Metal Tolerance of Scented Geranium (Pelargonium sp. ‘Frensham’): Effects of Cadmium and Nickel on Chlorophyll Fluorescence Kinetics

The ability of scented geraniums (Pelargonium sp. Frensham) to tolerate metal stress was assessed using chlorophyll a fluorescence kinetics. The effects of various concentrations of cadmium and nickel in the culture solution on photosynthetic efficiency in scented geranium was evaluated in comparison to two well-established metal accumulators, the Indian mustard (Brassica juncea), and the sunflower (Helianthus annuus), under greenhouse conditions. The efficiency of the photosynthetic apparatus was affected to varying degrees at all metal concentrations for the plants tested. High concentrations of cadmium (1000 mg L^-1) did not significantly affect the efficiency of photosystem II activity, expressed as the ratio of variable fluorescence to maximal fluorescence (Fv/Fm), which remained high (0.738) in scented geraniums, but decreased significantly (P < 0.05) in Indian mustard (0.089) and sunflower (0.026) plants following 4 days of metal exposure. Similar trends were observed for nickel treatments. Also, the number and size of active photosynthetic reaction centers, as measured by the Fv/Fo ratio, was not significantly affected by metal exposure in scented geranium plants, while the ratio significantly decreased in Indian mustard and sunflower seedlings. The results suggest that scented geranium plants were able to overcome metal stress through (1) maintaining an efficient photosystem II activity, which is required for plant metabolism and physiological functions, as well as to overcome metal ion mediated stress, and (2) restricting damage to the photosynthetic apparatus (reaction centers) by metal ions.     

The role of root damage in the chelate-enhanced accumulation of lead by Indian mustard plants

In the present study, increasing ethylenediaminetetraacetic acid (EDTA) concentration from 0 to 0.5 mmol L(-1) resulted in progressive increases in root elongation and in shoot and root dry matter (DM) of Indian mustard seedlings (Brassica juncea. L.) exposed at 0.5 mmol L(-1) of lead (Pb). The highest concentration of Pb in the shoots of Indian mustard reached 1140 mg kg(-1) dry weight (DW) in the treatment with 0.5 mmol L(-1) of Pb + 0.25 mmol L(-1) of EDTA. A significantly positive correlation was found between the concentrations of Pb and EDTA in the shoots of mustard. Roots were pretreated with an MC (methanol:trichloromethane) solution, 0.1 mol L(-1) of HCl, and 65 degrees C hot water. The plants were then exposed to 0.5 mmol L(-1) of Pb + 3 mmol L(-1) of EDTA in solution for 2 d. The pretreatments with MC, HCl, and hot water all increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Therefore, some physiological damage to roots would be useful to enhance the uptake of metal by plants and to minimize the application of doses of chelates in the practical operation of chelate-assisted phytoremediation.     

施肥措施对铅污染土壤中雪里蕻光合特性的影响

通过盆栽试验研究了铅污染土壤上施用有机肥、磷肥和柠檬酸对雪里蕻光合特性的影响.结果表明:不同施肥处理显著提高了雪里蕻的产量、叶绿素含量和对光强的适应范围,均使净光合速率(Pn)、光饱和点(LSP)和表观量子效率(AQY)显著升高,而使光补偿点(LCP)降低;适宜的施肥调控措施可以保持较高的Pn、LSP和AQY,其中施用磷肥获得了最大的Pn、LSP和AQY值.各施肥处理下Fv/Fm的值均大于0.8,均未引起作物光抑制;在不同施肥处理中,高量有机追肥处理可以使叶片PSⅡ的潜在量子效率和PSⅡ原初光能转换效率保持在最高水平.可见,适宜的施肥措施可以显著改善铅污染土壤上雪里蕻的光合特性而促进其生长.     

