Characterization of Bean Necrotic Mosaic Virus: A Member of a Novel Evolutionary Lineage within the Genus Tospovirus

Background: Tospoviruses (Genus Tospovirus, Family Bunyaviridae) are phytopathogens responsible for significant worldwide crop losses. They have a tripartite negative and ambisense RNA genome segments, termed S (Small), M (Medium) and L (Large) RNA. The vector-transmission is mediated by thrips in a circulative-propagative manner. For new tospovirus species acceptance, several analyses are needed, e. g., the determination of the viral protein sequences for enlightenment of their evolutionary history. Methodology/Principal Findings: Biological (host range and symptomatology), serological, and molecular (S and M RNA sequencing and evolutionary studies) experiments were performed to characterize and differentiate a new tospovirus species, Bean necrotic mosaic virus (BeNMV), which naturally infects common beans in Brazil. Based upon the results, BeNMV can be classified as a novel species and, together with Soybean vein necrosis-associated virus (SVNaV), they represent members of a new evolutionary lineage within the genus Tospovirus. Conclusion/Significances: Taken together, these evidences suggest that two divergent lineages of tospoviruses are circulating in the American continent and, based on the main clades diversity (American and Eurasian lineages), new tospovirus species related to the BeNMV-SVNaV clade remain to be discovered. This possible greater diversity of tospoviruses may be reflected in a higher number of crops as natural hosts, increasing the economic impact on agriculture. This idea also is supported since BeNMV and SVNaV were discovered naturally infecting atypical hosts (common bean and soybean, respectively), indicating, in this case, a preference for leguminous species. Further studies, for instance a survey focusing on crops, specifically of leguminous plants, may reveal a greater tospovirus diversity not only in the Americas (where both viruses were reported), but throughout the world.

ANTIFUNGAL ACTIVITY OF LECTINS AGAINST YEAST OF VAGINAL SECRETION

Lectins are carbohydrate-binding proteins of non-imune origin. This group of proteins is distributed widely in nature and they have been found in viruses, microorganisms, plants and animals. Lectins of plants have been isolated and characterized according to their chemical, physical-chemical, structural and biological properties. Among their biological activities, we can stress its fungicidal action. It has been previously described the effect of the lectins Dviol, DRL, ConBr and LSL obtained from the seeds of leguminous plants on the growth of yeasts isolated from vaginal secretions. In the present work the experiments were carried out in microtiter plates and the results interpreted by both methods: visual observations and a microplate reader at 530nm. The lectin concentrations varied from 0.5 to 256 mu g/mL, and the inoculum was established between 65-70% of trammitance. All yeast samples isolated from vaginal secretion were evaluated taxonomically, where were observed macroscopic and microscopic characteristics to each species. The LSL lectin did not demonstrate any antifungal activity to any isolate studied. The other lectins DRL, ConBr and DvioL, showed antifungal potential against yeast isolated from vaginal secretion. These findings offering offer a promising field of investigation to develop new therapeutic strategies against vaginal yeast infections, collaborating to improve women's health.

Antifungal activity of lectins against yeast of vaginal secretion

Lectins are carbohydrate-binding proteins of non-imune origin. This group of proteins is distributed widely in nature and they have been found in viruses, microorganisms, plants and animals. Lectins of plants have been isolated and characterized according to their chemical, physical-chemical, structural and biological properties. Among their biological activities, we can stress its fungicidal action. It has been previously described the effect of the lectins Dviol, DRL, ConBr and LSL obtained from the seeds of leguminous plants on the growth of yeasts isolated from vaginal secretions. In the present work the experiments were carried out in microtiter plates and the results interpreted by both methods: visual observations and a microplate reader at 530nm. The lectin concentrations varied from 0.5 to 256µg/mL, and the inoculum was established between 65-70% of trammitance. All yeast samples isolated from vaginal secretion were evaluated taxonomically, where were observed macroscopic and microscopic characteristics to each species. The LSL lectin did not demonstrate any antifungal activity to any isolate studied. The other lectins DRL, ConBr and DvioL, showed antifungal potential against yeast isolated from vaginal secretion. These findings offering offer a promising field of investigation to develop new therapeutic strategies against vaginal yeast infections, collaborating to improve women's health.

Does Brazil need new nuclear power plants?

