Estudo de métodos naturais para redução de doenças fúngicas em sementes nativas da região Amazônica / Study of natural methods for reducing fungal diseases in native seeds in the Amazon region

Existe uma preocupação na produção de alimentos com a segurança sanitária desde o processo de cultivo até a sua expedição aos centros comerciais. Uma das maiores contaminações em sementes por suas características físicas e químicas, é a contaminação fúngica devida à acidez e umidade dos frutos. As doenças fúngicas entre elas, antracnose, vassoura de bruxa e podridão parda são consideradas importante doenças em pós colheita, ocorrendo, principalmente, sob condições de alta umidade relativa do ar e temperaturas elevadas (26ºC a 28ºC). Dentre as sementes da região Amazônica, destacam-se sementes de (cacau- Theobroma cacao L., pupunha- Bactris gasipaes, tucumã da Amazonas-Astrocaryum aculeatum), que apresentam problemas de contaminação fúngica durante o sistema de cultivo. Métodos de biocontroles com ação antimicrobiana: bactérias endofíticas, rizobactérias e fungo Trichoderma ssp, entre outros estão sendo estudados para a redução destas contaminações fúngicas em estudos in vitro e no campo. O objetivo deste trabalho é apresentar uma revisão bibliográfica sobre a utilização de métodos de biocontrole como uma alternativa promissora no manejo de doenças de plantas na fase de pós-colheita, com excelentes resultados em culturas de grande importância econômica. Assim novas alternativas ecologicamente sustentáveis demonstram a possibilidade de os produtos estudados serem utilizados no manejo da antracnose na pós-colheita.(AU)

There is a concern in food production with health security from cultivation process to its dispatch to redistribution centers. One of the biggest contaminations in seeds due to their physical and chemical characteristics, is the fungal contamination due to the acidity and humidity of the fruits. Fungal diseases including anthracnose, bruca's broom and brownrot are considered important diseases in post-harvest, occurring mainly under conditions of high relative humidity and high temperatures (26ºC to 28ºC). Among the seeds of the Amazon region, seeds of de (cacau- Theobroma cacao L., pupunha- Bactris gasipaes, tucumã da Amazonas- Astrocaryum aculeatum ), that present problems fungals contamination during in their growing cultures sistems. Biocontrol methods with antimicrobial action: endophytic bacteria, rhizobacteria and the fungus Trichoderma ssp, among others, are being studied to reduce these fungal contaminations in in vitro and field studies. The objective of this work is to present a bibliographic review on the use of biocontrol methods as an alternative that is promising in the management of plant diseases in the post-harvest phase, with excellent results in crops of great economic importance. Thus, new ecologically sustainable alternatives demonstrate the possibility of the studied products to be used in the management of anthracnose in the post-harvest period.(AU)

Corynespora cassiicola in soybean seeds: incidence and transmission / Corynespora cassiicola em sementes de soja: incidência e transmissão

The fungus Corynespora cassiicola, the causal agent of the target spot in soybeans, has been considered, from the seed pathology point of view, a seed-borne pathogen of limited importance. Therefore, little importance has been given to the role of the seeds in the transmission of this pathogen. The objectives of this study were to determine the incidence of C. cassiicola in soybean seeds and evaluate the effects of this seed-borne pathogen, inoculated in the seeds, concerning to physiological and epidemiological parameters. The experiments were carried out at TAGRO and Embrapa Western Agriculture under lab (blotter test and seed germination test) and greenhouse conditions (growing on test). The fungus C. cassiicola was detected in 11.3% of the 639 seed samples analyzed, with an average incidence of 0.91% and a maximum of 8.5%. The transmission of C. cassiicola from the seeds to above-ground parts of soybean seedlings was demonstrated, by pathogen establishment on the cotyledon, showing circular lesions with concentric rings, reddish-brown in the center and surrounded by a yellowish-green halo, as a typical symptom of target spot. Reddish-brown lesions on the roots and stem of the seedlings were also observed. Considering a sample seed with 66.0% of C. cassiicola incidence, the symptomatic transmission based on cotyledon symptoms was 42.2%, corresponding to a transmission rate of 2.4:1. This is the first report, in a quantified way, about the transmission of C. cassiicola from the seeds to above-ground parts of soybean seedlings. When compared to non-inoculated seeds, seed germination, seedling emergence, and seedling initial development were influenced by the presence of the pathogen in the seeds, with the lowest values being observed when the seeds were inoculated.