Dirunal leaf movement, chlorophyll fluorescence and carbon assimilation in soybean grown under different nitrogen and water availabilities

Diurnal heliotropic leaf movements, photosynthetic gas exchange, and the ratio of variable fluorescence to maximum fluorescence (Fv/Fm) of unrestrained and horizontally restrained leaves from soybean (Glycine max cv. Cumberland) plants grown in two different water and two different nitrogen treatments were measured. Leaves of plants grown in low water or low nitrogen availability treatments displayed more pronounced diaheliotropism (solar tracking) in the afternoon and a longer period of paraheliotropism (light avoiding) at midday relative to those of well-watered, high-nitrogen-grown plants. Photosaturated photosynthetic rates and the photon flux required to saturate photosynthesis were reduced by water stress and nitrogen deficiency. Compared to horizontal leaves, irradiance on orienting leaves was nearer to the breakpoint of the photosynthetic light response curve, where photosynthesis is co-limited by ribulose biphosphate regeneration and carboxylation. This would increase the carbon return on investments of nitrogen into photosynthesis. A positive linear relationship between Fv/Fm and quantum yield of photosynthesis was measured. Leaves of low-nitrogen-grown plants had earlier and more prolonged reductions in Fv/Fm at midday compared to leaves of high nitrogen grown plants of the same water treatment. Within the same water and nitrogen treatment, horizontally restrained leaves had lower midday Fv/Fm in relation to orienting leaves. Nitrogen deficiency and water stress enhanced this difference such that horizontally restrained leaves of low water and low nitrogen grown plants had earlier and longer midday depressions in Fv/Fm.     

Effect of dehydration and high light on photosynthesis of two C3 plants (Phaseolus vulgaris L. and Elatostema repens (Lour.) Hall f.)

The effect of drought on the photosynthetic functioning of two C₃ plants, Phaseolus vulgaris and Elatostema repens, has been examined. Leaf net CO₂ uptake measured in normal air was negligible at a leaf water deficit of about 30% while the calculated leaf intercellular CO₂ concentration (Ci) was unchanged. However, both the maximal photosynthetic capacity (CO₂-dependent O₂ evolution) and apparent quantum yield, measured in the presence of saturating CO₂ levels (5 to 14%), only started to decrease within the range of 25 to 30% leaf water deficit. This shows that the drought-induced inhibition seen in normal air is not caused by an inhibition of the photosynthetic mechanism, and that in this case Ci values can be misleading. Both 77 K and room-temperature fluorescence measurements indicate that the functioning of the photosystem-II reaction centre is hardly modified by water shortage. Furthermore, an analysis of photochemical chlorophyll fluorescence quenching shows, in the absence of CO₂, that O₂ can be an efficient acceptor of photosynthetic energy, even in severly dehydrated plants which do not show net CO₂ uptake in normal air. In these plants, O₂ is probably reduced mainly via Mehler-type reactions. High-light treatment given at low O₂ increases photoinhibition as measured by the decrease of apparent quantum yield in dehydrated P. vulgaris, whereas, interestingly, 1% O₂ protects dehydrated E. repens against high-light damage. The two plants could have different protective mechanisms depending upon the O₂ level or different photoinhibitory sites or mechanisms.Abbreviations and symbols Ca, Ci ambient and calculated intercellular CO₂ concentration - Fm, Fo, Fv maximum, initial and variable fluorescence emission - LWD leaf water deficit - PPFD photosynthetic photon flux density - PSII photosystem II - qQ photochemical quenching of chlorophyll fluorescence     

Chemical mutagenesis--a promising technique to increase metal concentration and extraction in sunflowers

