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The antileishmanial and immunomodulatory effects of propolis collected in Botucatu, São Paulo State, Brazil, were evaluated in Leishmania (Viannia) braziliensis experimental infection. The antileishmanial effect of propolis on promastigote forms was verified by reducing growth and by promoting morphologic alterations observed by scanning electron microscopy. In in vitro immunomodulatory assays, macrophages were pretreated with propolis and then infected with L. (V.) braziliensis. In vivo, supernatants from liver cells and peritoneal exudate of BALB/c mice pretreated with propolis and infected with Leishmania (107/mL promastigotes) were collected, and TNF-α and IL-12 were measured by ELISA. Macrophages incubated with propolis showed a significant increase in interiorization and further killing of parasites. An increased TNF-α production was seen in mice pretreated with propolis, whereas IL-12 was downregulated during the infection. In conclusion, Brazilian propolis showed a direct action on the parasite and displayed immunomodulatory effects on murine macrophages, even though the parasite has been reported to affect the activation pathways of the cell. The observed effects could be associated with the presence of phenolic compounds (flavonoids, aromatic acids, and benzopyranes), di- and triterpenes, and essential oils found in our propolis sample.

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Citrus canker is a very destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. The objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by Pseudomonas aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in foliar application to control citrus canker under greenhouse conditions, and (3) to identify antibiotic activity in orange leaf mesophyll infected with strain 306, by electron microscopy. Two pure bioactive compounds were isolated, an organocopper antibiotic compound (OAC) and phenazine-1-carboxamide. Phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The OAC showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 μg mL-1. In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d reduced lesion formation by about 97%. The concentration used was 500 times lower than that for the recommended commercial copper-based product. Electron microscopy showed that F3d altered the exopolysaccharide matrix and caused cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by inducing P. aeruginosa LV strain have a high potential to be used as a bioproduct to control citrus canker.

The late stages of microsporogenesis in the family Cyperaceae are marked by the formation of an asymmetrical tetrad, degeneration of three of the four nuclei resulting from meiosis and the formation of pseudomonads. In order to understand the cytological changes involved in the development of pseudomonads, a combination of 11 different techniques (conventional staining, cytochemistry procedures, immunofluorescence, FISH and transmission electron microscopy: TEM) were used to study the later stages of microsporogenesis in Rhynchospora pubera. The results demonstrated the occurrence of two cytoplasmic domains in the pseudomonads, one functional and the other degenerative, which are physically and asymmetrically separated by cell plate with an endomembrane system rich in polysaccharides. Other changes associated with endomembrane behaviour were observed, such as a large number of lipid droplets, vacuoles containing electron-dense material and concentric layers of endoplasmic reticulum. Concomitant with the isolation of degenerative nuclei, the tapetal cells also showed evidence of degeneration, indicating that both tissues under programmed cell death (PCD), as indicated by immunofluorescence and TEM procedures. The results are significant because they associate cellular polarisation and asymmetry with different cytoplasmic domains, and hence open new possibilities for studying cellular compartmentalisation and PCD.

Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is considered as a major problem in peach orchards. Copper and antibiotics are used to control, and biocontrol should be a new alternative with low environment impact. The objective was evaluated by the antibiotic activity of the metabolite produced by Pseudomonas aeruginosa LV strain. The free cells supernatant was fractionated with a serial organic solvent with crescent polarity and a dichloromethane phase was concentrated and lyophilised, and after was fractionated using vacuum liquid chromatography. The antibiotic activity of the F3 fraction containing an organometallic compound was tested on Xap in vitro and in a greenhouse conditions. Plants were sprayed with F3 before or after Xap infection and the results showed changes in exopolysaccharides and cell morphology. The F3 concentration of 450 µg•mL-1 was more effective. The results showed that F3 fraction could be a new alternative to control bacterial spot.

ResumoO silício é considerado um elemento benéfico às plantas, podendo trazer incrementos na produtividade e sanidade de diversas culturas. Nos vegetais, acumula-se principalmente nas áreas de máxima transpiração. Este trabalho teve por objetivo comparar o acúmulo de silício nas folhas bandeira de diferentes genótipos de trigo (Triticum aestivum L.), com o auxílio da Microscopia Eletrônica de Varredura (MEV). O experimento foi conduzido a campo, durante o ano agrícola de 2010, aonde foram utilizados oito genótipos de trigo (cultivares BRS 208, IPR 85, BRS Pardela, BRS 210, IPR 130, CD 104, BRS 220 e a linhagem WT 07106). Aos três meses após a semeadura, retiraram-se amostras das folhas para a análise de silício em MEV e espectroscopia de energia dispersiva de raios-X (EDS). Todos os genótipos avaliados acumularam corpos silicosos em suas epidermes foliares, sendo que esses corpos apresentaram formato arredondado e deposição diferenciada entre os diversos genótipos. Palavras-chave: Silício, Triticum aestivum, corpos silicosos, microscopia eletrônica de varredura, espectroscopia de energia dispersiva de raios-X AbstractSilicon is considered a beneficial element to plants and may increase productivity and health of many crops. In plants, silicon accumulates mainly in the areas of maximum transpiration. This study aimed to investigate and compare silicon accumulation in flag leaves of different genotypes of wheat (Triticum aestivum) with the aid of scanning electron microscopy (SEM). The experiment was conducted in the field during the growing season 2010, eight wheat genotypes (BRS 208, RPI 85, BRS Pardela, BRS 210, RPI 130, CD 104, BRS 220 and WT 07106 lineage) were used. Three months after sowing, the samples were collected from the leaves to perform the silicon analysis by SEM and energy dispersive X-ray (EDS). All genotypes accumulated silica bodies in their leaf epidermis, the bodies had a rounded shape and were deposited differently from one genotype to another.