Successful expression of the synthetic merBps gene in tobacco.

Organomercury is the most toxic biomagnifiable state of mercury, and to date, no natural organomercurial detoxification mechanism is encountered in plants. Bacterial merB gene encoding organomercury lyase show low expression in transgenic plants. For ideal expression, a synthetic merBps gene possessing143 out of 213 codons discrete from native merB gene from Escherichia.

Impact of farm yard manure on cropping cycle in a rainfed agroecosystem of Central Himalaya.

Crops, livestock and forests are interlinked components of Central Himalayan agro-ecosystems. Traditionally, farm yard manure is produced from forest leaf litter and excreta of livestock obtaining > 50% feed from forests. Chemical fertilizers are not used in rainfed farms on slopes.

Light promoted brown staining of protoplasm by Ag+ is ideal to test wheat pollen viability rapidly.

Pollen viability is crucial for wheat breeding programs. The unique potential of the protoplasm of live cells to turn brown due to the synthesis of silver nanoparticles (AgNPs) through rapid photoreduction of Ag+, was exploited for testing wheat pollen viability. Ag+-viability test medium (consisting of 0.

Specific H level is crucial for accurate phosphate quantification using ascorbate as a reductant.

Owing to its essentiality for cellular metabolism, phosphate (PO) plays a pivotal role in ecosystem dynamics. Frequent testing of phosphate levels is necessary to monitor ecosystem health. Present investigations were aimed to identify the key factors that are essential for proper quantification of PO.

Differential sensitivity of light-harnessing photosynthetic events in wheat and sunflower to exogenously applied ionic and nanoparticulate silver.

Potential impacts of inevitable leaks of silver nanoparticles (AgNPs) into environment on human beings need attention. Owing to the vitality of photosynthesis in maintaining life and ecosystem functioning, impacts of exogenously applied nanoparticulate and Ag on photosystem (PS)II function, which governs overall photosynthesis, in wheat and sunflower were evaluated. PSII efficiency and related Chl a fluorescence kinetics of these two plants remained unaffected by AgNPs.

Urea application promotes amino acid metabolism and membrane lipid peroxidation in Azolla.

A pot experiment was conducted to evaluate the effect of urea on nitrogen metabolism and membrane lipid peroxidation in Azolla pinnata. Compared to controls, the application of urea to A. pinnata resulted in a 44% decrease in nitrogenase activity, no significant change in glutamine synthetase activity, 660% higher glutamic-pyruvic transaminase, 39% increase in free amino acid levels, 22% increase in malondialdehyde levels, 21% increase in Na+/K+- levels, 16% increase in Ca2+/Mg2+-ATPase levels, and 11% decrease in superoxide dismutase activity.

Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions.

In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf pondweed () to withstand silver ion (Ag)-toxicity. Both floating and submerged leaves changed clear colorless AgNO solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs) in these brown solutions.

An Environmentally Friendly Engineered Azotobacter Strain That Replaces a Substantial Amount of Urea Fertilizer while Sustaining the Same Wheat Yield.

In our endeavor to improve the nitrogen fixation efficiency of a soil diazotroph that would be unaffected by synthetic nitrogenous fertilizers, we have deleted a part of the negative regulatory gene and constitutively expressed the positive regulatory gene in the chromosome of CBD15, a strain isolated from the local field soil. No antibiotic resistance gene or other foreign gene was present in the chromosome of the engineered strain. Wheat seeds inoculated with this engineered strain, which we have named HKD15, were tested for 3 years in pots and 1 year in the field.

Light Mediated Generation of Silver Nanoparticles by Spinach Thylakoids/Chloroplasts.

The unique potential of chloroplasts/thylakoids to harness light energy to transport electrons from H2O to various entities was exploited for reduction of Ag+ to generate nanoparticles (NPs). Spinach thylakoids/chloroplasts turned AgNO3 solutions brown in light, but not in dark. Besides showing Ag-NPs specific surface plasmon resonance band, these brown solutions showed presence of 5-30 nm crystalline NPs composed of Ag.

A rapid, ideal, and eco-friendlier protocol for quantifying proline.

