Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean

Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean Asian rust, caused by the fungus Phakopsora pachyrhizi, is one of the most serious phytosanitary problems of soybean in Brazil, especially because no cultivars with satisfactory resistance levels as yet exist. The objective of this study was to evaluate the influence of luminosity and of leaf epicuticular wax on the infection of soybean by P. pachyrhizi. The adaxial and abaxial leaflet surfaces of the first trifoliate leaf from cultivar BRS 154, phenological stage V2, were inoculated with a suspension of 105 uredospores/mL. The plants were kept for 24 hours in a humid chamber at temperature of 23 degrees C, in light or dark conditions, using a factorial design. Subsequently, the plants were maintained for 14 days under a 12-hour photoperiod. The disease severity and density were evaluated. For in vitro experiments, in light or dark conditions, the evaluation was done in terms of uredospore germination and appressorium formation. The wax content of adaxial and abaxial leaflets was analyzed quantitatively using chloroform extraction and ultrastructurally using scanning electron microscope. Higher density and severity were observed when the adaxial surface was inoculated, with later incubation of the plants in the dark, with no significant interaction between these factors. Spore germination in the dark (40.7%) was statistically different from spore germination in the light (28.5%). The same effect was observed with appressorium formation, in the dark (24.7%) and in the light (12.8%). The quantity and the ultrastructural aspects of epicuticular wax content did not show differences between the adaxial and abaxial surfaces; nor did they show any effect on infection by Phakopsora pachyrhizi in the soybean cultivar studied.

Influence of soybean phenological stage and leaflets age on infection by Phakopsora pachyrhizi

Influence of soybean phenological stage and leaflets age on infection by Phakopsora pachyrhizi This work was conducted to study the influence of soybean growth stage and leaf age on the infection of Phakopsora pachyrhizi, the soybean rust pathogen. Soybean plants (cv. BRS 154 and BRS 258) at the V(3), R(1) and R(5) growth stages were inoculated with a 1 x 10(5) urediniospores per mL suspension. After a period of 24 hours in dew chambers, all plants were removed from the chambers and placed under greenhouse conditions for 20 days. Mean latent period (PLM) and disease severity were estimated. The susceptibility of trifoliate leaves to soybean rust was estimated on cv. BRS 154 at the growth stage R5. Pathogen inoculation was done at the first four trifoliate leaves. Fifteen days after inoculation, leaflets of each trefoil were evaluated for disease severity, lesion mean size and infection frequency. Plants` growth stage did not influence the PLM. Cultivars BRS 154 and BRS 258 presented PLM of 8 and 9 days, respectively. There was no difference in disease severity at the growth stages V(3) and R(1), but those values were higher than at the R(5) growth stage, 8 days after inoculation. The oldest trefoil showed the highest disease values.

Diversity of endophytic bacteria from Eucalyptus species seeds and colonization of seedlings by Pantoea agglomerans

The diversity and beneficial characteristics of endophytic microorganisms have been studied in several host plants. However, information regal-ding naturally, occurring seed-associated endophytes and vertical transmission among different life-history stages of hosts is limited. Endophytic bacteria were isolated from seeds and seedlings of 10 Eucalyptus species and two hybrids. The results showed that endophytic bacteria, Such as Bacillus, Enterococcus, Paenibacillus and Methylobacterium, are vertically transferred from seeds to seedlings. In addition, the endophytic bacterium Pantoea agglomerans was tagged with the gfp gene, inoculated into seeds and further reisolated from seedlings. These results suggested it novel approach to change the profile of the plants, where the bacterium is a delivery vehicle for desired traits. This is the first report of an endophytic bacterial community residing in Eucalyptus seeds and the transmission of these bacteria from seeds to seedlings. The bacterial species reported ill this work have been described as providing benefits to host plants. Therefore, we Suggest that endophytic bacteria can be transmitted vertically from seeds to seedlings, assuring the support of the bacterial community in the host plant.

Isoflavones and antioxidant capacity of Peruvian and Brazilian lupin cultivars

Seed coats, cotyledons and hypocotyls from six Peruvian (Lupinus mutabilis Sweet) and two Brazilian (Lupinus albus and Lupinus angustifolius) lupin cultivars were assessed regarding their content of isoflavones and antioxidant capacity. Genistein and a genistein derivative were detected in seed coats and cotyledons from Peruvian cultivars. Total isoflavones ranged from 9.8 to 87, 16.1 to 30.8 and 1.3 to 6.1 mg/100 g of sample in fresh weight (expressed as genistein) in seed coat, cotyledon and hypocotyl fractions, respectively, from mutabilis species, whereas no isoflavones were detected in L. angustifolius and L. albus. A significant correlation (r = 0.99) was found between the total isoflavone levels and the antioxidant capacity measured by the 2,2-diphenyl-1-picrylhydrazyl radical-scavenging method in all fractions of Peruvian samples. No condensed tannins were detected in any of the lupin cultivars. The H-6 Andean cultivar is promising for its high isoflavone content and antioxidant capacity. Insights from this study indicate that lupin cultivars of the mutabilis species have similar isoflavone profiles and that isoflavones are more concentrated in the cotyledon seed fraction than in the seed coat or hypocotyl fractions. (C) 2008 Elsevier Inc. All rights reserved.