Since most of the metal-hyperaccumulating wild plants only produce very low biomass and many high-yielding crops accumulate only moderate amounts of metals, the current research is mainly focused on overcoming these limitations and the optimization of metal phytoextraction. The main goal of the present study was the improvement of metal concentration and extraction properties of Helianthus annuus L by chemical mutagenesis (the non-GMO approach). Sunflowers--hybrid cultivar Salut and inbred lines-were treated with the chemical mutagen ethyl methanesulfonate (EMS). The effect of chemical mutagenesis on metal concentration in and extraction by new sunflower M1 and M2 mutants was directly assessed on a metal-contaminated field in Raft, Switzerland. Mutants of the M2 generation showed a 2-3 times higher metal shoot concentration than the control plants. The best M2 sunflower "giant mutant" 14/185/04 showed a significantly enhanced metal extraction ability: 7.5 times for Cd, 9.2 times for Zn, and 8.2 times for Pb in aboveground parts, as compared to the control plants. Theoretical calculations for the phytoextraction potential of new sunflower variants note that the best sunflower mutant can produce up to 26 t dry matter per hectare and remove 13.3 kg Zn per hectare and year at the sewage sludge contaminated site of Raft; that is a gain factor of 9 compared to Zn extraction by sunflower controls. Furthermore, the use of sunflower oil and biomass for technical purposes (lubricants, biodiesel, biogas) should produce an additional value and improve the economical balance of phytoextraction.     

Efficient Plant Regeneration System From Leaf Discs of Zonal (Pelargonium x hortorum) and two scented (P. capitatum and P. graveolens) Geraniums

An efficient and rapid plant regeneration system was established for zonal and scented geraniums using leaf discs as explants. Several explants, medium and culture conditions were studied to optimize shoot induction. Leaf discs taken from 4–5 weeks old in vitro grown plants, whatever the genotype, were more effective for shoot regeneration than those taken from greenhouse grown plants. Darkness proved to be a stimulating factor for shoot regeneration and the combination between NAA and two cytokinins gave the best results. Direct shoot regeneration (100%) was obtained from leaf discs of P. capitatum on half-strength MS medium supplemented with 0.5 mg l⁻¹ NAA in combination with 1 mg l⁻¹ of BAP and zeatin in darkness (11.4 shoots per explant). In the same medium and culture conditions, all P. graveolens leaf discs also exhibited direct shoot regeneration (7.3 shoots per explant). For P. x hortorum, 100% of leaf discs underwent shoot regeneration on a MS medium supplemented with 0.2 mg l⁻¹ NAA in combination with 0.5 mg l⁻¹ of BAP and zeatin in darkness (8.8 shoots per explant) or under low light conditions with 0.2 mg l⁻¹ NAA and 1 mg l⁻¹ of BAP and zeatin (7.5 shoots per explant). For this species, the best results for shoot elongation were obtained on half-strength MS medium gelled with Phytagel 0.3% (v/v). Whatever the genotype, all shoots rooted readily when transferred to diluted MS medium (MS/2) containing 1 mg l⁻¹ IAA. Acclimatized plants grew normally and flowered in greenhouse conditions. Flow cytometry analysis made on leaves of acclimatized plants revealed that all the scented geranium plants are similar to mother plants while 71% of P. x hortorum plants which showed strong growth were tetraploid.     

Effects of Water Stress and High-Temperature Stress on the Structure and Activity of Photosynthetic Apparatus of Zea Mays and Helianthus Annuus

Effects of high-temperature stress (HTS) and PEG-induced water stress (WS), applied separately or in combination, on the functional activity and ultrastructure of the photosynthetic apparatus (PSA) of maize (Zea mays L.) and sunflower (Helianthus annuus L.) plants were investigated. In maize plant tissues WS provoked the decrease in RWC by 10.9 %, HTS by 7.0 %, and after simultaneous application of the both treatments the decrease was 32.7 % in comparison with control plants. Similar but more expressed changes were observed in sunflower plants. Sunflower was more sensitive to these stresses. Net photosynthetic rate decreased significantly after all treatments, more in sunflower. In mesophyll chloroplasts after separately applied WS and HTS the number of grana and thylakoids was reduced and electron-transparent spaces appeared. At combined stress (WS+HTS) granal and stromal thylakoids were considerably affected and chloroplast envelope in many of them was partially disrupted. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development of photosynthetic apparatus and respiration in pea seedlings during greening as influenced by toxic concentration of lead