O fungo Corynespora cassiicola, agente causal da mancha alvo da soja, tem sido considerado, do ponto de vista da patologia de sementes, um patógeno de importância limitada. Por esse motivo, pouca importância foi dada em relação ao papel das sementes na transmissão desse patógeno. Os objetivos desse trabalho foram determinar a incidência de C. cassiicola em sementes de soja bem como avaliar os efeitos da presença desse patógeno, inoculado nas sementes, com parâmetros fisiológicos e epidemiológicos. Os experimentos foram conduzidas na TAGRO e na Embrapa Agropecuária Oeste e constaram de testes de laboratório (blotter test e teste padrão de germinação) e de casa de vegetação (growing on test). O fungo C. cassiicola foi detectado em 11,3% das 639 amostras de sementes analisadas, com incidência média de 0,91% e a máxima de 8,5%. A transmissão de C. cassiicola, da semente para a parte aérea das plântulas de soja foi demonstrada, pelo estabelecimento do patógeno nos cotilédones, apresentando lesões circulares com anéis concêntricos, marrom-avermelhada no centro e com presença de halos amarelados, característicos da mancha alvo. Lesões radiculares e no colo das plântulas, de coloração marrom avermelhada, também foram observadas. Considerando a incidência de C. cassiicola na semente de 66,0%, a transmissão sintomática do fungo baseada em sintomas no cotilédone, foi de 42,2%, o que representou uma taxa de transmissão de 2,4:1. Esse é o primeiro relato, de forma quantificada, da transmissão de C. cassiicola das sementes para a parte aérea das plântulas de soja. Em comparação às sementes não inoculadas, a germinação das sementes, emergência e o desenvolvimento inicial das plântulas foram influenciados pela presença do patógeno nas sementes, com os menores valores sendo observados quando as sementes foram inoculadas.

Incidence of base rot and wilt, sanitary severity and influence about seed pathology by cultivars of common bean (Phaseolus vulgaris) / Incidência de podridão-do-colo e severidade fitossanitária e impacto na patologia de sementes de cultivares comerciais de feijoeiro-comum (Phaseolus vulgaris)

The objective of this work was to conduct a temporal evaluation of incidence of rot base and sanitary severity, and to relate the impact on the seed pathology of common bean cultivars. In the 2015-2016 harvest, in the city of Ipameri, Goiás, ten cultivars of common bean were evaluated (BRS Estilo©, BRS Pérola©, IPR Tangará©, IPR Tuiuiú©, IPR Uirapuru©, IAC Milênio©, Imperador©, IAC F3 R2©, IAC OTG© and IPR Campos Gerais©) and distributed into five blocks, totaling 40 experimental units. The incidence of wilt and base rot and sanitary severity were analyzed by taking ten random samples per block at 21, 28, 56, 63 and 69 days after planting. At the end of 120 days, a total of 20 plants were harvested per cultivar, and 250 seeds were harvested for application of the Blotter Test method. From 21 to 69 days after planting, the cultivars BRS Pérola© and IPR Campos Gerais© deserve to be highlighted for presenting the lowest incidence of wilt in the reproductive and vegetative cycles. The cultivar BRS Pérola© showed the lowest incidence of wilt and sanitary severity. In the analysis of harvested seeds, the cultivar BRS Pérola© presented high physiological quality for all evaluated parameters. On the other hand, Cramberry (OTG)© showed low physiological potential in germination and vigor tests.(AU)

O objetivo deste trabalho foi realizar uma avaliação temporal da incidência de podridão-do-colo e severidade fitossanitária, e relacionar o impacto na patologia de sementes de cultivares comerciais de feijoeiro-comum. Na safra 2015-2016, no município de Ipameri, Goiás, foram avaliados dez cultivares de feijoeiro (BRS Estilo©, BRS Pérola©, IPR Tangará©, IPR Tuiuiú©, IPR Uirapuru©, IAC Milênio©, Imperador©, IAC F3 R2©, IAC OTG© e IPR Campos Gerais©), distribuídos em cinco blocos, totalizando 40 unidades experimentais. Analisou-se temporalmente a incidência da murcha e ­podridão-do-colo e a severidade fitossanitária tomando dez amostragens aleatórias por bloco aos 21, 28, 56, 63 e 69 dias após o plantio. Ao final dos 120 dias, colheu-se um total de 20 plantas por cultivar, sendo extraídas 250 sementes de cada para aplicação do método "Blotter Test". Dos 21 aos 69 dias após o plantio, merecem destaque os cultivares BRS Pérola© e IPR Campos Gerais©, por apresentarem as menores incidências de murcha nos ciclos reprodutivo e vegetativo. O cultivar BRS Pérola© apresentou as menores incidências de murchas e severidade fitossanitária. Na análise de sementes colhidas, o cultivar BRS Pérola© apresentou elevada qualidade fisiológica para todos os parâmetros avaliados. Em contrapartida, o cultivar Cramberry (OTG)© mostrou baixo potencial fisiológico nos testes de germinação e vigor.(AU)