Proline, a stress marker, is routinely quantified by a protocol that essentially uses hazardous toluene. Negative impacts of toluene on human health prompted us to develop a reliable alternate protocol for proline quantification. Absorbance of the proline-ninhydrin condensation product formed by reaction of proline with ninhydrin at 100 °C in the reaction mixture was significantly higher than that recorded after its transfer to toluene, revealing that toluene lowers sensitivity of this assay.

Impact of ionic and nanoparticle speciation states of silver on light harnessing photosynthetic events in Spirodela polyrhiza.

Owing to wide range of applications, nanotechnology is growing expeditiously. Likely negative impact of nanoparticles (NPs), which are inevitably released into our surroundings, on living organisms is of growing concern. Findings presented here are outcome of investigations carried out to evaluate the impact of ionic and NP speciation states of silver on light harnessing photosynthetic events in Spirodela polyrhiza fronds.

Cadmium toxicity-induced proline accumulation is coupled to iron depletion.

Investigations were conducted to elucidate the key factor behind Cd-toxicity-induced proline accumulation in Indian mustard (Brassica juncea) by raising seedlings, independently in distilled water (DW) and mineral growth medium (MGM) in the presence of 0-500 μM CdCl. Invariably, Cd-induced toxicity, measured in terms of growth, was significantly more prominent in seedlings raised in DW than those raised in MGM. Cd brought about a significant reduction in growth and photosystem II activity with a concomitant increase in proline levels, in a concentration-dependent manner.

Floating and submerged leaves of Potamogeton nodosus exhibit distinct variation in the antioxidant system as an ecophysiological adaptive strategy.

During evaluations of the ecophysiological adaptations of floating and submerged leaves of Potamogeton nodosus Poir, investigations were carried to assess their antioxidant status. Floating leaves possessed a significantly higher level of C skeletons per unit of area compared with submerged leaves as they possessed greater PSI and PSII activity (hence had superior potential to harness absorbed light energy and generate assimilatory power) and carboxylase activity of Rubisco (hence superior potential to fix CO2) compared with the latter. Interestingly, submerged leaves possessed ~2 times higher H2O2 levels compared with floating leaves.

Mitochondrial electron transport protects floating leaves of long leaf pondweed (Potamogeton nodosus Poir) against photoinhibition: comparison with submerged leaves.

Investigations were carried to unravel mechanism(s) for higher tolerance of floating over submerged leaves of long leaf pondweed (Potamogeton nodosus Poir) against photoinhibition. Chloroplasts from floating leaves showed ~5- and ~6.4-fold higher Photosystem (PS) I (reduced dichlorophenol-indophenol → methyl viologen → O2) and PS II (H2O → parabenzoquine) activities over those from submerged leaves.

Reducing strength prevailing at root surface of plants promotes reduction of Ag+ and generation of Ag(0)/Ag2O nanoparticles exogenously in aqueous phase.

Potential of root system of plants from wide range of families to effectively reduce membrane impermeable ferricyanide to ferrocyanide and blue coloured 2,6-dichlorophenol indophenol (DCPIP) to colourless DCPIPH2 both under non-sterile and sterile conditions, revealed prevalence of immense reducing strength at root surface. As generation of silver nanoparticles (NPs) from Ag+ involves reduction, present investigations were carried to evaluate if reducing strength prevailing at surface of root system can be exploited for reduction of Ag+ and exogenous generation of silver-NPs. Root system of intact plants of 16 species from 11 diverse families of angiosperms turned clear colorless AgNO3 solutions, turbid brown.

Can adaptive modulation of traits to urban environments facilitate Ricinus communis L. invasiveness?

This paper addresses the phenotypic variation among Ricinus communis L. populations in four urban habitat types (road verges, garbage dumps, construction debris, and natural area) in Delhi, India, by evaluating important traits such as plant height, basal circumference, seeds per plant, seed size, seed weight, specific leaf area, and reproductive index. An important biochemical marker, proline, considered as a good plant performance indicator under stress was also quantified in leaves of R.

Phenolics impart Au(3+)-stress tolerance to cowpea by generating nanoparticles.