Detached leaves of 14 day-old dark-grown pea seedlings were immersed with their cut ends either in water (control) or in 20 mM Pb(NO₃)₂ solution. They were exposed to continuous illumination during 24 and 48 h. The formation of PSII primary photochemistry in thylakoids was determined in vivo by measuring changes in values of parameters of chlorophyll a fast fluorescence kinetics: Fo, Fm, Fv, Fv/Fm and t 1/2. The amount of lead accumulation in leaves, content of chlorophylls and carotenoids and rates of CO₂ uptake in light and evolution in darkness (Pn-net photosynthesis and DR - dark respiration respectively) were determined. It has been found that with the exception of Fo, values of Fv, Fm and Fv/Fm were reduced by Pb²⁺. The values of t 1/2 were significantly larger in Pb²⁺ treated leaves. Decrease in the chlorophyll a fluorescence parameters was paralleled with the strong inhibition by this metal the biosynthesis of chlorophyll a and b but less of the carotenoids. Pb²⁺ drastically reduced Pn but had a stimulatory action on DR after 24 h and small inhibition of DR after 48 h exposure of leaves to this metal. As a consequence, after 48 h of greening the ratio of DR/Pn of control leaves was 0.45 whereas in Pb²⁺ treated leaves 2.7. It is proposed that DR in leaves plays a protective role against damage of Pn by Pb²⁺. Protection can be due to the supply the respiratory derived reductant and ATP to carry out cell metabolism upon reduced photosynthesis.     

Phytoremediation of lead by a wild,non-edible Pb accumulator Coronopus didymus (L.) Brassicaceae

Coronopus didymus was examined in terms of its ability to remediate Pb-contaminated soils. Pot experiments were conducted for 4 and 6 weeks to compare the growth, biomass, photosynthetic efficiency, lead (Pb) uptake, and accumulation by C. didymus plants. The plants grew well having no visible toxic symptoms and 100% survivability, exposed to different Pb-spiked soils 100, 350, 1500, and 2500 mg kg^?1, supplied as lead nitrate. After 4 weeks, root and shoot concentrations reached 1652 and 502 mg Pb kg^?1 DW, while after 6 weeks they increased up to 3091 and 527 mg Pb kg^?1 DW, respectively, at highest Pb concentration. As compared to the 4 week experiments, the plant growth and biomass yield were higher after 6 weeks of Pb exposure. However, the chlorophyll content of leaves decreased but only a slight decline in photosynthetic efficiency was observed on exposure to Pb at both 4 and 6 weeks. The Pb accumulation was higher in roots than in the shoots. The bioconcentration factor of Pb was > 1 in all the plant samples, but the translocation factor was < 1. This suggested C. didymus as a good candidate for phytoremediation of Pb-contaminated soils and can be used for future remediation purposes.     

转C4光合酶基因水稻的CO2交换和荧光特性

用转PEPC、PPDK、NADP-ME、PEPC+PPDK酶基因水稻(Oryza sativa L.)及原种为材料 ,研究了光合作用对光照、温度、CO2的响应和光抑制条件下的叶绿素荧光特性,结果如下: 1.转C4光合酶基因水稻的饱和光合速率比原种高,其中转PEPC、PEPC+PPDK双基因水稻的光饱和点比原种高200 μmol*m-2*s-1,饱和光合速率比原种分别高51.6%和 58.5%;转PEPC基因水稻的羧化效率比原种高49.3%,CO2补偿点降低26.2%;在高温(35 ℃)下,转PEPC基因水稻的光合速率比原种高17.5%.2.经光抑制处理8 d后,转PEPC、PEPC +PPDK酶基因水稻的PSⅡ光化学效率(Fv/Fm)和光化学猝灭(qP)下降20%- 30%,非光化学猝灭(qN)增加了约30%;但原种的Fv/Fm和qP下降了5 0%多,qN变化不明显,表明转C4光合基因水稻耐光抑制能力增强.这些结果为用生物技术提高水稻光合效率研究提供了新的依据和途径.     