Cryopreservation at -75 °C of Agaricus subrufescens on wheat grains with sucrose

Abstract Agaricus subrufescens is a basidiomycete which is studied because of its medicinal and gastronomic importance; however, less attention has been paid to its preservation. This study aimed to evaluate the effect of sucrose addition to substrate and cryotube on the viability of Agaricus subrufescens cryopreserved at -20 °C and at -75 °C for one and two years. Zero, 10% or 20% sucrose was added to potato dextrose agar or wheat grain. The mycelia were cryopreserved in the absence of cryoprotectant or with sucrose solutions at 15%, 30% or 45%. After one or two years at -75 °C or at -20 °C, mycelia were thawed and evaluated about viability, initial time of growth, colony diameter and genomic stability. Cryopreservation at -20 °C is not effective to keep mycelial viability of this fungus. Cryopreservation at -75 °C is effective when sucrose is used in substrates and/or cryotubes. Without sucrose, cryopreservation at -75 °C is effective only when wheat grains are used. Physiological characteristic as mycelial colony diameter is negatively affected when potato dextrose agar is used and unaffected when wheat grain is used after two-year cryopreservation at -75 °C. The fungus genome does not show alteration after two-year cryopreservation at -75 °C.

Promotion of iron nutrition and growth on peanut by Paenibacillus illinoisensis and Bacillus sp. strains in calcareous soil

ABSTRACT This study aimed to explore the effects of two siderophore-producing bacterial strains on iron absorption and plant growth of peanut in calcareous soil. Two siderophore-producing bacterial strains, namely, YZ29 and DZ13, isolated from the rhizosphere soil of peanut, were identified as Paenibacillus illinoisensis and Bacillus sp., respectively. In potted experiments, YZ29 and DZ13 enhanced root activity, chlorophyll and active iron content in leaves, total nitrogen, phosphorus and potassium accumulation of plants and increased the quality of peanut kernels and plant biomass over control. In the field trial, the inoculated treatments performed better than the controls, and the pod yields of the three treatments inoculated with YZ29, DZ13, and YZ29 + DZ13 (1:1) increased by 37.05%, 13.80% and 13.57%, respectively, compared with the control. Based on terminal restriction fragment length polymorphism analysis, YZ29 and DZ13 improved the bacterial community richness and species diversity of soil surrounding the peanut roots. Therefore, YZ29 and DZ13 can be used as candidate bacterial strains to relieve chlorosis of peanut and promote peanut growth. The present study is the first to explore the effect of siderophores produced by P. illinoisensis on iron absorption.

Introduction of a synthetic Thermococcus-derived α-amlyase gene into barley genome for increased enzyme thermostability in grains

Background: The enzymes utilized in the process of beer production are generally sensitive to higher temperatures. About 60% of them are deactivated in drying the malt that limits the utilization of starting material in the fermentation process. Gene transfer from thermophilic bacteria is a promising tool for producing barley grains harboring thermotolerant enzymes. Results: Gene for α-amylase from hydrothermal Thermococcus, optimally active at 75­85°C and pH between 5.0 and 5.5, was adapted in silico to barley codon usage. The corresponding sequence was put under control of the endosperm-specific promoter 1Dx5 and after synthesis and cloning transferred into barley by biolistics. In addition to model cultivar Golden Promise we transformed three Slovak barley cultivars Pribina, Levan and Nitran, and transgenic plants were obtained. Expression of the ~50 kDa active recombinant enzyme in grains of cvs. Pribina and Nitran resulted in retaining up to 9.39% of enzyme activity upon heating to 75°C, which is more than 4 times higher compared to non-transgenic controls. In the model cv. Golden Promise the grain α-amylase activity upon heating was above 9% either, however, the effects of the introduced enzyme were less pronounced (only 1.22 fold difference compared with non-transgenic barley). Conclusions: Expression of the synthetic gene in barley enhanced the residual α-amylase activity in grains at high temperatures.

Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L)

ABSTRACT We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU) and one biocontrol agent (Pseudomonas fluorescens strain PF1) for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

Qualidade higienicos sanitária de produtos sólidos prontos para o consumo (petiscos e similares) comercializados na região de Catanduva – SP / Sanitary hygienic quality of solid products ready for consumption (snacks) marketed in the Catanduva region - SP

Petiscos compreendem sementes comestíveis, salgadas, cruas, doces, torradas, fritas, condimentadas ou não, podendo também ser produtos doces, salgados, fritos, assados, compactados, incluindo torresmos e similares. Na maioria das vezes são consumidos como aperitivos ou acompanhamentos de alguns tipos de pratos, variando conforme sua espécie e região. O objetivo deste trabalho foi avaliar a qualidade higienicossanitária de diferentes amostras de produtos sólidos prontos para o consumo (petiscos e similares), comercializados na região de Catanduva-SP, por meio de metodologias internacionalmente reconhecidas. Para tanto, 20 amostras de diferentes marcas comerciais, dentro do prazo de validade, foram submetidas às seguintes análises: determinação do Número Mais Provável (NMP) de coliformes totais e termotolerantes, pesquisa de Escherichia coli e Salmonella spp. Os resultados obtidos para coliformes termotolerantes revelaram que todas as amostras (100%) encontravam-se de acordo com o padrão federal vigente. No entanto, para Salmonella spp. as análises mostraram que 50% das amostras estavam em desacordo com o padrão federal vigente, podendo ser classificadas como "produtos em condições sanitárias insatisfatórias" e, por conseguinte, "produtos impróprios para o consumo humano".

Snacks include edible seeds, salted, raw, sweet, toast, fried, spicy or not, can also be sweet products, salty, fried, baked, packaged, including greaves and the like. Most often are eaten as appetizers or side dishes, varying according to their species and region. The objective of this study was to evaluate the sanitary quality of different samples of solid products ready for consumption (and similar snacks), marketed in the region Catanduva-SP, through internationally recognized methodologies. For this purpose, samples of different brands within the validity period were subjected to the following tests: determination of Most Probable Number (MPN) of total and thermotolerant coliforms, Escherichia coli and Salmonella spp research. The results obtained for thermotolerant coliforms revealed that all samples (100%) were in accordance with the federal standard force. However, for Salmonella spp. the analysis showed that 50% of the samples weren't in accordance with the current federal standard, which can be classified as "products in poor sanitary conditions" and therefore "products unfit for human consumption".

Enriquecimiento diferencial de Pseudomonas spp. en el rizoplano de distintas especies cultivadas / Selective enrichment of Pseudomonas spp. in the rhizoplane of different plant species

En contraste con la simbiosis entre rizobios y leguminosas, la especificidad de las Pseudomonas en la colonización radicular parece menos estricta. Sin embargo, estudios sobre la diversidad bacteriana del nicho rizosférico resaltan la influencia de la especie vegetal en la selección específica de ciertos microorganismos a partir de la flora residente del suelo. Para evaluar el efecto que los cultivos extensivos de nuestro país tienen sobre la estructura de las comunidades de Pseudomonas, se realizaron experimentos con plantas trampa, partiendo de semillas de trigo, maíz y soja desinfectadas superficialmente y sembradas en un mismo suelo prístino. A partir de las suspensiones representativas de la microflora del rizoplano, se realizaron recuentos en placa en medio selectivo para Pseudomonas. El conjunto de colonias originado a partir de los distintos rizoplanos se utilizó como fuente de ADN para analizar la estructura de comunidad a través del perfil de restricción de amplicones de los genes oprF y gacA. El análisis comparativo de estos perfiles agrupó a las muestras por especie de planta y las distinguió del patrón obtenido a partir del suelo prístino. La secuenciación parcial del gen 16S ADNr de aislamientos bacterianos representativos confirmó la existencia de genotipos enriquecidos diferencialmente en el rizoplano de cada especie vegetal. Estos resultados apoyan la hipótesis de la existencia de mecanismos de selección específica de estirpes de Pseudomonas a partir de la flora nativa del suelo en la interacción cooperativa entre estas PGPR y las raíces de diferentes cultivos como trigo, soja y maíz

