Eucalyptus ESTs involved in mechanisms against plant pathogens and environmental stresses

Eucalypt plantation has high economical importance in Brazil; however, it has been attacked by various pathogens under different environmental stress conditions. Disease resistance and survival under unfavorable environmental conditions have revealed that the eucalypt has developed highly efficient defense systems. Here we show the results of the Eucalyptus ESTs Genome Project (FORESTs). Using the expressed sequence tags (ESTs) obtained by the Project, contigs of similar sequences from each cDNA library induced and not induced by stress agents were formed, and cDNA sequences similar to other already known molecules, such as plant-signaling molecules, phytoalexins, lignin biosynthesis pathways, PR-proteins and putative genes corresponding to enzymes involved in the detoxification of reactive oxygen species, were identified. We also present general considerations about the mechanisms of Eucalyptus defense against biotic and abiotic stresses. These data are of extreme importance for future eucalypt breeding programs aimed at developing plants with enhanced resistance against pathogens and environmental stresses.

Nematicidal effect of volatile organic compounds (VOCs) on the plant-parasitic nematode Meloidogyne javanica

Previous studies have demonstrated that volatile organic compounds (VOCs), produced by the yeast Saccharomyces cerevisiae, were able to inhibit the development of phytopathogenic fungi. In this context, the nematicidal potential of the synthetic mixture of VOCs, constituted of alcohols and esters, was evaluated for the control of the root-knot nematode Meloidogyne javanica, which causes losses to crops of high economic value. The fumigation of substrate containing second-stage juveniles with VOCs exhibited nematicidal effect higher than 30% for the lowest concentration tested (33.3 µL g-1 substrate), whereas at 66.6 and 133.3 µL g-1 substrate, the nematode mortality was 100%. The present results stimulate other studies on VOCs for nematode management.

Effect of light intensity and growth substratum on plant development and production of secondary metabolites in Cordia curassavica (Jacq.) Roem. & Schult

Cordia curassavica (Jacq.) Roem. & Schult. (Boraginaceae), also referred to as Cordia verbenacea DC, has been traditionally used for medicinal purposes. This study was driven to verify the behavior of the species in similar conditions to its natural environment, such as high light intensity and sandbank soil, and in conditions of low light intensity and fertilized substratum (dystroferric red nitosoil plus earthworm humus). The growth of the plant, the income of leaf crude extracts and, in the alcoholic extract, the number of substances found in thin layer cromatography and the toxicity of the substratum was observed. The results indicated that the growth of the root biomass, stem and leaves in discharge or lower light intensity was similar, but smaller in sandbank soil than in fertilized soil. The relative income of extracts in ether of petroleum and alcohol was larger in high light intensity and fertilized substratum. The light intensity and the substratum type didn't affect the number of substances detected in the alcoholic extract or the toxicity of this extract. Stains corresponding to the rosmarinic acid were only evidenced in some samples of the alcoholic extract, not allowing the verification of the effect of the treatments about its production.

Effects of global climate changes on geographical distribution patterns of economically important plant species in cerrado

Different climate models, modeling methods and carbon emission scenarios were used in this paper to evaluate the effects of future climate changes on geographical distribution of species of economic and cultural importance across the Cerrado biome. As the results of several studies have shown, there are still many uncertainties associated with these projections, although bioclimatic models are still widely used and effective method to evaluate the consequences for biodiversity of these climate changes. In this article, it was found that 90% of these uncertainties are related to methods of modeling, although, regardless of the uncertainties, the results revealed that the studied species will reduce about 78% of their geographic distribution in Cerrado. For an effective work on the conservation of these species, many studies still need to be carried out, although it is already possible to observe that climate change will have a strong influence on the pattern of distribution of these species.

Does the edge effect influence plant community structure in a tropical dry forest?

Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m) were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.

