Differential Behavior of Young Eucalyptus Clones in Response to Nitrogen Supply

Eucalyptus requires large amounts of nitrogen (N); however, it responds in diverse manners to the application of this nutrient. The aim of this study was to evaluate the differential performance in growth, mineral nutrition, and gas exchanges of N-fertilized Eucalyptus clones. The treatments consisted of two Eucalyptus clones (VM-01 and I-144) and six N application rates (0, 0.74, 2.93, 4.39, 5.85, and 8 mmol L-1 NH4NO3) arranged in a randomized complete block design with five replications. VM-01 had greater plant height and greater height/collar diameter ratio, as well as higher leaf concentrations of all macronutrients and of Cu, Fe, Mo, and Zn. In terms of total and root dry matter production, root/shoot ratio, and collar diameter, as well as stomatal conductance and transpiration, I-144 performed better. The performance of the clones was clearly differentiated, and the growth of I-144, despite lower leaf N concentration, was in general better than VM-01.

SPATIAL DEPENDENCE OF ELECTRICAL CONDUCTIVITY AND CHEMICAL PROPERTIES OF THE SOIL BY ELECTROMAGNETIC INDUCTION

Brazilian soils have natural high chemical variability; thus, apparent electrical conductivity (ECa) can assist interpretation of crop yield variations. We aimed to select soil chemical properties with the best linear and spatial correlations to explain ECa variation in the soil using a Profiler sensor (EMP-400). The study was carried out in Sidrolândia, MS, Brazil. We analyzed the following variables: electrical conductivity - EC (2, 7, and 15 kHz), organic matter, available K, base saturation, and cation exchange capacity (CEC). Soil ECa was measured with the aid of an all-terrain vehicle, which crossed the entire area in strips spaced at 0.45 m. Soil samples were collected at the 0-20 cm depth with a total of 36 samples within about 70 ha. Classical descriptive analysis was applied to each property via SAS software, and GS+ for spatial dependence analysis. The equipment was able to simultaneously detect ECa at the different frequencies. It was also possible to establish site-specific management zones through analysis of correlation with chemical properties. We observed that CEC was the property that had the best correlation with ECa at 15 kHz.

New wheat genotypes tolerant to aluminum toxicity obtained by mutation induction

Seed from the sensitive wheat (Triticum aestivumL.) cultivar Anahuac was treated to gamma-ray irradiation and eleven Al3+ tolerant mutants selected. The objective was to compare these mutants to the original Anahuac and to the tolerant wheat cultivars IAC-24 and IAC-60 from 1994 to 1996 in acid (Capão Bonito) and limed (Monte Alegre do Sul) soil field trials, in the State of São Paulo, Brazil. Grain yield and agronomic characteristics were analyzed. All the mutant lines yielded higher than the sensitive Anahuac cultivar in the acid soils of Capão Bonito. Under limed soil conditions, 10 mutants had a similar yield to the original sensitive cultivar and one a lower yield. The majority of the mutants were similar in yield to the tolerant cultivars IAC-24 and IAC-60 under both conditions. Some of the mutants showed altered agronomic characteristics, but these alterations did not generally influence the grain yield. The results indicated that tolerant lines with good characteristics may be obtained from a susceptible cultivar by mutation induction, thus allowing cropping under conditions where Al3 + is a limiting factor.

Differential vegetative and reproductive performances among fifteen guinea grass hybrids

The main scope of this work was to detect (Panicum maximum Jacq.) genotype differences as to morphoagronomic and seed quality indices, and to establish character correlations useful for determining vegetative and reproductive trends. Besides the flowering cycle, eight phenological and two seed quality traits were scored in a greenhouse randomized complete block experiment, as follows: plant height (PH), reproductive tiller number/overall tiller number (RTN/OTN), panicle number/reproductive tillers (PN/RT), leaf length (LL), leaf width (LW), panicle length (PL), fresh weight (FW), dry weight (DW), number of seeds/g (NS/G) and seed sample physical purity (SPP). Very-early and early-flowering hybrids consistently showed the highest correlation values among flowering cycle and RTN/OTN (r = -0.59**), PN/RT (r = -0.48**), NS/G (r = -0.88**) and SPP (r = -0.80**) (reproductive parameters) while intermediate and late-flowering hybrids presented the highest values for LL (r = 0.53**), LW (r = 0.60**), PL (r = 0.77**), FW (r = 0.78**) and DW (r = 0.85**) (vegetative traits). The implications of these results for plant breeding and forage management purposes are discussed.