In contrast to rhizobia-legume symbiosis, the specificity for root colonization by pseudomonads seems to be less strict. However, several studies about bacterial diversity in the rhizosphere highlight the influence of plant species on the selective enrichment of certain microorganisms from the bulk soil community. In order to evaluate the effect that different crops have on the structure of pseudomonad community on the root surface, we performed plant trap experiments, using surface-disinfected maize, wheat or soybean seeds that were sown in pots containing the same pristine soil as substrate. Rhizoplane suspensions were plated on a selective medium for Pseudomonas, and pooled colonies served as DNA source to carry out PCR-RFLP community structure analysis of the pseudomonads-specific marker genes oprF and gacA. PCR-RFLP profiles were grouped by plant species, and were distinguished from those of bulk soil samples. Partial sequencing of 16S rDNA genes of some representative colonies of Pseudomonas confirmed the selective enrichment of distinctive genotypes in the rhizoplane of each plant species. These results support the idea that the root systems of agricultural crops such as soybean, maize and wheat, select differential sets of pseudomonads from the native microbial repertoire inhabiting the bulk soil

Potential of Microbispora sp. V2 as biocontrol agent against Sclerotium rolfsii, the causative agent of southern blight of Zea mays L (Baby corn)–in vitro studies.

The study was undertaken with the aim of exploring novel and beneficial agro activities of rare actinomycetes like Microbispora sp. V2. The antagonistic activity of Microbispora sp. V2 was evaluated as a biocontrol agents against Sclerotium rolfsii, a soil-borne fungal plant pathogen. The methodology performed for evaluation of biocontrol agent was in vitro evaluation assay which comprised of three tests viz., cellophane overlay technique, seed germination test and Thiram (fungicide) tolerance of Microbispora sp. V2. The isolate was found to inhibit the fungal pathogen Sclerotium rolfsii to 91.43% in cellophane assay. In seed germination assay, Microbispora sp. V2 treated seeds resulted in 25.75% increased germination efficiency, as compared to seeds infected by Sclerotium rolfsii. The isolate Microbispora sp. V2 could tolerate 1000 µg mL-1 of Thiram (fungicide). The in vitro assay studies proved that Microbispora sp. V2 can be used as antifungal antagonist and thus posses’ great potential as biocontrol agent against southern blight caused by Sclerotium rolfsii in Zea mays L (Baby corn) which causes large economical losses.

Search for endophytic diazotrophs in barley seeds

Eight endophytic isolates assigned to Pseudomonas, Azospirillum, and Bacillus genera according to pheno-genotypic features were retrieved from barley seeds under selective pressure for nitrogen-fixers. Genetic relationships among related isolates were investigated through RAPD. Six isolates displayed nitrogen-fixing ability, while all could biosynthesize indolacetic acid in vitro and showed no antibiosis effects against Azospirillum brasilense Az39, a recognized PGPR.

Distribution of aflatoxins and micro organisms in peanut and sunflower seed products and their potential health Hazards

Aflatoxins are mould metabolites of Aspargillus flavus and parasiticus that contaminate foodstuffs stored in warm moist places. These toxins are hepatotoxic and produce hepatocellular carcinoma in animals and man. To determine the presence of aflatoxins and microorganisms in ready to consume products of peanuts and sunflower seeds of an edible oil processing factory. Five hundred grams each of peanut kernels, peanut pellets, sunflower seed pellets, peanut oil and sunflower seed oil produced by a local oil extracting factory were supplied for extraction and estimation of aflatoxins and microorganisms like Salmonella, Escherichia coli [E.coli], Bacillus and Moulds. Aflatoxins B[1], B[2], G[1] and G[2] were extracted in chloroform and concentration was measured using silica gel columns. The quantitative estimation of these aflatoxins B[1], B[2], G[1] and G[2] was done by fluorescence evaluation on Thin Layer Chromatograms. All test samples contained four types of aflatoxins. The highest aflatoxin values were seen in the pellets and lowest in refined oils. All samples contained higher content of aflatoxins B[1] and B[2] than G[1] and G[2]. Refined peanut oil contained much lower aflatoxin than the sunflower seed oil. This study has also identified the presence of several types of microorganisms such as Salmonella, E. coli, Bacillus and Moulds in ready to eat peanut and sunflower seed products. Detection of high levels of aflatoxins and microorganisms in ready to eat food stuff should be a concern for food regulatory agencies since these products are consumed daily by the common man and their cumulative effect on the body might be adding to liver cancer in the population. Food regulatory agencies should regularly carry out thorough surveillance on food stuff

Ochratoxigenic fungi associated with green coffee beans (Coffea arabica L.) in conventional and organic cultivation in Brazil