In October 2008, the Brazilian Government announced plans to invest US$212 billion in the construction of nuclear power plants, totaling a joint capacity of 60,000 MW. Apart from this program, officials had already announced the completion of the construction of the nuclear plant Angra III; the construction of large-scale hydroelectric plans in the Amazon and the implantation of natural gas, biomass and coal thermoelectric plants in other regions throughout the country. Each of these projects has its proponents and its opponents, who bring forth concerns and create heated debates in the specialized forums. In this article, some of these concerns are explained, especially under the perspective of the comparative analysis of costs involved. Under such merit figures, the nuclear option, when compared to hydro plants, combined with conventional thermal and biomass-fueled plants, and even wind, to expand Brazilian power-generation capacity, does not appear as a priority. (C) 2009 Elsevier Ltd. All rights reserved.

Bacterial diversity in rhizosphere soil from Antarctic vascular plants of Admiralty Bay, maritime Antarctica

The Antarctic is a pristine environment that contributes to the maintenance of the global climate equilibrium. The harsh conditions of this habitat are fundamental to selecting those organisms able to survive in such an extreme habitat and able to support the relatively simple ecosystems. The DNA of the microbial community associated with the rhizospheres of Deschampsia antarctica Desv (Poaceae) and Colobanthus quitensis (Kunth) BartI (Caryophyllaceae), the only two native vascular plants that are found in Antarctic ecosystems, was evaluated using a 16S rRNA multiplex 454 pyrosequencing approach. This analysis revealed similar patterns of bacterial diversity between the two plant species from different locations, arguing against the hypothesis that there would be differences between the rhizosphere communities of different plants. Furthermore, the phylum distribution presented a peculiar pattern, with a bacterial community structure different from those reported of many other soils. Firmicutes was the most abundant phylum in almost all the analyzed samples, and there were high levels of anaerobic representatives. Also, some phyla that are dominant in most temperate and tropical soils, such as Acidobacteria, were rarely found in the analyzed samples. Analyzing all the sample libraries together, the predominant genera found were Bifidobacterium (phylum Actinobacteria), Arcobacter (phylum Proteobacteria) and Faecalibacterium (phylum Firmicutes). To the best of our knowledge, this is the first major bacterial sequencing effort of this kind of soil, and it revealed more than expected diversity within these rhizospheres of both maritime Antarctica vascular plants in Admiralty Bay, King George Island, which is part of the South Shetlands archipelago. The ISME Journal (2010) 4, 989-1001; doi:10.1038/ismej.2010.35; published online 1 April 2010

Thermoperiod affects the diurnal cycle of nitrate reductase expression and activity in pineapple plants by modulating the endogenous levels of cytokinins

Nitrate reductase (NR, EC 1.6.6.1) activity in higher plants is regulated by a variety of environmental factors and oscillates with a characteristic diurnal rhythm. In this study, we have demonstrated that the diurnal cycle of NR expression and activity in pineapple (Ananas comosus, cv. Smooth Cayenne) can be strongly modified by changes in the day/night temperature regime. Plants grown under constant temperature (28 degrees C light/dark) showed a marked increase in the shoot NR activity (NRA) during the first half of the light period, whereas under thermoperiodic conditions (28 degrees C light/15 degrees C dark) significant elevations in the NRA were detected only in the root tissues at night. Under both conditions, increases in NR transcript levels occurred synchronically about 4 h prior to the corresponding elevation of the NRA. Diurnal analysis of endogenous cytokinins indicated that transitory increases in the levels of zeatin, zeatin riboside and isopentenyladenine riboside coincided with the accumulation of NR transcripts and preceded the rise of NRA in the shoot during the day and in the root at night, suggesting these hormones as mediators of the temperature-induced modifications of the NR cycle. Moreover, these cytokinins also induced NRA in pineapple when applied exogenously. Altogether, these results provide evidence that thermoperiodism can modify the diurnal cycle of NR expression and activity in pineapple both temporally and spatially, possibly by modulating the day/night changes in the cytokinin levels. A potential relationship between the day/night NR cycle and the photosynthetic pathway performed by the pineapple plants (C(3) or CAM) is also discussed.

