In Vitro Acquisition of Specific Small Interfering RNAs Inhibits the Expression of Some Target Genes in the Plant Ectoparasite Xiphinema index

Xiphinema index is an important plant parasitic nematode that induces direct damages and specifically transmits the Grapevine fanleaf virus, which is particularly harmful for grapevines. Genomic resources of this nematode species are still limited and no functional gene validation technology is available. RNA interference (RNAi) is a powerful technology to study gene function and here we describe the application of RNAi on several genes in X. index. Soaking the nematodes for 48 h in a suspension containing specific small interfering RNAs resulted in a partial inhibition of the accumulation of some targeted mRNA. However, low reproducible silencing efficiency was observed which could arise from X. index silencing pathway deficiencies. Indeed, essential accustomed proteins for these pathways were not found in the X. index proteome predicted from transcriptomic data. The most reproducible silencing effect was obtained when targeting the piccolo gene potentially involved in endo-exocytosis of synaptic molecules. This represents the first report of gene silencing in a nematode belonging to the Longidoridae family

Genome Expression Dynamics Reveal the Parasitism Regulatory Landscape of the Root-Knot Nematode Meloidogyne incognita and a Promoter Motif Associated with Effector Genes.

Root-knot nematodes (genus Meloidogyne) are the major contributor to crop losses caused by nematodes. These nematodes secrete effector proteins into the plant, derived from two sets of pharyngeal gland cells, to manipulate host physiology and immunity. Successful completion of the life cycle, involving successive molts from egg to adult, covers morphologically and functionally distinct stages and will require precise control of gene expression, including effector genes. The details of how root-knot nematodes regulate transcription remain sparse. Here, we report a life stage-specific transcriptome of Meloidogyne incognita. Combined with an available annotated genome, we explore the spatio-temporal regulation of gene expression. We reveal gene expression clusters and predicted functions that accompany the major developmental transitions. Focusing on effectors, we identify a putative cis-regulatory motif associated with expression in the dorsal glands, providing an insight into effector regulation. We combine the presence of this motif with several other criteria to predict a novel set of putative dorsal gland effectors. Finally, we show this motif, and thereby its utility, is broadly conserved across the Meloidogyne genus, and we name it Mel-DOG. Taken together, we provide the first genome-wide analysis of spatio-temporal gene expression in a root-knot nematode and identify a new set of candidate effector genes that will guide future functional analyses

As traduções de Le Fanatisme ou Mahomet le Prophète na cena e na página: um caso de voltairomania nas últimas décadas do século XVIII português

info:eu-repo/semantics/publishedVersio

Computationally Efficient Symbol-Level Precoding Communications Demonstrator

We present a precoded multi-user communication test-bed to demonstrate forward link interference mitigation techniques in a multi-beam satellite system scenario which will enable a full frequency reuse scheme. The developed test-bed provides an end-to-end precoding demonstration, which includes a transmitter, a multi-beam satellite channel emulator and user receivers. Each of these parts can be reconfigured accordingly to the desired test scenario. Precoded communications allow full frequency reuse in multiple-input multiple-output (MIMO) channel environments, where several coordinated antennas simultaneously transmit to a number of independent receivers. The developed real-time transmission test-bed assist in demonstrating, designing and benchmarking of the new Symbol-Level Precoding (SLP) techniques, where the data information is used, along with the channel state information, in order to exploit the multi-user interference and transform it into useful power at the receiver side. The demonstrated SLP techniques are designed in order to be computationally efficient, and can be generalized to others multi-channel interference scenarios

Protein accumulation in leaves and roots associated with improved drought tolerance in creeping bentgrass expressing an ipt gene for cytokinin synthesis