Effect of Different Cooking Conditions on Phenolic Compounds and Antioxidant Capacity of Some Selected Brazilian Bean (Phaseolus vulgaris L.) Cultivars

The effects of different cooking conditions such as soaking, atmospheric (100 degrees C) or pressure boiling (121 degrees C), and draining of cooking water following thermal treatment on phenolic compounds and the DPPH radical scavenging capacity from two selected Brazilian bean cultivars (black and yellow-brown seed coat color) were investigated using a factorial design (2(3)). Factors that significantly reduced the total phenolic contents and antioxidant capacity in both cultivars were the soaking and draining stage. Independent of cooking temperature, total phenolics and antioxidant capacities were enhanced in treatments without soaking and where cooking water was not discarded, and this was likely linked to an increase of specific phenolic compounds detected by high performance liquid chromatography such as flavonols and free phenolic acids in both cultivars. Cooking of beans either at 100 or 121 degrees C, without a soaking stage and keeping the cooking water, would be recommendable for retaining antioxidant phenolic compounds.

Evaluation of aluminium tolerance in grapevine rootstocks

Aluminum (Al) toxicity is a major worldwide agricultural problem. At low pH, Al speciates into the soluble and phyto-toxic form Al(3+), inhibiting the root growth and affecting plant development. In Brazil, agriculture in acidic soils with elevated concentration of Al has significantly increased in the last decades. Therefore, in order to achieve efficient agriculture practices, the selection of plant cultivars with improved Al resistance has become crucial in this type of soils. In this work we have evaluated the Al resistance of six genotypes of grapevine rootstocks. The grapevine hardwood cuttings were grown in nutrient solution in the absence and presence of 250 and 500 mu M Al at pH 4.2. The phenotypic indexes of relative root growth, fresh and dry root weight, root area, hematoxylin staining profile, and Al content were evaluated for all six genotypes. These phenotypic indexes allowed us to identify the `Kober 5BB`, `Gravesac`, `Paulsen 1103`, and `IAC 766` grapevine rootstocks genotypes as the ones with the highest resistance to Al. Likewise, `IAC 572` and `R110` genotypes were the most Al-sensitive cultivars. We evaluated the root organic acid exudation profile in the most Al-resistant (`Kober 5BB`) and most Al-sensitive (`R110`) in plantlets cultivated in vitro in the absence and presence of 100, 200, and 400 mu M of Al. Among several compounds detected, citrate was the only organic acid related to the Al resistance phenotype observed in the `Kober 5BB` genotype. The high constitutive citrate exudation observed in `Kober 5BB` strongly suggests that exudation of this particular organic acid may impart Al-resistance/a melioration in grapevine.

Functionality of bioactive compounds in Brazilian strawberry (Fragaria x ananassa Duch.) cultivars: Evaluation of hyperglycemia and hypertension potential using in vitro models

Fruits of seven fully ripened strawberry cultivars grown in Brazil (Dover, Camp Dover, Camarosa, Sweet Charlie, Toyonoka, Oso Grande, and Piedade) were evaluated for total phenolics, antioxidant activity based on DPPH radical scavenging assay, and functionality such as inhibition of alpha-amylase, alpha-glucosidase, and angiotensin I-converting enzyme (ACE) relevant for potentially managing hyperglycemia and hypertension. The total phenolics content ranged from 966 to 1571 mu g of gallic acid/g of fruit fresh weight for Toyonoka and Dover, respectively. No correlation was found between total phenolics and antioxidant activity. The major phenolic compounds in aqueous extracts of strawberries were ellagic acid, quercetin, and chlorogenic acid. Strawberries had high alpha-glucosidase inhibitory activity. However, alpha-amylase inhibitory activity was very low in all cultivars. This suggested that strawberries could be considered as a potential dietary source with anti-hyperglycemic potential. The evaluated cultivars had no significant ACE inhibitory activity, reflecting low anti-hypertensive potential.