Nitric Oxide Mediates the Hormonal Control of Crassulacean Acid Metabolism Expression in Young Pineapple Plants

Genotypic, developmental, and environmental factors converge to determine the degree of Crassulacean acid metabolism (CAM) expression. To characterize the signaling events controlling CAM expression in young pineapple (Ananas comosus) plants, this photosynthetic pathway was modulated through manipulations in water availability. Rapid, intense, and completely reversible up-regulation in CAM expression was triggered by water deficit, as indicated by the rise in nocturnal malate accumulation and in the expression and activity of important CAM enzymes. During both up-and down-regulation of CAM, the degree of CAM expression was positively and negatively correlated with the endogenous levels of abscisic acid (ABA) and cytokinins, respectively. When exogenously applied, ABA stimulated and cytokinins repressed the expression of CAM. However, inhibition of water deficit-induced ABA accumulation did not block the up-regulation of CAM, suggesting that a parallel, non-ABA-dependent signaling route was also operating. Moreover, strong evidence revealed that nitric oxide (NO) may fulfill an important role during CAM signaling. Up-regulation of CAM was clearly observed in NO-treated plants, and a conspicuous temporal and spatial correlation was also evident between NO production and CAM expression. Removal of NO from the tissues either by adding NO scavenger or by inhibiting NO production significantly impaired ABA-induced up-regulation of CAM, indicating that NO likely acts as a key downstream component in the ABA-dependent signaling pathway. Finally, tungstate or glutamine inhibition of the NO-generating enzyme nitrate reductase completely blocked NO production during ABA-induced up-regulation of CAM, characterizing this enzyme as responsible for NO synthesis during CAM signaling in pineapple plants.

Leishmanicidal and cholinesterase inhibiting activities of phenolic compounds of Dimorphandra gardneriana and Platymiscium floribundum, native plants from Caatinga biome

Nos últimos anos, o Ministério da Saúde do Brasil e a Organização Mundial da Saúde tem apoiado a investigação de novas tecnologias que possam contribuir para a vigilância, novos tratamentos e controle da leishmaniose visceral no país. Assim, o objetivo deste trabalho foi isolar compostos de plantas do bioma Caatinga, e investigar a toxicidade destes compostos contra as formas promastigotas e amastigotas de Leishmania infantum chagasi, principal parasita responsável pela leishmaniose visceral na América do Sul, e avaliar a sua capacidade para inibir a enzima acetil-colinesterase (AChE). Após a exposição aos compostos em estudo, foram realizados testes utilizando a forma promastigota que expressa luciferase e ELISA in situ para medir a viabilidade das formas promastigotas e amastigota, respectivamente. O ensaio colorimétrico MTT foi realizado para determinar a toxicidade destas substâncias utilizando células monocíticas murina RAW 264.7. Todos os compostos foram testados in vitro para as sua propriedade anti-colinesterásica. Um cumarina, escoparona, foi isolada a partir de hastes de Platymiscium floribundum, e os flavonóides, rutina e quercetina, foram isolados a partir de grãos de Dimorphandra gardneriana. Estes compostos foram purificados, utilizando cromatografia em coluna gel eluída com solventes orgânicos em misturas de polaridade crescente, e identificados por análise espectral. Nos ensaios leishmanicidas, os compostos fenólicos mostraram eficácia contra as formas extracelulares promastigotas, com EC50 para escoporona de 21.4µg/mL e para quercetina e rutina 26 e 30.3µg/mL, respectivamente. Os flavonóides apresentaram resultados comparáveis à droga controle, a anfotericina B, contra as formas amastigotas com EC50 para quercetina e rutina de 10.6 e 43.3µg/mL, respectivamente. Os compostos inibiram a enzima AChE com halos de inibição variando de 0,8 a 0,6cm, indicando um possível mecanismo de ação para a atividade leishmanicida.

PHOSPHITE AS PHOSPHORUS SOURCE TO GRAIN YIELD OF COMMON BEAN PLANTS GROWN IN SOILS UNDER LOW OR ADEQUATE PHOSPHATE AVAILABILITY