Induction of systemic resistance in tomato by the autochthonous phylloplane resident Bacillus cereus

The objective of this work was to verify if the induced resistance mechanism is responsible for the capacity of a phylloplane resident bacteria (Bacillus cereus), isolated from healthy tomato plants, to control several diseases of this crop. A strain of Pseudomonas syringae pv. tomato was used as the challenging pathogen. The absence of direct antibiosis of the antagonist against the pathogen, the significant increase in peroxidases activity in tomato plants exposed to the antagonist and then inoculated with the challenging pathogen, as well as the character of the protection, are evidences wich suggest that biocontrol efficiency presented by the antagonist in previous works might be due to induced systemic resistance (ISR).

Differential gene expression, induced by salicylic acid and Fusarium oxysporum f. sp. lycopersici infection, in tomato

The objective of this work was to determine the transcript profile of tomato plants (Lycopersicon esculentum Mill.), during Fusarium oxysporum f. sp. lycopersici infection and after foliar application of salicylic acid. The suppression subtractive hybridization (SSH) technique was used to generate a cDNA library enriched for transcripts differentially expressed. A total of 307 clones was identified in two subtractive libraries, which allowed the isolation of several defense-related genes that play roles in different mechanisms of plant resistance to phytopathogens. Genes with unknown roles were also isolated from the two libraries, which indicates the possibility of identifying new genes not yet reported in studies of stress/defense response. The SSH technique is effective for identification of resistance genes activated by salicylic acid and F. oxysporum f. sp. lycopersici infection. Not only the application of this technique enables a cost effective isolation of differentially expressed sequences, but also it allows the identification of novel sequences in tomato from a relative small number of sequences.

Low-P tolerance mechanisms and differential gene expression in contrasting wheat genotypes

The objectives of this study were to determine low-P tolerance mechanisms in contrasting wheat genotypes and to evaluate the association of these mechanisms to differential gene expression. Wheat seedlings of cultivars Toropi (tolerant to low-P availability) and Anahuac (sensitive) were evaluated. Seedlings were hydroponically grown in the absence or presence of P (1.0 mmol L-1) during three different time periods: 24, 120 and 240 hours. Free phosphate (Pi) and total P contents were measured in shoots and roots. The experiment's design was in randomized blocks with three replicates, each formed by ten plants. The relative expression of genes encoding the malate transporter TaALMT1 and the transcription factor PTF1 was evaluated. Phosphorus starvation beyond ten days increased the expression of TaALMT1 only in 'Toropi'. PTF1's expression was early induced in both genotypes under P starvation, but remained significant after ten days only in 'Toropi'. Shoot Pi concentration in 'Toropi' was independent from P availability; under starvation, 'Toropi' favored the maintenance of shoot Pi concentration. The low-P tolerance of Toropi cultivar at initial growth stages is mainly due to its ability to maintain constant the Pi shoot level.

Induction of transgenic hairy roots in soybean genotypes by Agrobacterium rhizogenes‑mediated transformation

The objective of this work was to perform the screening of soybean genotypes as to their ability to respond to the induction of hairy roots by Agrobacterium rhizogenes‑mediated transformation. Four Brazilian soybean cultivars (BRSMG 68 Vencedora, BRS 137, Embrapa 48, and MG/BR 46 Conquista) and two North American ones adapted to Brazilian cropping conditions (Bragg and IAS‑5) were screened for their capacity to respond to A. rhizogenes in protocols for in vitro hairy root culture and ex vitro composite plant production. Four‑day‑old seedlings with uniform size were injected with A. rhizogenes harboring the plasmid p35S‑GFP. Seedlings expressing green fluorescent protein (GFP) in at least one hairy root were used to determine the transformation frequency. Using an axenic in vitro protocol, excised cotyledons from four‑day‑old seedlings were infected with A. rhizogenes harboring the pCAMBIA1301 plasmid, containing the gusA reporter gene. The transformation frequency and the number of days for hairy root emergence after bacterial infection (DAI) were evaluated. The transformation frequency and DAI varied according to the genotype. Cultivars MG/BR 46 Conquista and BRSMG 68 Vencedora are more susceptible to A. rhizogenes and can be recommended for transformation experiments.

Induction of somatic embryogenesis in immature seeds of guavatree cv. Paluma

The biotechnological techniques may help solve many problems of guava culture, such as the high perishability of fruits. Somatic embryogenesis can generate highly multiplicative cell cultures and with high regenerative potential, serving as basis for genetic transformation. The aim of this work was to obtain somatic embryogenesis of guava (Psidium guajava L.) cv. Paluma. Immature seeds were used, and they were inoculated in MS environment containing 400 mg L-1 of L-glutamine, 100 mg L-1 myo-inositol, 60 g L-1 sucrose, 100 mg L-1 ascorbic acid and supplemented with different types and concentrations of growth regulators. Embryogenic callus appeared after 37 days of culture in an environment containing 1.0 mg L-1 2.4-D + 2.0 mg L-1 2-ip, in 7% of the explants. After 65 days of culture, the treatment containing 0.5 mg L-1 CPA showed 20% of explants with direct embryos, while the treatment with 1 mg L-1 had 14% of explants with direct embryos and 7% of explants with embryogenic callus. In 66.6% of embryos regenerated with 0.5 mg L¹ CPA there was the formation of secondary embryos. The use of IASP and BAP, aiming embryogenesis proliferation, led to an increase in the cellular proliferation, but calli apparently lost their embryogenic potential.