Thinning effect on plant growth of pruned eucalypt clone

A pruned stand of eucalypt clone underwent five thinning treatments with the removal of different proportion of the planted trees, at different ages: a) 0% - unthinned, b) 35% at 55 months, c) 35% at 81 months, d) 70% at 81 months, removing sprouts in the thinned plant stumps and, e) 70% at 81 months, without coppice sprouts removal. By the age of 141 months, the Weibull distribution showed higher number of trees in the smallest diameter classes for the unthinned treatment. The 70% thinning, with thinned coppice sprouts removal, presented higher number of individuals in the largest diameter classes. Height and yield were the smallest with the removal of 70% of the trees at 81 months, maintaining coppice sprouts. The afterthinning periodic annual increment was greater by thinning 35% of the trees at 55 months resulting in greater number of trees in the largest diameter classes as compared to the other treatments. Yield was higher for the unthinned treatment. The results of this study indicated that thinning 70% of the trees at the age of 81 months, with coppice sprout removal, could be recommended to obtain trees of larger diameter for multiproduct.

PLANT GROWTH-PROMOTING MICROBIAL INOCULANT FOR Schizolobium parahyba pv. parahyba

ABSTRACTSchizolobium parahyba pv. amazonicum (Huber ex Ducke) Barneby (paricá) occurs naturally in the Amazon and is significant commercial importance due to its rapid growth and excellent performance on cropping systems. The aim of this paper was to evaluate a microbial inoculants such as arbuscular mycorrhiza fungi (AMF) and Rhizobium sp. that promote plant growth. The inocula was 10 g of root colonized and spores of Glomus clarum and/or 1 mL of cell suspension (107 CFU/mL) of Rhizobium sp. and/or 100 g of chemical fertilizer NPK 20-05-20 per planting hole. The experimental design was complete randomized blocks with five replications and eight treatments (n = 800). Plant height, stem diameter and plant survival were measured. The results were tested for normality and homogeneity of variances and analyzed by ANOVA and Tukey test (p < 0.05). Rhizobium sp and AM fungi showed no effect on plant growth. Environmental factors probably influenced the effectiveness of symbiosis of both microorganisms and plant growth. The chemical fertilizer increased S. parahyba growth. During the first 120 days plants suffered with drought and frost, and at 180 days plants inoculated with microorganism plus chemical fertilizer showed higher survival when compared with control. The results showed that the microbial inoculants used showed an important role on plant survival after high stress conditions, but not in plant growth. Also was concluded that the planting time should be between November to December to avoid the presence of young plants during winter time that is dry and cold.

Estimation of transpiration of the 'Valencia' orange young plant using thermal dissipation probe method

Most studies on measures of transpiration of plants, especially woody fruit, relies on methods of heat supply in the trunk. This study aimed to calibrate the Thermal Dissipation Probe Method (TDP) to estimate the transpiration, study the effects of natural thermal gradients and determine the relation between outside diameter and area of xylem in 'Valencia' orange young plants. TDP were installed in 40 orange plants of 15 months old, planted in boxes of 500 L, in a greenhouse. It was tested the correction of the natural thermal differences (DTN) for the estimation based on two unheated probes. The area of the conductive section was related to the outside diameter of the stem by means of polynomial regression. The equation for estimation of sap flow was calibrated having as standard lysimeter measures of a representative plant. The angular coefficient of the equation for estimating sap flow was adjusted by minimizing the absolute deviation between the sap flow and daily transpiration measured by lysimeter. Based on these results, it was concluded that the method of TDP, adjusting the original calibration and correction of the DTN, was effective in transpiration assessment.