While evaluating impact of Au nanoparticles on seed germination and early seedling growth of cowpea, HAuCl4 was used as control. Seedlings of cowpea raised in HAuCl4, even at concentration as high as 1 mM, did not show any suppression in growth. Accordingly, Au(3+), despite being a heavy metal, did not alter levels of stress markers (viz.

Plants fabricate Fe-nanocomplexes at root surface to counter and phytostabilize excess ionic Fe.

While evaluating the impact of iron nanoparticles (NPs) on terrestrial plants we realized potential of root system of intact plants to form orange-brown complexes constituted of NPs around their roots and at bottom/side of tubes when exposed to FeCl3. These orange-brown complexes/plaques seen around roots were similar to that reported in wetland plants under iron toxicity. Transmission electron microscopy coupled with energy dispersive X-ray analysis revealed that orange-brown complexes/plaques, formed by root system of all 16 plant species from 11 distinct families tested, were constituted of NPs containing Fe.

Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles.

Inbuilt potential of YEM medium and its constituents to generate Ag/Ag₂O nanoparticles.

We discovered that Yeast Extract Mannitol (YEM) medium possessed immense potential to generate silver nanoparticles from AgNO3 upon autoclaving, which was evident from (i) alteration in color of the medium; (ii) peak at ∼410 nm in UV-Vis spectrum due to surface plasmon resonance specific to silver nanoparticles; and (iii) TEM investigations. TEM coupled with EDX confirmed that distinct nanoparticles were composed of silver. Yeast extract and mannitol were key components of YEM medium responsible for the formation of nanoparticles.

Heavy metal induced physiological alterations in Salvinia natans.

Salvinia possess inherent capacity to accumulate high levels of various heavy metals. Accumulation of Cr, Fe, Ni, Cu, Pb and Cd ranged between 6 and 9 mg g(-1)dry wt., while accumulation of Co, Zn and Mn was ∼4 mg g(-1)dry wt.

Physiological and antioxidant responses of Salvinia natans exposed to chromium-rich wastewater.

Salvinia natans possess capacity to accumulate high concentrations of chromium (Cr). Studies were carried out to evaluate physiological efficiency and defensive potential of plant exposed to Cr-rich wastewater. Among photochemical reactions, photosystem I (PS I) and photosystem II (PS II) activity noted an increase in plants exposed to Cr-rich wastewater.

Targeting prokaryotic choline oxidase into chloroplasts enhance the potential of photosynthetic machinery of plants to withstand oxidative damage.

Chloroplasts from plants of transgenic lines expressing prokaryotic choline oxidase gene (the codA(ps) gene; GenBank accession number-AY589052) and wild-type of chickpea and Indian mustard were evaluated for their efficacy to withstand photoinhibitory damage, by exposing them to high light intensity ( approximately 1200micromolm(-2)s(-1) photon flux density) at 10 and 25 degrees C. Western analysis confirmed presence of choline oxidase in chloroplasts of only transgenic lines. The loss in PS II activity in chloroplasts of wild-type exposed to high light intensity was significantly higher than that in chloroplasts of transgenic chickpea as well as Indian mustard.

An optimal protocol for in vitro regeneration, efficient rooting and stable transplantation of chickpea.

A rapid, reproducible and efficient regeneration method was developed for chickpea (Cicer arietinum L.) using single cotyledon with half embryonal axis as explants. MS medium supplemented with 4 ìM TDZ, 10 ìM 2-iP and 2 ìM kinetin induced 50-100 adventitious buds/shoots after 14 days of culture and elongated on MS medium supplemented with 5 ìM 2-iP and 2 ìM kinetin.

Sugars have potential to curtail oxygenase activity of Rubisco.

Sugars play a critical role in regulating overall cellular metabolism and owing to their general compatibility with various cellular events plants invariably show enhanced levels of sugars for maintaining desired osmoticum under osmotic stress. Sugars (sucrose and trehalose) and sugar-alcohols (glycerol, mannitol, inositol, and sorbitol) with the exception of sorbitol lowered oxygenase activity of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase, EC 4.1.