Salt stress change chlorophyll fluorescence in mango

This study evaluated the tolerance of mango cultivars 'Haden', 'Palmer', 'Tommy Atkins' and 'Uba' grafted on rootstock 'Imbú' to salt stress using chlorophyll fluorescence. Plants were grown in modified Hoagland solution containing 0, 15, 30, and 45 mmol L-1 NaCl. At 97 days the parameters of the chlorophyll fluorescence (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs)/(Fm')], D = (1- Fv'/Fm') and ETR = (ΦPSII×PPF×0,84×0,5) were determined. At 100 days, the leaf emission and leaf area, toxicity and leaf abscission indexes were determined. In all cultivars evaluated, in different degree, there were decreases in photochemical efficiency of photosystem II, enhanced concentrations from 15 mmol L-1 NaCl. The decreases in the potential quantum yield of photosystem II (Fv/Fm) were 27.9, 18.7, 20.5, and 27.4%, for cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba', respectively, when grown in 45 mmol L-1 NaCl. It was found decreases in leaf emission and mean leaf area in all cultivars from 15 mmol L-1 NaCl. There were increases in leaf toxicity of 33.0, 67.5, 41.6 and 80.8% and in leaf abscission of 71.8, 29.2, 32.5, and 67.9% for the cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba' respectively, when grown in 45 mmol L-1 NaCl. Leaf toxicity and leaf abscission were not observed in 15 mmol L-1 NaCl. The decrease in Fv/Fm ratio were accompanied by decreasing in leaf emission and increased leaf toxicity index, showing, therefore, the potential of chlorophyll fluorescence in the early detection of salt stress in mango tree.

Pyogenic and tuberculous discitis: magnetic resonance imaging findings for differential diagnosis

Spondylodiscitis represents 2%–4% of all bone infections cases. The correct diagnosis and appropriate treatment can prevent complications such as vertebral collapse and spinal cord compression, avoiding surgical procedures. The diagnosis is based on characteristic clinical and radiographic findings and confirmed by blood culture and biopsy of the disc or the vertebra. The present study was developed with Clementino Fraga Filho University Hospital patients with histopathologically and microbiologically confirmed diagnosis of spondylodiscitis, submitted to magnetic resonance imaging of the affected regions. In most cases, pyogenic spondylodiscitis affects the lumbar spine. The following findings are suggestive of the diagnosis: segmental involvement; ill-defined abscesses; early intervertebral disc involvement; homogeneous vertebral bodies and intervertebral discs involvement. Tuberculous spondylodiscitis affects preferentially the thoracic spine. Most suggestive signs include: presence of well-defined and thin-walled abscess; multisegmental, subligamentous involvement; heterogeneous involvement of vertebral bodies; and relative sparing of intervertebral discs. The present pictorial essay is aimed at showing the main magnetic resonance imaging findings of pyogenic and tuberculous discitis.

Hyperechoic breast lesions: anatomopathological correlation and differential sonographic diagnosis

Abstract Hyperechoic lesions are not a frequent finding at breasts ultrasonography, and most of times are associated with benign pathologies that do not require further evaluation. However, some neoplasms such as invasive breast carcinomas and metastases may present with hyperechogenicity. Thus, the knowledge about differential diagnoses and identification of signs of lesion aggressiveness are of great relevance to avoid unnecessary procedures or underdiagnosis, and to support the correct clinical/surgical approach. On the basis of such concepts, the present essay describes and illustrates the main features of hyperechoic lesions at breast ultrasonography in different cases, with anatomopathological correlation.

Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac) of polymer-surfactant complexes and the critical micellar concentration (cmc) of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS) mixtures, solutions containing poly(ethylene oxide)-SDS, poly(vinylpyrrolidone)-SDS and poly(acrylic acid)-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

X-ray fluorescence determination of adsorbed copper on activated charcoal after glycerin complexation

X-This work shows an alternative method to copper determination by X-Ray Fluorescence (XRF). Since copper concentration in natural waters is not enough to reach XRF detection limit, a liquid-solid preconcentration procedure was proposed. Glycerin was used to complex the metal increasing its adsorption on activated charcoal. The solid phase was used to XRF determination. Several parameters were evaluated, such as, the complexation pH, the charcoal adsorption limit and the glycerin concentration. The interferences are lead and bismuth and the sensitivities decreased in the order Cu2+, Bi3+ and Pb2+. The advantages of the method are its simplicity, low cost and low spectral interference.