The effects of foliar and soil applied phosphite on grain yield in common bean (Phaseolus vulgaris L.) grown in a weathered soil under low and adequate phosphate availability were evaluated. In the first experiment, treatments were composed of a 2 x 7 + 2 factorial scheme, with 2 soil P levels supplied as phosphate (40 e 200 mg P dm(-3) soil), 7 soil P levels supplied as phosphite (0-100 mg P dm(-3) soil), and 2 additional treatments (without P supply in soil, and all P supplied as phosphite). In the second experiment, treatments were composed of a 2 x 3 x 2 factorial scheme, with 2 soil phosphate levels (40 e 200 mg P dm(-3) soil), combined with 3 nutrient sources applied via foliar sprays (potassium phosphite, potassium phosphate, and potassium chloride as a control), and 2 foliar application numbers (single and two application). Additional treatments showed that phosphite is not P source for common bean nutrition. Phosphite supply in soil increased the P content in shoot (at full physiological maturity stage) and grains, but at the same time considerably decreased grain yield, regardless of the soil phosphate availability. Foliar sprays of phosphite decreased grain yield in plants grown under low soil phosphate availability, but no effect was observed in plants grown under adequate soil phosphate availability. In general, foliar sprays of phosphate did not satisfactorily improve grain yield of the common bean plants grown under low soil phosphate availability.

A Novel Stress-Induced Sugarcane Gene Confers Tolerance to Drought, Salt and Oxidative Stress in Transgenic Tobacco Plants

Background: Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. Methodology/Principal Findings: In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. Conclusions/Significance: The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO2 concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.

Further investigating the determination of phosphorus in plants by INAA using bremsstrahlung measurement

Phosphorus is an essential element for plants and animals, playing a fundamental role in the production of biochemical energy. Despite its relevance, phosphorus is not commonly determined by instrumental neutron activation analysis (INAA), because (32)P does not emit gamma-rays in its decay. There are alternative methods for the determination of phosphorus by INAA, such as the use of beta counting or the measurement of bremsstrahlung originated from the high energy beta particle from (32)P. Here the determination of phosphorus in plant materials by measuring the bremsstrahlung production was further investigated, to optimize an analytical protocol for minimizing interferences and overcoming the poor specificity. Eight certified reference materials of plant matrices with phosphorus ranging between 171 and 5,180 mg kg(-1) were irradiated at a thermal neutron flux of 9.5 x 10(12) cm(-2) s(-1) and measured with a HPGe detector at decay times varying from 7 to 60 days. Phosphorus solutions added to a certified reference material at three levels were used for calibration. Counts accumulated in the baseline at four different regions of the gamma-ray spectra were tested for the determination of phosphorus, with better results for the 100 keV region. The Compton scattering contribution in the selected range was discounted using an experimental peak-to-Compton factor and the net areas of all peaks in the spectra with energies higher than 218 keV, i.e. Compton edge above 100 keV. Amongst the interferences investigated, the production of (32)P from sulfur, and the contribution of Compton scattering should be considered for producing good results.

Glyphosate has low toxicity to citrus plants growing in the field

Gravena, R., Filho, R. V., Alves, P. L. C. A., Mazzafera, P. and Gravena, A. R. 2012. Glyphosate has low toxicity to citrus plants growing in the field. Can. J. Plant Sci. 92: 119-127. There has been controversy over whether glyphosate used for weed management in citrus fields causes significant toxicity to citrus plants. Glyphosate may be toxic to non-target plants exposed to accidental application or drift. This work evaluated glyphosate toxicity in plants of Valencia citrus (Citrus sinensis. L. Osbeck) grafted onto 'Rangpur lime' (Citrus limonia L. Osbeck) and citrumelo 'Swingle' (Poncirus trifoliata (L.) Raf x Citrus paradisi Mad) by trunk- or foliar-directed herbicide applications under field conditions. In the first experiment, glyphosate was sprayed at rates of 0, 90, 180, 260, 540, 1080 and 2160 g a.e. ha(-1) directly on the trunk to a height of 5 cm above the grafting region. In the second experiment, glyphosate was sprayed on the plant canopies at rates of 0, 0.036, 0.36, 3.6, 36, 360 and 720 g a.e. ha(-1). There was no visual damage caused by glyphosate applied directly to the trunk, but the plants were affected by glyphosate sprayed directly on the canopies at rates over 360 g a.e. ha(-1). The main symptom was observed in the new shoots formed after the application, indicating an effect on meristems. Little or no effect was observed in mature leaves. Eight days after application the levels of shikimate, total free amino acids and total phenolic compounds were unaffected. All plants affected by glyphosate recovered between 6 and 12 mo after the treatments. Therefore, despite some transient symptoms Valencia citrus grafted onto 'Rangpur lime' and citrumelo 'Swingle' were tolerant to glyphosate.