Non-starch polysaccharide composition of two cultivars of banana (Musa acuminata L.: cvs Mysore and Nanicao)

Fruits represent a rich source of soluble and insoluble fibre, and the pectin is the most common and known soluble fraction from the cell wall solubilization occurring during fruit ripening. Banana fruit, for example, is one of the most consumed fruits in the world, but its non-starch polysaccharide composition is almost unknown. Despite few works have been carried out about the enzymes concerning cell wall loosening focusing banana ripening, there is no knowledge about the composition of the banana cell wall. Moreover, there is no information about the influence of the cultivar in that composition. Nanicao and Mysore cultivars were chosen for this work because of their differential accumulation of both starch during development and amounts of total fibre in the ripe fruit. Nanicao and Mysore had their fibres subfractioned and their composition analysed. Results showed that the cultivars are distinct not only in terms of starch and soluble sugars accumulation, but also in non-starch polysaccharides amounts and composition. Non-starch polysaccharides are similar in total amounts in both banana cultivars (similar to 3.5), but substantially different in the content of CDTA and NaOH-4M soluble fractions and also in the molecular mass distribution of WSP and CDTA. Nanicao has more calcium-linked pectin than Mysore, which in turn is richer in hemicellulose-like polysaccharides. Both cultivars likewise cereals polysaccharides seem to be composed of galacturonans and arabinoxylans.(c) 2007 Elsevier Ltd. All rights reserved.

Rapid detection of resistance to pyrazinamide in Mycobacterium tuberculosis using the resazurin microtitre assay

Objectives: The resazurin microtitre plate assay (REMA) was evaluated to determine the susceptibility of Mycobacterium tuberculosis to pyrazinamide, and was compared with the broth microdilution method (BMM), the absolute concentration method (ACM) and pyrazinamidase (PZase) determination. Methods: Thirty-four M. tuberculosis clinical isolates (26 susceptible and 8 resistant to pyrazinamide) and reference strains M. tuberculosis H37Rv ATCC 27294 and Mycobacterium bovis AN5 were tested. Results: REMA and BMM showed 100% specificity and sensitivity when compared with ACM; BMM, however, demanded more reading time. The PZase determination assay showed 87.50% and 100% sensitivity and specificity, respectively. Conclusions: All tested methods in this preliminary study showed excellent sensitivity and specificity for the determination of pyrazinamide susceptibility of M. tuberculosis, but REMA was faster, low-cost and easy to perform and interpret. Additional studies evaluating REMA for differentiating pyrazinamide-resistant and-susceptible M. tuberculosis should be conducted on an extended panel of clinical isolates.

Dissemination of bla(IMP-1)-carrying integron In86 among Klebsiella pneumoniae isolates harboring a new trimethoprim resistance gene dfr23

The genetic context of the bla(IMP-1) gene was evaluated in 9 Klebsiella pneumoniae isolates recovered from 2 hospitals in Sao Paulo, Brazil. All isolates harbored a copy of In86 carrying bla(Imp-1), aac(6`)-31, and aadAl. Eight strains from the same hospital also carried another class I integron harboring a new trimethoprim resistance gene (dfr23) that was chromosomally embedded. In86 was likely to be in a 30-kb nontransferable plasmid and was flanked upstream by a sequence identical to one identified in an IMP-1-producing Pseudomonas putida isolate. The bla(IMP-1)-carrying integron In86 was recently reported from nonfermentative bacilli isolated in Sao Paulo. These isolates appear to be the Source of this integron now acquired by K. pneumoniae strains from different hospitals in the same city. Metallo-beta-lactamase production is still rare among Enterobacteriaceae isolates in Brazil, but the acquisition of genetic structures carrying these mobile resistance determinants is worrisome and could lead to an increase in the prevalence of these phenotypes of resistance. (C) 2008 Elsevier Inc. All rights reserved.

Sigatoka disease reduces the greenlife of bananas

Sigatoka disease (SD) of bananas is caused by the pathogenic fungus Mycosphaerella musicola Leach. This disease provokes necrotic lesions on leaves and serious infestations can lead to a substantial reduction in the leaf area of infected plants and thus to yield losses. In addition to these effects on yield, SO was found to have an impact on fruit quality, especially because exported bananas ripen prematurely. In the present work, a plantation survey and experiments have been conducted in Guadeloupe (FWI) to assess the effect of this disease on the greenlife of bananas harvested at a constant physiological age, as measured in degree-days (dd). Our results revealed that bananas harvested at 900 dd from plants with high Sigatoka disease severity had normal diameter growth, but a shorter greenlife (GL) than bananas harvested from uninfected plants. These results indicate that SD is directly responsible for the reduction of banana greenlife since the reduction of GL could not be attributed to the harvest of fruits at a more advanced physiological age (dd). Furthermore, a correlation was noted between SO severity and GL The potential physiological mechanisms involved are also discussed. (C) 2008 Elsevier Ltd. All rights reserved.