The genera Aspergillus comprises species that produce mycotoxins such as aflatoxins, ochratoxins and patulin. These are cosmopolitan species, natural contaminants of agricultural products. In coffee grains, the most important Aspergillus species in terms of the risk of presenting mycotoxins belong to the genera Aspergillus Section Circumdati and Section Nigri. The purpose of this study was to assess the occurrence of isolated ochratoxigenic fungi of coffee grains from organic and conventional cultivation from the South of Minas Gerais, Brazil, as well as to evaluate which farming system presents higher contamination risk by ochratoxin A (OTA) produced by fungi. Thirty samples of coffee grains (Coffea arabica L.) were analysed, being 20 of them of conventional coffee grains and 10 of them organic. The microbiological analysis was done with the Direct Plating Technique in a Dichloran Rose Bengal Chloramphenicol Agar (DRBC) media. The identification was done based on the macro and micro morphological characteristics and on the toxigenic potential with the Plug Agar technique. From the 30 samples analysed, 480 filamentous fungi of the genera Aspergillus of the Circumdati and Nigri Sections were isolated. The ochratoxigenic species identified were: Aspergillus auricoumus, A. ochraceus, A. ostianus, A. niger and A. niger Aggregate. The most frequent species which produces ochratoxin A among the isolated ones was A. ochraceus, corresponding to 89.55%. There was no significant difference regarding the presence of ochratoxigenic A. ochreceus between the conventional and organic cultivation systems, which suggests that the contamination risk is similar for both cultivation systems.

Caracterización de semillas de linaza (Linum usitatissimum L.) cultivadas en Venezuela

En los últimos años se ha promovido el consumo de linaza (Linum usitatissimum L.) como alimento funcional por sus beneficios a la salud, atribuibles principalmente a su contenido de ácidos grasos omega-3, lignanos, y fibra dietaria. En este estudio se evaluó la calidad microbiológica, composición química y las propiedades antioxidantes de la semilla de linaza cultivada en Venezuela y se comparó con una variedad canadiense de amplia venta en el país. Se determinaron coliformes totales, mohos y levaduras, S. aureus, y esporulados de los géneros Bacillus (aerobios) y Clostridium (anaerobios), humedad, grasas, proteínas, fibra dietética total, soluble e insoluble, mucílago, minerales, perfil de ácidos grasos, contenido de HCN equivalente, aw, color, polifenoles y propiedades antioxidantes como Eficiencia Antirradical (EA), concentración de antioxidante necesario para disminuir la concentración inicial en 50 % (EC50) y el tiempo necesario para alcanzar la EC50 (TEC50). Se determinaron diferencias significativas en la composición de las semillas, resaltando su elevado contenido de grasa, proteínas, ácido alfa-linolénico y fibra dietaria. Se observaron diferencias en el contenido de mucílago, pero no en el de fibra soluble, insoluble y total. La concentración de HCN equivalente en ambas semillas es del orden de 40 mg/100 g, lo cual no representa riesgos a la salud, si se consideran sus formas de consumo. La linaza venezolana contiene mayor contenido de polifenoles que la canadiense, pero la capacidad antioxidante de esta última es mayor; ambas tienen una EA calificada como media (TEC50>30 min).

Characterization of flaxseed (Linum usitatissimum L.) grown in Venezuela. In recent years, the consumption of flaxseed (Linum usitatissimum L.) has been promoted as a functional food for its health benefits, mainly attributable to its content of omega-3 fatty acids, lignans and dietary fiber. This study evaluated the microbiological quality, chemical composition and antioxidant properties of flaxseed grown in Venezuela and compared them to the values of a Canadian variety widely sold in the country. Total coliforms, molds and yeasts, S. aureus and sporulated of the genera Bacillus (aerobic) and Clostridium (anaerobic), moisture, fat, protein, total dietary fiber, soluble and insoluble, mucilage, minerals, fatty acid profile, equivalent HCN content, aw, color, polyphenols and antioxidant properties, like antiradical efficiency (AE), concentration of antioxidant needed to decrease the initial concentration by 50 % (EC50) and the time required to reach the EC50 (TEC50) were evaluated. Significant differences in seed composition were determined, where its high content of fat, protein, alfalinolenic acid and dietary fiber stand out. Differences were observed in the mucilage content, but not in soluble, insoluble and total fiber content. Equivalent HCN concentration in both seeds is in the order of 40 mg/100 g, which poses no health risks, considering their consumption patterns. Venezuelan flaxseed contains higher content of polyphenols than the Canadian does, but the antioxidant capacity of the latter is higher; both have an EA rated as average and a slow reaction time (TEC50> 30 min).

