The Arabidopsis defensin gene AtPDF2.5 mediates cadmium tolerance and accumulation

Although excess cadmium (Cd) accumulation is harmful to plants, the molecular mechanisms underlying Cd detoxification and accumulation in Arabidopsis thaliana remain largely undetermined. In this study, we demonstrated that the A. thaliana PLANT DEFENSIN 2 gene AtPDF2.5 is involved in Cd tolerance and accumulation. In vitro Cd‐binding assays revealed that AtPDF2.5 has Cd‐chelating activity. Site‐directed mutagenesis of AtPDF2.5 identified eight cysteine residues that were essential for mediating Cd tolerance and chelation. Histochemical analysis demonstrated that AtPDF2.5 was mainly expressed in root xylem vascular bundles, and that AtPDF2.5 was significantly induced by Cd. Subcellular localization analysis revealed that AtPDF2.5 was localized to the cell wall. The overexpression of AtPDF2.5 significantly enhanced Cd tolerance and accumulation in A. thaliana and its heterologous overexpression in rice increased Cd accumulation; however, the functional disruption of AtPDF2.5 decreased Cd tolerance and accumulation. Physiological analysis suggested that AtPDF2.5 promoted Cd efflux from the protoplast and its subsequent accumulation in the cell wall. These data suggest that AtPDF2.5 promotes cytoplasmic Cd efflux via chelation, thereby enhancing Cd detoxification and apoplastic accumulation.     

The crystal structure of mitochondrial (Type 1A) peptide deformylase provides clear guidelines for the design of inhibitors specific for the bacterial forms

Peptide deformylase (PDF) inhibitors have a strong potential to be used as a new class of antibiotics. However, recent studies have shown that the mitochondria of most eukaryotes, including humans, contain an essential PDF, PDF1A. The crystal structure of the Arabidopsis thaliana PDF1A (AtPDF1A), considered representative of PDF1As in general, has been determined. This structure displays several similarities to that of known bacterial PDFs. AtPDF1A behaves as a dimer, with the C-terminal residues responsible for linking the two subunits. This arrangement is similar to that of Leptospira interrogans PDF, the only other dimeric PDF identified to date. AtPDF1A is the first PDF for which zinc has been identified as the catalytic ion. However, the zinc binding pocket does not differ from the binding pockets of PDFs with iron rather than zinc. The crystal structure of AtPDF1A in complex with a substrate analog revealed that the substrate binding pocket of PDF1A displays strong modifications. The S1' binding pocket is significantly narrower, due to the creation of a floor from residues present in all PDF1As but not in bacterial PDFs. A true S3' pocket is created by the residues of a helical CD-loop, which is very long in PDF1As. Finally, these modified substrate binding pockets modify the position of the substrate in the active site. These differences provide guidelines for the design of bacterial PDF inhibitors that will not target mitochondrial PDFs.     

The Arabidopsis kinase-associated protein phosphatase KAPP,interacting with protein kinases SnRK2.2/2.3/2.6, negatively regulates abscisic acid signaling

Plant Molecular Biology - The kinase-associated protein phosphatase, KAPP, is negatively involved in abscisic acid (ABA) signaling. KAPP interacts physically with SnRK2.2, SnRK2.3 and SnRK2.6, and...     

大棚瓠瓜CO2加富的生理生态效应

春季对大棚瓠瓜CO2,可促进植株的生长发育,株高,茎粗增幅分别达到3．90％－19．48％和11．58％－27．37％,叶片厚度及叶面积也分别增加38．46％－69．23％和26．09％－49．38％;第一雌花着生节位平均降低2．6－4．0节,平均单果重增加4．05％－19．62％,产量 提高8．65％－19．47％,在1000μmol.mol^-1范围内,CO2浓度每增加100μmol.mol^-1,单果重和产量分别增加31．97g和68．39kg.667m^-2,第一雌花着生节位降低0．35节,在1000μmol.mol^-1浓度下,瓠瓜光合速率和羧化速率均达最高值,春季大棚瓠瓜CO2适宜施用浓度为1000μmol.mol^-1左右。     

The crystal structure of plant sulfite oxidase provides insights into sulfite oxidation in plants and animals

The molybdenum cofactor (Moco) containing sulfite oxidase (SO) from Arabidopsis thaliana has recently been identified and biochemically characterized. The enzyme is found in peroxisomes and believed to detoxify excess sulfite that is produced during sulfur assimilation, or due to air pollution. Plant SO (PSO) is homodimeric and homologous to animal SO, but contains only a single Moco domain without an additional redox center. Here, we present the first crystal structure of a plant Moco enzyme, the apo-state of Arabidopsis SO at 2.6 A resolution. The overall fold and coordination of the Moco are similar to chicken SO (CSO). Comparisons of conserved surface residues and the charge distribution in PSO and CSO reveal major differences near the entrance to both active sites reflecting different electron acceptors. Arg374 has been identified as an important substrate binding residue due to its conformational change when compared to the sulfate bound structure of CSO.     