Genetic transformation of three sweet orange cultivars from explants of adult plants

The difficulty in adult tissue genetic transformation in woody species is still an obstacle to be overcome, including in most sweet orange cultivars of the Brazilian citrus industry. This work reports that, after in vitro culture adjustments, transgenic adventitious buds of 'Hamlin', 'Pra', and 'Valencia' sweet oranges (Citrus sinensis L. Osbeck) were recovered using adult material as explant source, in genetic transformation experiments via Agrobacterium tumefaciens. The transgenic buds were identified by the GUS histochemical analysis and confirmed by PCR analysis, which indicated the presence of an amplified fragment of 817 bp corresponding to the uidA gene sequence. The efficiencies of genetic transformation for 'Hamlin', 'Pra', and 'Valencia' sweet orange cultivars were 2.5, 1.4, and 3.7%, respectively. Media supplemented with auxins and cytokinins during co-culture, and media with high concentrations of cytokinins (3 mg L-1) during transgenic selection led to the transformation and, consequently, the regeneration of adequate number of adventitious buds for the three cultivars. The use of sonication during the explant disinfection was not effective to reduce endophytic contamination and reduced transformation efficiency.

Possible Host Adaptation as an Evolution Factor of Cowpea aphid-borne mosaic virus Deduced by Coat Protein Gene Analysis

Cowpea aphid-borne mosaic virus (CABMV) causes major diseases in cowpea and passion flower plants in Brazil and also in other countries. CABMV has also been isolated from leguminous species including, Cassia hoffmannseggii, Canavalia rosea, Crotalaria juncea and Arachis hypogaea in Brazil. The virus seems to be adapted to two distinct families, the Passifloraceae and Fabaceae. Aiming to identify CABMV and elucidate a possible host adaptation of this virus species, isolates from cowpea, passion flower and C.hoffmannseggii collected in the states of Pernambuco and Rio Grande do Norte were analysed by sequencing the complete coat protein genes. A phylogenetic tree was constructed based on the obtained sequences and those available in public databases. Major Brazilian isolates from passion flower, independently of the geographical distances among them, were grouped in three different clusters. The possible host adaptation was also observed in fabaceous-infecting CABMV Brazilian isolates. These host adaptations possibly occurred independently within Brazil, so all these clusters belong to a bigger Brazilian cluster. Nevertheless, African passion flower or cowpea-infecting isolates formed totally different clusters. These results showed that host adaptation could be one factor for CABMV evolution, although geographical isolation is a stronger factor.

Ecological aspects of the sandfly fauna (Diptera, Psychodidae) in an American cutaneous leishmaniasis endemic area under the influence of hydroelectric plants in Paranapanema river, State of Parana, Brazil

Introduction: An epidemiological study was undertaken to identify determinant factors in the occurrence of American cutaneous leishmaniasis in areas under the influence of hydroelectric plants in Paranapanema river, State of Parana, Brazil. The ecological aspects of the phlebotomine fauna were investigated. Methods: Sandflies were sampled with automatic light traps from February 2004 to June 2006 at 25 sites in the urban and rural areas of Itambaraca, and in Porto Almeida and Sao Joaquim do Pontal. Results: A total of 3,187 sandflies of 15 species were captured. Nyssomyia neivai predominated (34.4%), followed by Pintomyia pessoai (32.6%), Migonemyia migonei (11.6%), Nyssomyia whitmani (8.8%), and Pintomyia fischeri (2.7%), all implicated in the transmission of Leishmania. Males predominated for Ny. neivai, and females for the other vector species, with significant statistical differences (p < 0.001). Nyssomyia neivai, Pi. pessoai, Ny. whitmani, Brumptomyia brumpti, Mg. migonei, and Pi. fischeri presented the highest values for the Standardized Species Abundance Index (SSAI). The highest frequencies and diversities were found in the preserved forest in Porto Almeida, followed by forests with degradation in Sao Joaquim do Pontal and Vila Rural. Conclusions: Sandflies were captured in all localities, with the five vectors predominating. Ny. neivai had its highest frequencies in nearby peridomestic environments and Pi. pessoai in areas of preserved forests. The highest SSAI values of Ny. neivai and Pi. pessoai reflect their wider dispersion and higher frequencies compared with other species, which seems to indicate that these two species may be transmitting leishmaniasis in the area.