Spraying systems and traveling speed in the deposit and spectrum of droplets in cotton plant

ABSTRACT Tractor traveling speed can influence the quality of spraying depending on the application technology used. This study aimed to evaluate the droplet spectrum, the deposition and uniformity of spray distribution with different spraying systems and traveling speeds of a self-propelled sprayer in two phenological stages of the cotton plant (B9 and F13). The experimental design was randomized blocks and treatments were three spraying techniques: common flat spray tips; tilted flat jet with air induction, at 120 L ha-1; and rotary atomizer disk, 20 L ha-1, combined with four traveling speeds: 12, 15, 18 and 25 km h-1, with four replications. Spraying deposition was evaluated for both leaf surfaces from the cotton plant apex and base (stage B9) and middle part of the plant (stage F13) with a cupric marker. A laser particle analyzer also assessed the droplet spectrum. The centrifugal power spray system produces more homogeneous droplet spectrum and increased penetration of droplets into the canopy in both phenological stages. Variation on the operating conditions necessary for increased traveling speed negatively influences the pattern of spraying deposits.

Senecio spp. POISONING OF HORSES IN SOUTHERN BRAZIL

Cases of seneciosis in horses occurring in four farms in the state of Santa Catarina and in another in the state of Rio Grande do Sul, southern Brazil, are reported. S. brasiliensis or S. oxyphyllus or both were detected in four of the five properties. Five horses (one on each property) were necropsied, and tissues for histopathological examination were collected from four horses. Neurological signs, such as depression, ataxia, aimeless walking, circling, head pressing, faulty prehension of food, dysphagia and blindness were consistently observed. Other signs included inappetence, loss of weight, colic, subcutaneous edema, icterus and photodermatitis. At necropsy the livers were firmer and darker than normal and had accentuation of lobular pattern. Edema of the mesentery and ascites were observed in one horse. Main histopathological changes consisted of hepatic chiefly periportal fibrosis, hepatomegalocytosis and biliary hyperplasia. Marked cholestasis and morphological evidence of hepatic encephalopathy were seen respectively in the liver and brain of one of the horses.

Spontaneous poisoning by larvae of Perreyia flavipes (Pergidae) in sheep

From a flock of 175 Texel sheep 25 animals died after consumption of a sawfly larvae subsequently identified as Perreyia flavipes. The disease occurred in June-July 2006 on a farm located in the county of Encruzilhada do Sul, Rio Grande do Sul, Brazil. Although there were 11 cattle in the same paddock, none of them was affected. High numbers of compact masses containing up to 150 larvae were scattered in the paddock where the animals were grazing. Most affected sheep showed severe apathy during 24-36 h before death, but weakness, muscular tremors and depression were also observed. Necropsy was performed on six sheep and the main macroscopic lesions were hemorrhages in the subcutaneous tissues, endocardium, gallbladder wall, and abomasal mucosa. In all animals was found hydrothorax, hydropericardium, ascites, and mild jaundice. Edema in the abomasal folds, mesentery, perirenal tissues, and gallbladder wall were also seen. The livers were yellowish with disseminated pinpoint hemorrhages in the parenchyma and had an enhanced lobular pattern. Perreyia flavipes larval body fragments and heads were found in the forestomach contents of the six sheep. Feces were scant, dry and formed balls coated by mucus and streaks of blood. Similar contents were also present at the end of the cecum. Prominent microscopic lesions included severe and diffuse periacinar or massive necrosis of hepatocytes associated with multifocal random hemorrhages. Diffuse necrosis of lymphoid follicles in lymph nodes and Peyer's patches, lymphoid depletion and necrosis in germinative centers of the spleen, and diffuse vacuolization in the renal tubular epithelia were also seen.

Senecio brasiliensis (Asteraceae) poisoning in Murrah buffaloes in Rio Grande do Sul

Thirteen (14.4%) out of 90 Murrah buffaloes (Bubalus bubalis) became ill after con-sumption of Senecio brasiliensis, and 11 (12.2%) of them died. The buffaloes were kept in a highly Senecio brasiliensis infested area. The poisoning occurred in June-August 2006 on a farm in the county of Nova Prata, Rio Grande do Sul, southern Brazil. Clinical signs included weakness, apathy, progressive weight loss, permanent decubitus, and diarrhea. Necropsy was performed in 2 of the 11 buffaloes that died. The pathological findings were typical of poisoning by pyrrolizidine alkaloids. High infestation of pastures with S. brasiliensis, severe drought, and consequent starvation were the main epidemiological factors associated with the poisoning here described.

