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Abstract: We recently discovered that atmospheric nitrogen dioxide (N[O.sub.2]) at ambient levels acts as a signal to Nicotiana plumbaginifolia Viviani, causing these plants to double both their biomass and all [...]

Ref.: Re.: Botany, 86: 213-217 (2008). In the above paper, on page 216, an error was inadvertently introduced into the figure (Fig. 1). The correct version follows. [FIGURE 1 OMITTED] [...]

To gain more insight into the physiological function of nitrogen dioxide ( NO2), we investigated the effects of exogenous NO2 on growth in Arabidopsis thaliana., Plants were grown in air without NO2 for 1 wk after sowing and then grown for 1-4 wk in air with (designated treated plants) or without (control plants) NO2. Plants were irrigated semiweekly with a nutrient solution containing 19.7 mM nitrate and 10.3 mM ammonium., Five-week-old plants treated with 50 ppb NO2 showed a ≤ 2.8-fold increase in biomass relative to controls. Treated plants also showed early flowering. The magnitude of the effects of NO2 on leaf expansion, cell proliferation and enlargement was greater in developing than in maturing leaves. Leaf areas were 1.3-8.4 times larger on treated plants than corresponding leaves on control plants. The NO2-induced increase in leaf size was largely attributable to cell proliferation in developing leaves, but was attributable to both cell proliferation and enlargement in maturing leaves. The expression of different sets of genes for cell proliferation and/or enlargement was induced by NO2, but depended on the leaf developmental stage., Collectively, these results indicated that NO2 regulates organ growth by controlling cell proliferation and enlargement. [ABSTRACT FROM AUTHOR]

Assimilatory nitrite reductase (aNiR) reduces nitrite to an ammonium ion and has siroheme and a [Fe4S4] cluster as prosthetic groups. A reaction mechanism for Nii3, an aNiR from tobacco, is proposed based on high resolution X-ray structures and UV-Vis (ultraviolet-visible) microspectroscopy of Nii3-ligand complexes. Analysis of UV-Vis spectral changes in Nii3 crystals with increasing X-ray exposure showed prosthetic group reductions. In Nii3-NO [ABSTRACT FROM AUTHOR]

Production of novel mutants with a high ability to mitigate pollutants is important for phytoremediation. We investigated the use of ion beam irradiation to produce mutants of Ficus pumila L. with an improved ability to mitigate atmospheric nitrogen dioxide (NO2). More than 25,000 shoot explants were irradiated with an ion beam (12C5+, 12C6+, or 4He2+), from which 263 independent plant lines were obtained. The plants were analyzed for NO2 uptake by fumigation with 1 ppm 15N-labeled NO2 for 8 h in light, followed by mass spectrometric analysis. The mean NO2 uptake values of each of the 263 lines differed over a 110-fold range. Propagation was attempted using cuttings from 44 lines showing the greatest NO2 uptake; in total, 15 lines were propagated. Two of the 15 lines showed a mean NO2 uptake 1.7- to 1.8-fold greater than that of the wild-type. This increase in NO2 uptake was heritable in both lines; their progenies showed a significantly greater ability to take up and assimilate NO2 than did the wild-type. RAPD analysis demonstrated DNA variation between the progeny plants and the wild type, suggesting that the progeny were true mutants. These mutants of F. pumila may prove useful in mitigating atmospheric NO2. [ABSTRACT FROM AUTHOR]

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As reported previously, atmospheric nitrogen dioxide (NO2) at an ambient level increased plant size and the contents of cell constituents. We investigated this effect of atmospheric NO2 on decontamination of cadmium (Cd) by kenaf (Hibiscus cannabinus). Seventeen-day-old seedlings of kenaf were grown in air either with NO2 or without NO2. (Plants were exposed to 100 ± 50 ppb NO2 for 10 d under irrigation of 0.1% Hyponex supplemented with 20 μM CdCl2.) Plants were then harvested and the biomass of stems, leaves, and roots, as well as the content of Cd in the organs, was determined. The stem and root biomass per plant were 1.25-1.27-fold greater in +NO2 plants than in -NO2 plants. The Cd content per stem was more than 30% greater in +NO2 plants than in -NO2 plants. [ABSTRACT FROM AUTHOR]

All plants examined to date possess non-symbiotic hemoglobin whose physiological role remains unclear. The present study explored the catalytic function of three representative classes of the plant hemoglobin from Arabidopsis thaliana: AtGLB1, AtGLB2, and AtGLB3. Purified recombinant proteins of these hemoglobins displayed hydrogen peroxide-dependent oxidation of several peroxidase substrates that was sensitive to cyanide, revealing intrinsic peroxidase-like activity. In the presence of nitrite and hydrogen peroxide, AtGLB1 was the most efficient at mediating tyrosine nitration of its own and other proteins via the formation of reactive nitrogen species as a result of nitrite oxidation. AtGLB1 mRNA significantly accumulated in Arabidopsis seedlings exposed to nitrite, supporting the physiological relevance of its function to nitrite and nitrite-derived reactive nitrogen species. [Copyright &y& Elsevier]