The roles played by Aspergillus nidulans apoptosis-inducing factor (AIF)-like mitochondrial oxidoreductase (AifA) and NADH-ubiquinone oxidoreductases (NdeA-B and NdiA) in farnesol resistance

Farnesol (FOH) is a nonsterol isoprenold produced by dephosphorylanon of farnesyl pyrophosphate a catabolite of the cholesterol biosynthetic pathway These isoprenoids inhibit proliferation and induce apoptosis Here we show that Aspergillus nidulans MA encoding the apoptosis-Inducing factor (AIF)-like mitochondrial oxidoreductase plays a role in the function of the mitochondrial Complex I Additionally we demonstrated that ndeA B and ndiA encode external and internal alternative NADH dehydrogenases respectively that have a function in FOH resistance When exposed to FOH the Delta aifA and Delta ndeA strains have increased ROS production while Delta ndeB Delta ndeA Delta ndeB and Andul mutant strains showed the same ROS accumulation than in the absence of FOH We observed several compensatory mechanisms affecting the differential survival of these mutants to FOH (C) 2010 Elsevier Inc All rights reserved

Zinc supplementation increases resistance to experimental infection by Trypanosoma cruzi

It is well recognized that zinc is an essential trace element for all organisms, influencing growth and affecting the development and integrity of the immune system. It is also well known that the protective response against Trypanosoma cruzi depends on both innate and acquired immunity and for the control of the parasite load and host survival, the participation of special cells such natural killer (NK), T and B lymphocytes and macrophages are required. So the aims of this study were to evaluate the effects of zinc supplementation on the host`s immune response infected with T cruzi. Our data point in the direction that zinc supplementation triggered enhanced thymocyte and splenocyte proliferation as compared to unsupplied group of animals. It is also important to emphasize that interleukin-12 (IL-12) participates in the resistance to several intracellular pathogens including T cruzi. Our findings demonstrate an enhanced production of IL-12 during the acute phase of infection in zinc-supplied groups. So we conclude that zinc supplementation leads to an effective host`s immune response by up-modulating the host`s immune response, thus contributing in the reduction of blood parasites and the harmful pathogenic effects of the experimental Chagas` disease. (c) 2008 Elsevier B.V. All rights reserved.

Dehydroepiandrosterone increases resistance to experimental infection by Trypanosoma cruzi

Dehydroepiandrosterone (DHEA) enhances immune responses against a wide range of viral, bacterial, and parasitic pathogens. In a previous study, we reported that administration of DHEA significantly decreased the numbers of blood parasites in Trypanosoma cruzi experimental infection. The present study was undertaken to determine the effectiveness of DHEA in reducing the severity of acute phase T cruzi infection of male and female Wistar rats. Animals were treated subcutaneously with 40 mg/kg body weight/day of DHEA. The concentration of nitric oxide (NO) was determined in spleen peritoneal cavity. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were determined in the sera of uninfected and infected animals. DHEA treatment augments NO production for both sexes after in vitro LPS treatment for uninfected animals. Infection triggered enhanced NO levels although not significant. IL-2 and IFN-gamma were detectable in higher concentrations in treated and infected rats of both genders when compared to untreated controls. These data suggest that DHEA may have a potent immunoregulatory function that can affect the course of T cruzi infection. (c) 2008 Elsevier B.V. All rights reserved.

Determinants of beta-lactam resistance in meningitis-causing Enterobacteriaceae in Brazil

This study analyzed resistance determinants in extended-spectrum beta-lactamase (ESBL)-producing enterobacteria and the epidemiology of 11 Escherichia coli isolates obtained from meningitis patients in a region of Brazil from 2000 to 2005. ESBL-encoding genes and their genetic environment were investigated by PCR and sequencing. The gene bla(CTX-M-2) was identified in 3 different enterobacteria (E. coli. Serratia marcescens, and Proteus mirabilis) downstream of the insertion sequence ISCR1 (localized in class 1 integrons), hut not as part of the resistance cassettes region. Multi locus sequence typing (MLST) was used to investigate genetic relationships between the 11 E. coil isolates in this study and strains associated with meningitis in the E. coil MLST database. MLST analysis indicated high genetic diversity among isolates, and no significant genetic relationship was identified with meningitis-causing E. coil in the database. The results in this report reinforce the need to be attentive to meningitis suspected to be due to ESBL-producing enterobacterial isolates, especially where ESBL epidemiology is well known.