Fungos veiculados por sementes comerciais de braquiária / Fungi associated to commercial seed of braquiaria grass

Este trabalho objetivou avaliar a qualidade sanitária de 50 lotes comerciais de sementes de braquiária, produzidos em diferentes regiões nas safras de 2004-2005 e 2005-2006. Sementes de Brachiaria brizantha cvs. Marandu e Xaraés, B. decumbens cv. Basilisk, B. humidicola cv. Humidicola e B. ruziziensis cv. Ruziziensis, destinadas ao comércio interno, foram submetidas ao teste de sanidade pelo método de papel de filtro. Adicionalmente, avaliou-se a sanidade de sementes de 'Marandu' (2 lotes) e 'Basilisk' (1 lote) destinadas à exportação. As sementes foram distribuídas sobre papel de filtro acondicionado em gerbox e incubadas a 20º C, com fotoperíodo de 12h, durante sete dias. Os fungos secundários ou de armazenamento (FSA) mais frequentemente detectados nos lotes de braquiária foram Aspergillus sp. e Rhizopus sp. Quanto aos fungos potencialmente patogênicos (FP), constatou-se elevada frequência dos gêneros Bipolaris. Curvularia. Fusarium e Phoma. Em geral, foi elevada a incidência de Bipolaris sp., Fusarium sp. e Phoma sp. nas sementes. A ocorrência de Phoma sp. foi crítica, pois 42% dos lotes registraram índices superiores a 70%. Bipolaris sp., Fusarium sp. e Phoma sp. também foram associados às sementes de braquiária tipo exportação, em alguns casos, com incidência considerável. Os resultados revelaram que as sementes comerciais de braquiária apresentam baixa qualidade sanitária e que, em todas as regiões produtoras, existe pelo menos um fator afetando a sanidade dessas sementes.

This work aimed to evaluate the sanitary quality of 50 commercial lots of seeds of braquiaria grass, produced in different regions in the crop of 2004­2005 and 2005­2006. The lots consisted of seeds of the cultivars Brachiaria brizantha cvs. Marandu and Xaraes, B. decumbens cv. Basilisk, B. humidicola cv. Humidicola and B. ruziziensis cv. Ruziziensis. Additionally, seeds of 'Marandu' (2 lots) and 'Basilisk' (1 lot) for exportation were analyzed. The blotter test was used, at 20º C under alternating light and darkness in a 12h photoperiod, for 7 days. Aspergillus sp. and Rhizopus sp. were the secondary or storage fungi with greatest frequency in lots of seeds. High frequency of potential pathogenic fungi, specifically of the Bipolaris. Curvularia. Fusarium and Phoma genera, was observed. In general, there was a high incidence of Bipolaris sp., Fusarium sp. and Phoma sp. in braquiaria grass seeds. The occurrence of Phoma sp. was severe, because 42% of the lots showed incidence superior to 70%. Bipolaris sp., Fusarium sp. and Phoma sp. were associated to braquiaria grass seeds for exportation, in some cases, with significant incidence. The results evidenced the low sanitary quality of commercial seeds of braquiaria grass, and demonstrated that in all producer regions there is at least one factor affecting the sanitary quality of these seeds.

Evaluación agronómica de genotipos de sorgo y millo (Sorghum vulgare) forrajeros para alimentación de bovinos en el medio Sinú / Agronomic evaluation of forages sorghum (Sorghum vulgare) and millo genotypes for feeding bovine in the Sinú valley

Objetivo. Evaluar siete genotipos de millo y cinco genotipos de sorgo, para determinar el rendimiento forrajero y su utilidad en la alimentación de bovinos en el valle del medio Sinu. Materiales y métodos. Las semillas de sorgo y millo (Sorghum vulgare), fueron materiales híbridos y variedades tipo comercial. Se utilizó un diseño de bloques completos al azar con 4 cuatro repeticiones para millo y tres para sorgo. Resultados. Respecto al vigor los genotipos de millo que mejor comportamiento presentaron fueron el redondo cuba y blanco panoja larga; en sorgo el LC 603, el P-8239 y el DR-1125. Los millos que mostraron mayor senescencia fueron el cuarentano alto, el bastón y el blanco panoja larga; en sorgo los de mayor senescencia fueron el P-8239, el LC 603 y el 74 CO. La mayor producción de forraje verde y materia seca la presentaron los genotipos de millo, el batea cuba, el redondo cuba y el blanco panoja larga, los de sorgo fueron el blanco criollo y el DR-1125. El mayor rendimiento de grano fue de los genotipos el batea cuba y bastón en millo, y en sorgo fueron DR-1125 y LC 603. Se seleccionaron como materiales de buen comportamiento dentro de todos los evaluados el batea cuba, redondo cuba, y blanco panoja larga en millo y el blanco criollo y DR-1125 en sorgo. Conclusiones. Los genotipos de millo que mejor comportamiento presentaron fueron en su orden por rendimiento (ton/ha): el batea cuba, el redondo cuba y el blanco panoja larga (ton/ha), obteniéndose una mayor capacidad de carga animal. Los genotipos de mejor comportamiento de sorgo fueron el blanco criollo y el DR-1125.

