonstrated by histochemical GUS assays of resistant calli, transgenic leaf, root, inflorescence, seeds, and whole plants. The integration of gus and hptII genes were confirmed by polymerase chain reaction (PCR) and Southern analysis of both F₀ and F₁ progenies. The integrated genes segregated to the subsequent generation in Mendelian pattern. To our knowledge, this is the first report of the generation of transgenic J. accuminatus plants.     

Natural Occurrence of Mycotoxins in Staple Cereals from Ethiopia

The occurrence of mycotoxins in barley, sorghum, teff (Eragrostis tef) and wheat from Ethiopia has been studied. Samples were analyzed for aflatoxin B₁ (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) using high performance liquid chromatography (HPLC) and for fumonisins (FUM) using enzyme linked immunosorbent assay (ELISA). AFB1 and OTA were detected in samples of all the four crops. AFB1 was detected in 8.8% of the 352 samples analyzed at concentrations ranging from trace to 26 μg kg⁻¹. OTA occurred in 24.3% of 321 samples at a mean concentration of 54.1 μg kg⁻¹ and a maximum of 2106 μg kg⁻¹. DON occurred in barley, sorghum and wheat at 40–2340 μg kg⁻¹ with an overall incidence of 48.8% among the 84 mainly ‘suspect’ samples analyzed; NIV was co-analyzed with DON and was detected at 40 μg kg⁻¹ in a wheat sample and at 50, 380, and 490 μg kg⁻¹ in three sorghum samples. FUM and ZEN occurred only in sorghum samples with low frequencies at concentrations reaching 2117 and 32 μg kg⁻¹, respectively. The analytical results indicate higher mycotoxin contamination in sorghum, which could be related to the widespread storage of sorghum grain in underground pits leading to elevated seed moisture contents. This is the first report on the occurrence of OTA in teff.     

Rhizosphere competent <Emphasis Type="Italic">Pantoea agglomerans</Emphasis> enhances maize (<Emphasis Type="Italic">Zea mays</Emphasis>) and chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) growth,without altering the rhizosphere functional diversity

Plant growth promoting Pantoea agglomerans NBRISRM (NBRISRM) was able to produce 60.4 μg/ml indole acetic acid and solubilize 77.5 μg/ml tri-calcium phosphate under in vitro conditions. Addition of 2% NaCl (w/v) in the media induced the IAA production and phosphate solubilization by 11% and 7%, respectively. For evaluating the plant growth promotory effect of NBRISRM inoculation a micro plot trial was conducted using maize and chickpea as host plants. The results revealed significant increase in all growth parameters tested in NBRISRM inoculated maize and chickpea plants, which were further confirmed by higher macronutrients (N, P and K) accumulation as compared to un-inoculated controls. Throughout the growing season of maize and chickpea, rhizosphere population of NBRISRM were in the range 10⁷–10⁸ CFU/g soil and competing with 10⁷–10⁹ CFU/g soil with heterogeneous bacterial population. Functional richness, diversity, and evenness were found significantly higher in maize rhizosphere as compared to chickpea, whereas NBRISRM inoculation were not able to change it, in both crops as compared to their un-inoculated control. To the best of our knowledge this is first report where we demonstrated the effect of P. agglomerans strain for improving maize and chickpea growth without altering the functional diversity.     

Induction of Haploid Morphogenic Calluses from in vitro Cultured Anthers of Prunus Armeniaca cv. ‘Harcot’

Apricot (Prunus armeniaca) ‘Harcot’ anthers, were cultured in vitro for the production of haploid plants. The best androgenic response was achieved with Nitsch and Nitsch (1969) medium, supplemented with 4.52 μM 2,4-D, 4.52 μM zeatin, 2.85 μM IAA and 40 g l⁻¹ sucrose. Cultures were maintained in the dark for 8 days, at 28°C, followed by transfer to a 16-h photoperiod, with 35 μm m⁻² s⁻¹ light intensity and 24/22°C day/night temperature. The androgenic response was correlated with the floral bud size, its phenologic stage and the level of microspore evolution. Anthers containing microspores at the tetrad/uninucleate stage were the most appropriate. The ploidy level of the calluses was evaluated by flow cytometry revealing that they range from haploid to octaploid. Mixoploid calluses have also been identified. Histological studies showed that the haploid calluses have their origin in the microspores. Nodular structures consisting of cells with dense cytoplasm and differentiated xylem elements were observed and were surrounded by an autofluorescent layer, probably due to cutin deposition.     