Growth and photosynthetic activity of micropropagated strawberry plants inoculated with endomycorrhizal fungi (AMF) and growing under drought stress

The plants produced by in vitro methods are free of any microflora contrary to natural systems where plants are colonized by symbiotic fungi. The present paper reports the experiments carried out to evaluate the role of arbuscular endomycorrhizal fungi in development of micropropagated strawberries and their photosynthetic activity (measured by chlorophyll fluorescence) under drought conditions. Mycorrhization strongly affected growth and tolerance to water deficiency of the plants cultivated in greenhouse. Wilting of not-mycorrhized plants was accompanied by drastic increase of Fo and Tfm and decrease of Fm. At the same time, the value of these parameters for mycorrhized plants did not change. Drastic decrease in the value of parameters Fv/Fm, Fv/Fo and Fo/Fm for plants without AMF appeared at the end of dry period. Rise of Fs and decrease Rfd was noted only for not-mycorrhized plants. The plants colonized by fungi, fully recovered their photosynthetic activity when watering was restored.     

单一与复合污染条件下两种敏感性植物对Cd、Zn、Pb的吸收效应

为了进一步研究镉、锌、铅 3种重金属元素间的相互作用以及对植物吸收重金属能力的影响 ,在模拟单一重金属污染试验研究的基础上 ,采用正交回归设计方案 ,研究了 Cd、Zn、Pb复合污染情况下紫花苜蓿和披碱草两种敏感性植物对 3种重金属的吸收效应。结果表明 ,在单一污染条件下 ,镉元素对紫花苜蓿生长的影响大于锌、铅 ,铅元素对披碱草生长的影响大于锌、镉 ;紫花苜蓿对于镉的吸收累积显著高于披碱草 ,植物内镉元素浓度最高达到 1 0 88.5 mg/kg,而披碱草对于铅元素的吸收则高于紫花苜蓿 ,植物内铅元素浓度最高达到 1 3 4 5 .5 mg/kg。在复合污染条件下 ,两种植物对铅、锌和铅、镉的吸收在不同浓度范围内分别存在存在着协同效应和拮抗效应 ;同时两种植物对锌、镉元素在实验涉及浓度范围内都存在着拮抗效应。这对于深入研究复合污染条件下重金属的土壤环境化学行为 ,对植物的综合毒性以及不同植物对重金属的吸收累积效应等 ,具有一定的参考意义     

Phytoextraction of soil cadmium and zinc by microbes-inoculated Indian mustard (Brassica juncea)

Abstract

A pot experiment was carried out to evaluate the effect of Pseudomonas fluorescens and Trichoderma harzianum inoculation on the uptake of zinc (Zn) and cadmium (Cd) by Indian mustard (Brassica juncea) from the soil having three different concentrations of Zn (300, 600, 900 mg/kg) and Cd (5, 10, 15 mg/kg) separately. Microbial inoculation resulted in significantly better plant growth, available metal content and their uptake than control (without microbes). Available Zn was enhanced, ca.1.6- and 1.4-fold and Cd ca. 2.5- and 1.8-fold, by P. fluorescens and T. harzianum, respectively. P. fluorescens resulted in an increase in Zn uptake by 113.9, 51.9 and 58.4% and T. harzianum by 42.6, 32.1 and 33.9% over control from soils having 300, 600 and 900 mg Zn, respectively, while of the corresponding results for Cd were 110.2, 48.9 and 58.1% with P. fluorescens and 42.6, 30.9 and 33.4% with T. harzianum from soil having 5, 10 and 15 mg Cd, respectively, after 90 days of treatment. In general the rate of metal uptake was higher during the initial 30 days and declined later.     