Cytokinins (CKs) may be involved in the regulation of plant adaptation to drought stress. The objectives of the study were to identify proteomic changes in leaves and roots in relation to improved drought tolerance in transgenic creeping bentgrass (Agrostis stolonifera) containing a senescence-activated promoter (SAG12) and the isopentyl transferase (ipt) transgene that increases endogenous CK content. Leaves of SAG12-ipt bentgrass exhibited less severe senescence under water stress, as demonstrated by maintaining lower electrolyte leakage and lipid peroxidation, and higher photochemical efficiency (Fv/Fm), compared with the null transformant (NT) plants. SAG12-ipt plants had higher root/shoot ratios and lower lipid peroxidation in leaves under water stress than the NT plants. The suppression of drought-induced leaf senescence and root dieback in the transgenic plants was associated with the maintenance of greater antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase). The SAG12-ipt and NT plants exhibited differential protein expression patterns under well-watered and drought conditions in both leaves and roots. Under equivalent leaf water deficit (47% relative water content), SAG12-ipt plants maintained higher abundance of proteins involved in (i) energy production within both photosynthesis and respiration [ribulose 1,5-bisphosphate carboxylase (RuBisCO) and glyceraldehyde phosphate dehydrogenase (GAPDH)]; (ii) amino acid synthesis (methionine and glutamine); (iii) protein synthesis and destination [chloroplastic elongation factor (EF-Tu) and protein disulphide isomerases (PDIs)]; and (iv) antioxidant defence system (catalase and peroxidase) than the NT plants. These results suggest that increased endogenous CKs under drought stress may directly or indirectly regulate protein abundance and enzymatic activities involved in the above-mentioned metabolic processes, thereby enhancing plant drought tolerance

Function of Arabidopsis hexokinase-like1 as a negative regulator of plant growth

A recent analysis of the hexokinase (HXK) gene family from Arabidopsis revealed that three hexokinase-like (HKL) proteins lack catalytic activity, but share about 50% identity with the primary glucose (glc) sensor/transducer protein AtHXK1. Since the AtHKL1 protein is predicted to bind glc, although with a relatively decreased affinity, a reverse genetics approach was used to test whether HKL1 might have a related regulatory function in plant growth. By comparing phenotypes of an HKL1 mutant (hkl1-1), an HXK1 mutant (gin2-1), and transgenic lines that overexpress HKL1 in either wild-type or gin2-1 genetic backgrounds, it is shown that HKL1 is a negative effector of plant growth. Interestingly, phenotypes of HKL1 overexpression lines are generally very similar to those of gin2-1. These are quantified, in part, as reduced seedling sensitivity to high glc concentrations and reduced seedling sensitivity to auxin-induced lateral root formation. However, commonly recognized targets of glc signalling are not apparently altered in any of the HKL1 mutant or transgenic lines. In fact, most, but not all, of the observed phenotypes associated with HKL1 overexpression occur independently of the presence of HXK1 protein. The data indicate that HKL1 mediates cross-talk between glc and other plant hormone response pathways. It is also considered Whether a possibly decreased glc binding affinity of HKL1 could possibly be a feedback mechanism to limit plant growth in the presence of excessive carbohydrate availability is further considered

The GCR2 Gene Family Is Not Required for ABA Control of Seed Germination and Early Seedling Development in Arabidopsis

BACKGROUND: The plant hormone abscisic acid (ABA) regulates diverse processes of plant growth and development. It has recently been proposed that GCR2 functions as a G-protein-coupled receptor (GPCR) for ABA. However, the structural relationships and functionality of GCR2 have been challenged by several independent studies. A central question in this controversy is whether gcr2 mutants are insensitive to ABA, because gcr2 mutants were shown to display reduced sensitivity to ABA under one experimental condition (e.g. 22 degrees C, continuous white light with 150 micromol m(-2) s(-1)) but were shown to display wild-type sensitivity under another slightly different condition (e.g. 23 degrees C, 14/10 hr photoperiod with 120 micromol m(-2) s(-1)). It has been hypothesized that gcr2 appears only weakly insensitive to ABA because two other GCR2-like genes in Arabidopsis, GCL1 and GCL2, compensate for the loss of function of GCR2. PRINCIPAL FINDINGS: In order to test this hypothesis, we isolated a putative loss-of-function allele of GCL2, and then generated all possible combinations of mutations in each member of the GCR2 gene family. We found that all double mutants, including gcr2 gcl1, gcr2 gcl2, gcl1 gcl2, as well as the gcr2 gcl1 gcl2 triple mutant displayed wild-type sensitivity to ABA in seed germination and early seedling development assays, demonstrating that the GCR2 gene family is not required for ABA responses in these processes. CONCLUSION: These results provide compelling genetic evidence that GCR2 is unlikely to act as a receptor for ABA in the context of either seed germination or early seedling development