The toxicity of cadmium to barley plants as affected by complex formation with humic acid

An ‘alternating solution’ culture method was used to study the effects of chloride ions and humic acid (HA) on the uptake of cadmium by barley plants. The plants were transferred periodically between a nutrient solution and a test solution containing one of four levels of HA (0, 190, 569 or 1710 μg cm⁻³) and one of five levels of Cd (0, 0.5, 1.0, 2.5 or 5.0 μg cm⁻³) in either a 0.006M NaNO₃ or 0.006M NaCl medium. Harvest and analysis of shoots and roots was after nineteen days. The distribution of Cd in the test solutions between Cd²⁺, CdCl⁺ and HA-Cd was determined in a separate experiment by dialysis equilibrium. In the nitrate test solutions Cd uptake was clearly controlled by Cd²⁺ concentration and was therefore reduced by HA complex formation. In the absence of HA, chloride suppressed Cd uptake indicating that Cd²⁺ was the preferred species. However complex formation with Cl⁻ enhanced uptake when HA was present because of an increase in the concentration of inorganic Cd species relative to the nitrate system. The ratio root-Cd/shoot-Cd remained at about 10 across a wide range of shoot-Cd concentrations, from about 3 μg g⁻¹ (sub-toxic) up to 85 μg g⁻¹ (80% yield reduction). The ability of the barley plants to accumulate ‘non-toxic’ Cd in their roots was thus very limited. Humic acid also had no effect on Cd translocation within the plant and the root/shoot weight ratio did not vary with any treatment. At shoot-Cd concentrations in excess of 50 μg g⁻¹, K, Ca, Cu and Zn uptake was reduced, probably the result of root damage rather than a specific ion antagonism. The highest concentration of HA also lowered Fe and Zn uptake and there was a toxic effect with increasing HA concentration at Cd=0. However the lowest HA level, comparable with concentrations found in mineral soil solutions, only reduced yield (in the absence of Cd) by <5% while lowering Cd uptake across the range of Cd concentrations by 66%–25%.     

Regeneration of <Emphasis Type="Italic">Aeschynanthus radicans</Emphasis> via direct somatic embryogenesis and analysis of regenerants with flow cytometry

Plant regeneration through direct somatic embryogenesis in Aeschynanthus radicans ‘Mona Lisa’ was achieved in this study. Globular somatic embryos were formed directly from cut edges of leaf explants and cut ends or on the surface of stem explants 4 wk after culture on Murashige and Skoog (MS) medium supplemented with N-phenyl-N′-1, 2, 3-thiadiazol-5-ylurea (TDZ) with α-naphthalene acetic acid (NAA), TDZ with 2,4-dichlorophenoxyacetic acid (2,4-D), or 6-benzylaminopurine (BA) or kintin (KN) with 2,4-D. MS medium containing 9.08 μM TDZ and 2.68 μM 2,4-D resulted in 71% of stem explants producing somatic embryos. In contrast, 40% of leaf explants produced somatic embryos when induced in medium containing 6.81 μM TDZ and 2.68 μM 2,4-D. Somatic embryos matured, and some germinated into small plants on the initial induction medium. Up to 64% of stem explants cultured on medium supplemented with 9.08 μM TDZ + 2.68 μM 2,4-D, 36% of leaf explants cultured on medium containing 6.81 μM TDZ and 2.68 μM 2,4-D had somatic embryo germination before or after transferring onto MS medium containing 8.88 μM BA and 1.07 μM NAA. Shoots elongated better and roots developed well on MS medium without growth regulators. Approximately 30–50 plantlets were regenerated from each stem or leaf explant. The regenerated plants grew vigorously after transplanting to a soil-less substrate in a shaded greenhouse with more than a 98% survival rate. Three months after their establishment in the shaded greenhouse, 500 plants regenerated from stem explants were morphologically evaluated, from which five types of variants that had large, orbicular, elliptic, small, and lanceolate leaves were identified. Flow cytometry analysis of the variants along with the parent showed that they all had one identical peak, indicating that the variant lines, like the parent, were diploid. The mean nuclear DNA contents of the variant lines and their parent ranged from 4.90 to 4.99 pg 2C⁻¹, which were not significantly different statistically. The results suggest that the regenerated plants have a stable ploidy level, and the regeneration method established in this study can be used for rapid propagation of ploidy-stable Aeschynanthus radicans.     