Performance of rose scented geranium (Pelargonium graveolens) in heavy metal polluted soil vis-à-vis phytoaccumulation of metals

An investigation was carried out to evaluate the effect of heavy metal toxicity on growth, herb, oil yield and quality and metal accumulation in rose scented geranium (Pelargonium graveolens) grown in heavy metal enriched soils. Four heavy metals (Cd, Ni, Cr, and Pb) each at two levels (10 and 20 mg kg–1 soil) were tested on geranium. Results indicated that Cr concentration in soil at 20 mg kg–1 reduced leaves, stem and root yield by 70, 83, and 45%, respectively, over control. Root growth was significantly affected in Cr stressed soil. Nickel, Cr, and Cd concentration and accumulation in plant increased with higher application of these metals. Chromium, nickel and cadmium uptake was observed to be higher in leaves than in stem and roots. Essential oil constituents were generally not significantly affected by heavy metals except Pb at 10 and 20 ppm, which significantly increased the content of citronellol and Ni at 20 ppm increased the content of geraniol. Looking in to the higher accumulation of toxic metals by geranium and the minimal impact of heavy metals on quality of essential oil, geranium can be commercially cultivated in heavy metal polluted soil for production of high value essential oil.     

Effect of lead stress on mineral content and growth of wheat (Triticum aestivum) and spinach (Spinacia oleracea) seedlings

Lead (Pb) is the most common heavy metal contaminant in the environment. Pb is not an essential element for plants, but they absorb it when it is present in their environment, especially in rural areas when the soil is polluted by automotive exhaust and in fields contaminated with fertilizers containing heavy metal impurities. To investigate lead effects on nutrient uptake and metabolism, two plant species, spinach (Spinacia oleracea) and wheat (Triticum aestivum), were grown under hydroponic conditions and stressed with lead nitrate, Pb(NO₃)₂, at three concentrations (1.5, 3, and 15 mM).Lead is accumulated in a dose-dependent manner in both plant species, which results in reduced growth and lower uptake of all mineral ions tested. Total amounts and concentrations of most mineral ions (Na, K, Ca, P, Mg, Fe, Cu and Zn) are reduced, although Mn concentrations are increased, as its uptake is reduced less relative to the whole plant’s growth. The deficiency of mineral nutrients correlates in a strong decrease in the contents of chlorophylls a and b and proline in both species, but these effects are less pronounced in spinach than in wheat. By contrast, the effects of lead on soluble proteins differ between species; they are reduced in wheat at all lead concentrations, whereas they are increased in spinach, where their value peaks at 3 mM Pb.The relative lead uptake by spinach and wheat, and the different susceptibility of these two species to lead treatment are discussed.     

Bioaccumulation and effect of cadmium in the photosynthetic apparatus of Prosopis juliflora

In the present study Prosopis juliflora plants grown in hydroponics solution were exposed to 50,100 and 1000 μM CdCl₂. The cadmium uptake, transport and toxicity on the photosynthetic activities in the plants were measured at 48 h after starting cadmium treatments. The results showed that the concentration of Cd²⁺ in P. juliflora tended to increase with addition of Cd²⁺ to hydroponics solution. However, the increase of Cd²⁺ in roots and leaves varied largely. In this sense, the accumulation of Cd²⁺ in P. juliflora roots increased significantly in proportion with the addition of this metal. In contrast a relatively low level of Cd²⁺ transportation index, and bioaccumulation factor were found in P. juliflora at 48 h after of treatments. On the other hand the maximum photochemical efficiency of photosystem II (Fv/Fm) and the activity of photosystem II (Fv/Fo) ratios in P. juliflora leaf treated with Cd²⁺ not showed significantly changes during the experiment. These results suggested that the photosynthetic apparatus of P. juliflora was not the primary target of the Cd²⁺ action. Further studies will be focused in understanding the participation of the root system in Prosopis plants with the rhizosphere activation and root adsorption to soil Cd²⁺ under natural conditions.     