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes.

Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus, representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus, respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum

Gene expression analysis in cadmium-stressed roots of a low cadmium-accumulating solanaceous plant, Solanum torvum

Solanum torvum Sw. cv. Torubamubiga (TB) is a low cadmium (Cd)-accumulating plant. To elucidate the molecular mechanisms of the Cd acclimation process in TB roots, transcriptional regulation was analysed in response to mild Cd treatment: 0.1 μM CdCl2 in hydroponic solution. A unigene set consisting of 6296 unigene sequences was constructed from 18 816 TB cDNAs. The distribution of functional categories was similar to tomato, while 330 unigenes were suggested to be TB specific. For expression profiling, the SuperSAGE method was adapted for use with Illumina sequencing technology. Expression tag libraries were constructed from Cd-treated (for 3 h, 1 d, and 3 d) and untreated roots, and 34 269 species of independent tags were collected. Moreover, 6237 tags were ascribed to the TB or eggplant (aubergine) unigene sequences. Time-course changes were examined, and 2049 up- and 2022 down-regulated tags were identified. Although no tags annotated to metal transporter genes were significantly regulated, a tag annotated to AtFRD3, a xylem-loading citrate transporter, was down-regulated. In addition to induction of heavy metal chaperone proteins, antioxidative and sulphur-assimilating enzymes were induced, confirming that oxidative stress developed even using a mild Cd concentration. Rapid repression of dehydration-related transcription factors and aquaporin isoforms suggests that dehydration stress is a potential constituent of Cd-induced biochemical impediments. These transcriptional changes were also confirmed by real-time reverse transcription-PCR. Further additions of TB unigene sequences and functional analysis of the regulated tags will reveal the molecular basis of the Cd acclimation process, including the low Cd-accumulating characteristics of TB

Assessment of biotransfer and bioaccumulation of cadmium, lead and zinc from fly ash amended soil in mustard-aphid-beetle food chain.

The present study investigates the extent of biotransfer and bioaccumulation of cadmium (Cd), lead (Pb) and zinc (Zn) from fly ash amended soil in mustard (Brassica juncea)-aphid (Lipaphis erysimi)-beetle (Coccinella septempunctata) food chain and its subsequent implications for the beetle. The soil was amended with fly ash at the rates of 0, 5, 10, 20 and 40% (w/w). Our results showed that the uptake of Cd, Pb and Zn from soil to mustard root increased with the increase in fly ash application rates, but their root to shoot translocation was relatively restricted. Increase in chlorophyll content and dry mass of mustard plant on treatments ≥20% even at elevated accumulation of Cd (1.67mgkg(-1)), Pb (18.25mgkg(-1)) and Zn (74.45mgkg(-1) dry weight) in its shoot showed relatively higher tolerance of selected mustard cultivar to heavy metal stress. The transfer coefficient (TC(1)) of Cd from mustard shoot to aphid was always >1, indicating that Cd biomagnified in aphids at second trophic level. But, there was no biomagnification of Cd in adult beetles at third trophic level. Zinc accumulation was 2.06 to 2.40 times more in aphids than their corresponding host shoots and 1.26-1.35 times more in adult beetles than their prey (aphids) on which they fed. Lead was only metal whose TC was 0.05) biomass and predation rate of predatory beetles indicated that all levels of soil amendments with fly ash did not have any lethal or sub-lethal effects on beetles