In this review, we will describe our study on “nitrogen-philic plants”, which can grow with nitrogen dioxide (NO2) as the sole nitrogen source, by screening of naturally occurring plants for the assimilation of nitrogen dioxide and genetic manipulation of plants for those genes involved in the primary nitrate metabolism. Finally, we will briefly describe “Green walls with nitrogen-dioxide-philic plants” for decontamination of pollution in urban areas. [Copyright &y& Elsevier]

In this short review, basic processes for phytoremediation and plant enzymes that are potentially useful in phytoremediation are briefly summarized. The remaining part describes the applications of the basic processes to decontaminate pollutants in the environments that have been done in our laboratory. Our work includes (1) analysis of the capability of various naturally occurring plants to decontaminate atmospheric nitrogen dioxide and selection of nitrogen-dioxide-philic plants that grow with nitrogen dioxide as the sole nitrogen source, (2) production of transgenic plants to improve plants’ capability to decontaminate atmospheric nitrogen dioxide, and (3) analysis of the denitrification process in plants to innovate a gas–gas-converting plants that convert nitrogen dioxide to nitrogen gas. [Copyright &y& Elsevier]

S–Nitrosoglutathione (GSNO), an adduct of nitric oxide (NO) with glutathione, is known as a biological NO reservoir. Heterologous expression in Escherichia coli of a cDNA encoding a glutathione-dependent formaldehyde dehydrogenase of Arabidopsis thaliana showed that the recombinant protein reduces GSNO. The identity of the cDNA was further confirmed by functional complementation of the hypersensitivity to GSNO of a yeast mutant with impaired GSNO metabolism. This is the first demonstration of a plant GSNO reductase, suggesting that plants possess the enzymatic pathway that modulates the bioactivity and toxicity of NO. [Copyright &y& Elsevier]

Particle bombardment has proved to be useful for the transformation of plants. We have previously reported successful transient expression of the β-glucuronidase (GUS) gene in cultured plant cells and tissues and the stable transformation of various plants using a pneumatic particle gun. In this chapter, we describe transient expression of the GUS gene in Arabidopsis thaliana leaves and roots using the pneumatic particle gun. [ABSTRACT FROM AUTHOR]

Summary: The emission of N[sub 2] and N[sub 2]O from intact transgenic tobacco (clone 271) expressing antisense nitrite reductase (NiR) mRNA, and wild-type plants grown aseptically, on NO[sub 3][sup –], NO[sub 2][sup –] or NH[sub 4][sup +] -containing medium was investigated. [sup 15]N contents of gas sampled from gas-sealed pots, in which the plants were grown on [sup 15]N-containing medium, were analyzed by gas chromato- graphy and mass spectrometry (GC–MS). No emission of N[sub 2] was detected in either of the gas samples from plant clone 271 or the wild-type grown on NO[sub 3][sup –]-containing medium. N[sub 2]O emission from clone 271 grown on NO[sub 3][sup –]-containing medium was detected, but not from the wild-type plants. The N[sub 2]O emission rate of clone 271 was 106 ng N[sub 2]O mg[sup –1] incorporated N week[sup –1] and the N[sub 2]O emission was inhibited by tungstate (a nitrate reductase inhibitor). No emission of N[sub 2]O was found from clone 271 or wild-type plants grown on medium containing NH[sub 4][sup +]. Emission of N[sub 2]O also was detected from clone 271 grown on NO[sub 2][sup –]-containing medium and its emission rate increased with increasing NO[sub 2][sup –] levels in plants. We speculate that NO[sub 3][sup –] is reduced to NO[sub 2][sup –] and that a part of NO[sub 2][sup –] is metabolized to N[sub 2]O in clone 271. [ABSTRACT FROM AUTHOR]

Suspension-cultured cells (A-18 line) of the liverwort Marchanta polymorpha were bombarded by a pneumatic particle gun with plasmid pCH harbouring the hygromycin phosphotransferase (HPT) gene ( hpt) under the control of the cauliflower mosaic virus (CaMV) 35 S promoter and the nopaline synthase polyadenylation region. Nine weeks after bombardments, 128 hygromycin-resistant calluses were obtained from an approximate total of 7×10 cells. Ten cell lines chosen randomly were analysed further. Southern blot analysis showed that all of the ten lines contain the hpt gene in the genome, demonstrating that these lines are transformants. An HPT enzyme activity assay confirmed the expression of the gene in all of the transformant lines. [ABSTRACT FROM AUTHOR]

Immature pollen from Nicotiana rustica was bombarded with gold particles coated with plasmid DNA encoding neomycin phosphotransferase II (NPTII) and β-glucuronidase (GUS) genes which, respectively, are under the control of the cauliflower mosaic virus (CaMV) 35S promoter and nopaline synthase (NOS) terminator in the plasmid. Kanamycin-resistant pollen embryoids were selected from the bombarded pollen cells and two independent lines of transgenic plants were regenerated. Enzyme assays showed that one has both NPTII and GUS activities and the other only weak NPTII activity. Southern blot analyses indicated that the former has a DNA fragment corresponding to the intact expression cassettes for both genes in its genome; whereas the latter lacks intact expression cassettes for both genes and has only the intact nptII coding sequence in its genome. The transgenic plants of both lines have 24 chromosomes, confirming haploidy, and they are infertile. These results indicate that transgenic haploid plants can be produced directly by the bombardment-mediated transformation of immature pollen. [ABSTRACT FROM AUTHOR]