Acoustic recording as a non‐invasive method to detect larval infestation of Cosmopolites sordidus

The banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), is a major pest of banana cropping systems, as larvae bore into the corm of banana plants and damage the insertion points of primary roots, leading to plant snapping and toppling. Plant infestation by the banana weevil is assessed only via invasive techniques, such as plant cutting that highlights larval tunnels. We present here a non‐invasive technique based on a bioacoustic sensor with a band‐pass filter to detect larval activity inside banana corm. On the basis of a test under controlled conditions, we observed that the range of larval activity was between 1.4 and 2.6 kHz. Pulses lasted ca. 168 ms and were separated by intervals of 300 ms. The technique enables detection of more than 90% of infested suckers. The use of this technique to understand larval development of banana weevil is discussed.     

大棚瓠瓜CO2加富的生理生态效应

春季对大棚瓠瓜增施CO₂,可促进植株的生长发育.株高、茎粗增幅分别达到3.90%～19.48%和11.58%～27.37%,叶片厚度及叶面积也分别增加38.46%～69.23%和26.09%～49.38%;第一雌花着生节位平均降低2.6～4.0节.平均单果重增加4.05%～19.62%,产量提高8.65%～19.47%.在1000μmol·mol^-1范围内,CO₂浓度每增加100μmol·mol^-1,单果重和产量分别增加31.97g和68.39kg·667m^-2;第一雌花着生节位降低0.35节.在1000μmol·mol^-1浓度下,瓤瓜光合速率和羧化速率均达最高值.春季大棚瓠瓜CO₂适宜施用浓度为1000μmol·mol^-1左右.     

A role for a menthone reductase in resistance against microbial pathogens in plants

Plants elaborate a vast array of enzymes that synthesize defensive secondary metabolites in response to pathogen attack. Here, we isolated the pathogen-responsive CaMNR1 [menthone: (+)-(3S)-neomenthol reductase] gene, a member of the short-chain dehydrogenase/reductase (SDR) superfamily, from pepper (Capsicum annuum) plants. Gas chromatography-mass spectrometry analysis revealed that purified CaMNR1 and its ortholog AtSDR1 from Arabidopsis (Arabidopsis thaliana) catalyze a menthone reduction with reduced nicotinamide adenine dinucleotide phosphate as a cofactor to produce neomenthol with antimicrobial activity. CaMNR1 and AtSDR1 also possess a significant catalytic activity for neomenthol oxidation. We examined the cellular function of the CaMNR1 gene by virus-induced gene silencing and ectopic overexpression in pepper and Arabidopsis plants, respectively. CaMNR1-silenced pepper plants were significantly more susceptible to Xanthomonas campestris pv vesicatoria and Colletotrichum coccodes infection and expressed lower levels of salicylic acid-responsive CaBPR1 and CaPR10 and jasmonic acid-responsive CaDEF1. CaMNR1-overexpressing Arabidopsis plants exhibited enhanced resistance to the hemibiotrophic pathogen Pseudomonas syringae pv tomato DC3000 and the biotrophic pathogen Hyaloperonospora parasitica isolate Noco2, accompanied by the induction of AtPR1 and AtPDF1.2. In contrast, mutation in the CaMNR1 ortholog AtSDR1 significantly enhanced susceptibility to both pathogens. Together, these results indicate that the novel menthone reductase gene CaMNR1 and its ortholog AtSDR1 positively regulate plant defenses against a broad spectrum of pathogens.     