Radish plant behaviour under short-term elevated ozone fumigation

Effects of short-term ozone (O₃) fumigation on radish (Raphanus sativus L.) plants were examined in growth chambers under controlled environment conditions. Plants were exposed to 0 μg/m³ (reference), 80 μg/m³, 160 μg/m³ and 240 μg/m³ O₃ concentrations for 7 h per day for five days. Day/night temperature was 21°C/14°C and photoperiod 16 h. Chlorophyll content was evaluated spectrophotometrically. Chromatographic analysis of saccharides was also undertaken. The results showed that elevated O₃ inhibited the growth of radish rhizocarps, net assimilation rate and biomass accumulation. O₃ induced leaf desiccation, necrosis and premature senescence, but a typical reaction of plants to O₃ stress was the rapid regeneration of new leaves. O₃ inhibited accumulation of carotenoids more than chlorophylls. The higher photosynthetic pigment content in newly generated radish leaves may be regarded as an adaptation of the photosynthetic system to O₃. Leaf saccharide metabolism and incorporation depended on O₃ concentration. Rapid regeneration of new leaves and increased content of photosynthetic pigments is the typical reaction of radish plants to O₃ stress.     

Comparison of Trace Element Concentrations in Ambient Air of Industrial and Residential Areas in Tehran City

Tehran is densely populated possessing unhealthy and polluted air. There are 22 municipality districts in Tehran, and considerable numbers of industries are located within each district. Due to adverse environmental and health effects of trace elements in urban air, this study has been carried out to measure and compare concentration of trace elements including Ag, As, Br, Ce, Co, Cr, Cs, Cu, Mn, Hf, La, Sb, Sc, Sm, Th, and Zn in industrial (district 21) and residential (district 22) areas. For this purpose, total suspended particles were collected in two different time intervals in the year 2008. As a result, maximum and minimum concentrations in residential area associated with Mn (2.9 μg/m³) and Hf (2.92 × 10⁻⁴ μg/m³), respectively. Also, in industrial sites, these concentrations are higher for Mn (4.79 × 10⁻¹ μg/m³) and Hf (6.65 × 10⁻⁴ μg/m³). The concentrations of Mn (2.07 μg/m³) and Hf (7.46 × 10⁻⁴ μg/m³) in traffic zone are close to residential values. General, concentrations of Ce, Co, Cs, La, Sc, Sm, Th, Br, and Hf in industrial area were higher than in residential area. The source of these elements in Tehran's air is mainly anthropogenic. According to the achieved results, the concentration levels of As, Cr, and Zn were close together in both residential and industrial zones. Therefore, these elements could have been originated from natural sources. Also, results show that levels of Ag, Mn, Sb, and Cu in residential area were higher than in industrial area. Finally, obtained data indicated that the trends of average concentration of trace elements in industrial area (from low to high) follow as Hf<Cs<Sm<Th<La<Ce<Sc<Co<Ag<As<Sb<Cr<Br<Zn<Cu<Mn and, in residential area, are in order of Hf<Cs<La<Th<Ce<Sc<Sm<Co<As<Ag<Br<Sb<Cr<Zn<Cu<Mn.     