Sheep poisoning by Panicum dichotomiflorum in northeastern Brazil

Different species of Panicum, including P. dichotomiflorum,have been reported as a cause of photosensitization in sheep, horses, cattle and goats. An outbreak of hepatogenous photosensitization occurred in 3 flocks of hair sheep in the Brazilian semiarid region. Eighty one out of 365 sheep were affected and 39 died. The main affected animals were nursing lambs and sheep younger than one year old. Donkeys, goats and cattle grazing in the same pasture were not affected. Clinical signs were edema of the head, followed by dermatitis, mainly in the face, ears, and croup, ocular discharge, corneal opacity with blindness, and redness of the coronary band and hoof. At necropsy of one affected lamb the liver was yellowish. Upon histologic examination scattered necrotic hepatocytes were observed in the liver and focal areas of necrosis of myocytes appeared in the heart. Samples of P. dicotomiflorum were analyzed by TLC and those containing saponins were isolated by HPLC using RP-C18 column and eluted with a mixture of MeOH and H2O. The isolated compounds were submitted to ¹H and 13C NMR spectroscopy. Reactions were positive to furostanol saponins with the same Rf of the standard protodioscin (0.21) and methylprotodioscin (0.32). The spectroscopic results indicated a mixture of (25R)- and (25S)-protodioscin isomers in a proportion of 3:1, and methylprotodioscin.

Accidental and experimental salinomycin poisoning in rabbits

An outbreak of salinomycin poisoning in rabbits is described. At least 27 out of 2,000 rabbits reared on a farm died after the coccidiostatic drug sulfaquinoxaline was substituted by salinomycin in the feed. An average of 26.9ppm salinomycin was detected in the ration given to the rabbits. Clinical signs included anorexia, apathy and bradykinesia, which progressed to incoordination and recumbency. Gross lesions consisted of pale areas in the skeletal muscles. The histopathological findings showed severe necrotic degenerative myopathy in association with infiltration of neutrophils and macrophages. One rabbit exhibited similar alterations in the myocardium. Mineralization was observed in the affected skeletal muscles in some cases. In order to verify if the poisoning was due to salinomycin, 20 rabbits were divided into five groups and a ration containing the drug at doses of 10, 25, 50, 75 and 100ppm was given. The administration of doses higher than 50ppm resulted in manifestation of the clinical signs seen in the outbreak of poisoning. It was concluded, that probably an error related to the mixture of salinomycin in the feed was the cause of deaths in the spontaneous outbreak of poisoning on the rabbit farm.

Acute and chronic nervous signs in cattle associated with Phalaris angusta poisoning in Argentina

Phalaris angusta is a South American natural grass that produces poisoning in sheep and cattle in Argentina and Brazil. Phalaris spp. can produce unrelated forms of poisoning in ruminants, acute and chronic syndromes. The objective of this paper was to describe an outbreak of acute and chronic Phalaris nervous syndrome in 53 of 980 fattening steers and heifers in a farm of Buenos Aires province. On September of 2006 the animals developed nervous signs and died after 3-5 days. The herd was removed to a phalarisfree pasture. Three months later (on December) 15 new clinical cases developed in the herd. Necropsy performed in one affected calf showed neither grossly nor microscopic changes. Microscopically, there were no major alterations in tissues. Nervous signs had been described in some field cases where neither pigment deposition nor axonal degeneration could be detected. Clinical findings displayed by affected cattle after consumption of Phalaris angusta pastures resemble those observed by other authors in Phalaris staggers. This is the first report in Argentina where both syndromes were seen in the same herd.