An oxygenase inhibitor study in Solanum lycopersicum combined with metabolite profiling analysis revealed a potent peroxygenase inactivator

Plant genomes contain a vast number of oxygenase genes, but only very few have been functionally characterized. To devise an alternative method for the detection of novel oxygenase-catalysed reactions the effects of the cytochrome P450 oxygenase inhibitors 1-aminobenzotriazole (ABT) and tetcyclacis (TET) have been examined by metabolite profiling analysis in tomato fruit (Solanum lycopersicum). Treatment with TET resulted in significant increases in the levels of certain flavonoids, whereas ABT strongly inhibited their formation during fruit ripening. Injections of buffered solutions of ABT into tomato fruits led rather to an accumulation of 9,12,13-trihydroxy-10(E)-octadecenoic acid probably due to retarded metabolism of the hydroxylated acid, while TET completely repressed its formation. Peroxygenase, a hydroperoxide-dependent hydroxylase involved in the formation of the trihydroxy fatty acid, is strongly inhibited by TET (IC(50) 2.6 μM) as was demonstrated by studies with the recombinant tomato enzyme expressed in yeast. The data show that ABT and TET affect oxygenases differently in tomato fruit and reveal that these enzymes catalyse distinct reactions in different metabolic pathways, among which C(18)-trihydroxy fatty acid and flavonoid metabolism involve novel oxygenase-catalysed reactions. The method is suitable to identify potential substrates and products of ripening-related, putative oxygenases and can support functional analyses of recombinant enzymes.     

Wickens, G.E. Economic botany: principles and practices

This book is a compendium of information on plants (and somemicro-organisms) that are, or could be, useful to humans. Someidea of its vast scope can be gained from the list of chapterheadings: Plant collecting, taxonomy and nomenclature; Environmentalconsiderations; Plant conservation; Ecophysiology and allieddisciplines; Plant breeding and propagation;     

Response of Vicia faba to short-term uranium exposure: chelating and antioxidant system changes in roots

Journal of Plant Research - Uranium (U) phytotoxicity is an inherently difficult problem in the phytoremediation of U-contaminated environments. Plant chelating and antioxidant systems play an...     

Effect of Exogenously Applied 24-Epibrassinolide and Brassinazole on Xylogenesis and Microdistribution of Cell Wall Polymers in Leucaena leucocephala (Lam) De Wit

Journal of Plant Growth Regulation - Plant growth regulators play a key role in cell wall structure and chemistry of woody plants. Understanding of these regulatory signals is important in advanced...     

Correction to: Ionomic variation in leaves of 819 plant species growing in the botanical garden of Hokkaido University,Japan

Journal of Plant Research - Ionomics is the measurement of total metal, metalloid, and nonmetal accumulation in living organisms. Plant ionomics has been applied to various types of research in the...     

Hemicellulose modification promotes cadmium hyperaccumulation by decreasing its retention on roots in Sedum alfredii

Plant and Soil - Plant growth in the Arctic is often nutrient limited due to temperature constraints on decomposition and low atmospheric input of nitrogen (N). Local hotspots of nutrient...     

Phenotypic characterization of the murine Nkx2.6 homeobox gene by gene targeting

The NK-2 homeobox genes have been shown to play critical roles in the development of specific organs and tissues. Nkx2.6 is a member of the NK-2 homeobox gene family and is most closely related to the Drosophila tinman gene. Nkx2.6 is expressed in the caudal pharyngeal pouches, the caudal heart progenitors, the sinus venosus, and the outflow tract of the heart and in a short segment of the gut at early stages of embryogenesis. To investigate the function of Nkx2.6 in vivo, we generated mice with null mutations of Nkx2.6 by the gene targeting technique. Homozygous Nkx2.6 mutant mice were viable and fertile. There were no obvious abnormalities in the caudal pharyngeal pouch derivatives (the thymus, parathyroid glands, and thyroid gland), heart, and gut. Expression of Nkx2.6 overlaps that of Nkx2.5 in the pharynx and heart and that of Nkx2.3 in the pharynx. Interestingly, in mutant embryos homozygous for Nkx2.6, Nkx2.5 expression extended to the lateral side of the pharynx, suggesting a compensatory function of Nkx2.5 in the mutant pharyngeal pouches.     

Comparing water-related plant functional traits among dominant grasses of the Colorado Plateau: Implications for drought resistance

Plant and Soil - Water is the primary limiting factor for plants in drylands, which are projected to become even drier with climate change. Plant functional traits related to water influences...     

AFD-Net: Apple Foliar Disease multi classification using deep learning on plant pathology dataset

Plant and Soil - Plant diseases significantly affect the crop, so their identification is very important. Correct identification of these diseases is crucial for establishing a good disease control...