Copper and cobalt in African species ofAeolanthus Mart. (Plectranthinae,Labiatae)

Summary Hyperaccumulators (here defined as species containing at least 500 μg/g dryweight of either copper or cobalt in leaves), are of interest for the fields of mineral exploration and phytochemistry. Reported hyperaccumulation of copper inAeolanthus biformifolius and the presence of two other species on copper/cobalt mineralization in Shaba (Za?re) led to a survey of these elements in 49 species of the African genusAeolanthus Mart.A. biformifolius appears to be also a hyperaccumulator of Co (2520 μg/g in leaves, 4300 μg/g in corms). Cobalt levels for most species ofAeolanthus were considerably above typical values for phanerogams and indicate the favorable potential of the genus for further study.     

Prospecting the utility of a PMI/mannose selection system for the recovery of transgenic sugarcane (<Emphasis Type="Italic">Saccharum</Emphasis> spp. hybrid) plants

For the first time, the phosphomannose isomerase (PMI, EC 5.3.1.8)/mannose-based “positive” selection system has been used to obtain genetically engineered sugarcane (Saccharum spp. hybrid var. CP72-2086) plants. Transgenic lines of sugarcane were obtained following biolistic transformation of embryogenic callus with an untranslatable sugarcane mosaic virus (SCMV) strain E coat protein (CP) gene and the Escherichia coli PMI gene manA, as the selectable marker gene. Postbombardment, transgenic callus was selectively proliferated on modified MS medium containing 13.6 μM 2,4-D, 20 g l⁻¹ sucrose and 3 g l⁻¹ mannose. Plant regeneration was obtained on MS basal medium with 2.5 μM TDZ under similar selection conditions, and the regenerants rooted on MS basal medium with 19.7 μM IBA, 20 g l⁻¹ sucrose, and 1.5 g l⁻¹ mannose. An increase in mannose concentration from permissive (1.5 g l⁻¹) to selective (3 g l⁻¹) conditions after 3 weeks improved the overall transformation efficiency by reducing the number of selection escapes. Thirty-four vigorously growing putative transgenic plants were successfully transplanted into the greenhouse. PCR and Southern blot analyses showed that 19 plants were manA-positive and 15 plants were CP-positive, while 13 independent transgenics contained both transgenes. Expression of manA in the transgenic plants was evaluated using a chlorophenol red assay and enzymatic analysis.     

The effect of phosphite on the sexual reproduction of some annual species of the jarrah (Eucalyptus marginata) forest of southwest Western Australia

Phosphite is a cost-effective fungicide used to control the pathogen Phytophthora cinnamomi which is damaging the diverse flora of the southwest of Western Australia. Three annual species of the southwest jarrah (Eucalyptus marginata) forest of Western Australia (Pterocheata paniculata, Podotheca gnaphalioides and Hyalosperma cotula), were studied to determine the effect of the fungicide phosphite on the species’ reproduction. Phosphite at concentrations of 2.5, 5 and 10 g L^–1 reduced pollen fertility of Pt. paniculata when plants were sprayed at the vegetative stage. Pollen fertility of all three species was reduced when plants were sprayed at anthesis with 10 g L^–1 phosphite. Seed germination was reduced by phosphite in Pt. paniculata and H. cotula when plants were sprayed in the vegetative stage. Phosphite when sprayed at anthesis at a concentration of 5 g L^–1 reduced seed germination of H. cotula. Phosphite at concentrations of 5 and 10 g L^–1 killed a proportion of plants from all three species and up to 90% of Po. gnaphalioides plants. The frequent application of phosphite, therefore, may reduce the abundance of annual plants in this ecosystem. Received: 14 December 2000 / Revision accepted: 10 March 2001