4种植物对133Cs和88Sr污染土壤的修复研究

以露地盆栽的苏丹草、向日葵、芥菜、萝卜4种植物为对象,研究它们对土壤中不同浓度(0、2.5、5.0、10.0、20.0、40.0mg/kg)133Cs、88Sr的吸收积累状况,并比较它们对133Cs、88Sr污染土壤的修复效率。结果显示:(1)4种植物单株生物量在各浓度处理下均表现为向日葵>萝卜>芥菜>苏丹草,但它们对133Cs的吸收能力为萝卜>苏丹草>向日葵>芥菜,单株133Cs累积量为向日葵>萝卜>苏丹草>芥菜,单株88Sr累积量表现为萝卜、向日葵>苏丹草>芥菜,而且4种植物对88Sr的吸收能力均强于133Cs。(2)萝卜在除10.0mg/kg133Cs外的各处理中富集系数均大于1,对土壤中133Cs的吸收能力较强;苏丹草在除5.0mg/kg133Cs处理外的转运系数均大于1,其余3种植物在各处理中的转运系数均低于1;88Sr在萝卜体内从根系向上转运到地上部分的能力明显高于其它3种植物,芥菜、向日葵次之。(3)4种植物对88Sr在体内向上的迁移转运能力均大于133Cs。研究表明,向日葵单株对133Cs、88Sr污染土壤的修复效率最高,萝卜次之,且向日葵和萝卜分别因其生物量和吸收能力优势而对被污染土壤中的133Cs和88Sr具有更强的提取能力。     

Transgenic Indian mustard (<Emphasis Type="Italic">Brassica juncea</Emphasis>) plants expressing an <Emphasis Type="Italic">Arabidopsis</Emphasis> phytochelatin synthase (<Emphasis Type="Italic">AtPCS1</Emphasis>) exhibit enhanced As and Cd tolerance

Phytochelatins (PCs) are post-translationally synthesized thiol reactive peptides that play important roles in detoxification of heavy metal and metalloids in plants and other living organisms. The overall goal of this study is to develop transgenic plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by expressing an Arabidopsis thaliana AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A FLAG-tagged AtPCS1 gDNA, under its native promoter, is expressed in Indian mustard, and transgenic pcs lines have been compared with wild-type plants for tolerance to and accumulation of cadmium (Cd) and arsenic (As). Compared to wild type plants, transgenic plants exhibit significantly higher tolerance to Cd and As. Shoots of Cd-treated pcs plants have significantly higher concentrations of PCs and thiols than those of wild-type plants. Shoots of wild-type plants accumulated significantly more Cd than those of transgenic plants, while accumulation of As in transgenic plants was similar to that in wild type plants. Although phytochelatin synthase improves the ability of Indian mustard to tolerate higher levels of the heavy metal Cd and the metalloid As, it does not increase the accumulation potential of these metals in the above ground tissues of Indian mustard plants.     

Mycological assisted phytoremediation enhancement of bioenergy crops Zea mays and ‎Helianthus annuus in heavy metal contaminated lithospheric zone

Current investigation has for the first time utilized Trichocomaceae fungi i.e. Aspergillus niger, Aspergillus terreus, Aspergillus flavus and Pencillium i.e. Penicillium chrysogenum for augmenting the phytoremediation potential of bioenergy crops wheat (Zea mays) and ? sunflower (Helianthus annuus). Phytoremediation was done for mitigation of heavy metals i.e. Chromium (Cr), Copper (Cu), Lead (Pb) and Cadmium (Cd) from contaminated soils of agricultural significance. Phytoremediant crops were inoculated with fungal cultures by three methods i.e. mixing method, seed inoculation method and layering spreading method. Maize and sunflower plants after fungal inoculation were harvested after 60 days of germination. The estimation of % biomass and bioenergy of maize and sunflower plants was done. Results were indicative of the good phytoremediation potential of roots and shoots for uptake of heavy metals i.e. CrAspergillus niger, Aspergillus terreus and Aspergillus flavus by fungal inoculation methods. Sunflower and fungal inoculum of Aspergillus flavus and Penicillium chrysogenum extracted significant quantity of metals from the soil. By three fungal inoculation methods, range of % production of biomass was 84?87% and sunflower plants dry biomass 9.6 g yielded 0.16% of oil. Obtained results are have favored the use of fungal inoculation as an effective mode for phytoremediation augmentation of maize and sunflower. Furthermore, current work also signifies the sustainable conversion of bioenergy crops to biofuel production in a cost effective mode.