Colonization of Bacillus spp. on seeds and in plant rhizoplane.

Seed coating, dipping and Scanning Electron Microscopy (SEM) were employed to study bacterial and fungal colonization of the seeds and rhizoplane of maize (Zea mays L.) during the early stages of growth. Isolation of Bacillus spp. entailed screening soil bacteria with potential growth stimulation and plant pathogen suppressive abilities isolated from the rhizospheres and rhizoplanes of vegetable crops. The bacterial colonization of the spermosphere was 90%. When the coated seeds were fully germinated, bacteria moved to the emerging radicle. Virtually no bacteria occurred on the root tip both for the treated and untreated. However, colonization was 20% in the basal portion of the roots close to the seed-root junction. SEM observations showed that the bacterial cells were arranged linearly and laterally on the growing root axis. This phenomenon was more noticeable in the seedlings dipped in the bacterial culture on the 3rd day after germination. The results indicate that attachment to the seed coat and the rhizoplane by the plant growth-promoting rhizobacterium (PGPR) is an important factor in the successful colonization of the rhizoplane. The significance of the work is to ascertain that the inoculated Bacillus spp. adhered to and established in the rhizoplane of maize. It can therefore be used as a PGPR and as a biocontrol agent.

Immature embryo: a useful tool for oil palm (Elaeis guineensis Jacq. ) genetic transformation studies

Oil palm (Elaeis guineensis Jacq.) is the highest yielding oil-bearing crop. However, being a perennial crop, genetic improvement of oil palm is extremely slow. Indeed, compared to other annual oil crops such as soybean and rapeseed, genetic manipulations remained less important. Therefore, to remain competitive, oil palm growers and breeders need new and novel approaches. In this report, the potential of immature embryos (IE) as a useful tool for oil palm genetic transformation studies was evaluated. It was evident that IEs were amenable to both direct and Agrobacterium-mediated gene transfer. Due to the abundant supply of IE, optimization of biolistic and Agrobacterium-mediated gene transfer into IEs were easily carried out. Transient transformation frequencies were comparable to other plant systems reported, with as high as 97.4 percent recorded for biolistic and 64.4 percent for Agrobacterium-mediated gene transfer. Like most moncots, oil palm tissues were less sensitive to kanamycin, geneticin and chloramphenicol. Instead, both hygromycin and phosphinotrycin were toxic 20 mg/l, making both suitable candidates for selecting putative transformants. IEs were also more responsive to in vitro manipulations as compared to other explants such as leaf and root tissues. Rapid in vitro response to callusing and embryogenesis or rapid and highly efficient direct germination resulted in a shorter culture period. This would minimize the production of abnormal clonal palms, which has been associated to chromosomal aberration due to prolonged time in culture. In addition, IEs also allows rapid and direct introduction of elite genes into breeding programs and in biclonal seed production.

Pathogenic effects of Salmonella enterica subspecies enterica serovar Typhimurium on sprouting and growth of maize.

The study was undertaken to understand effects and survival of S. enterica subspecies enterica serovar Typhimurium (S. Typhimurium), a zoonotic serovar, on maize seed germination and plant growth. All the four strains of S. enterica subspecies enterica serovar Typhimurium significantly reduced germination of maize seeds in sprouting plates as well as in soil. About > or =2.7x10(3) Salmonella cfu ml(-1) of soaking water, while > or =2.7x10(7) Salmonella cfu g(-1) soil were required to significantly inhibit germination of maize. Similar inhibition of germination could be observed using > or = 16 mg of bacteria free Salmonella cell lysate (CL) protein per g of soil or > or =0.5 mg of CL protein per ml of soaking water in sprouting plates. At the constant dose of 3.6x10(7) to 3.8x10(7) Salmonella cfu or 5 mg cell lysate protein ml(-1) of soaking water, four strains of Salmonella significantly reduced germination, however difference between strains was insignificant. After germination too, maize growth was affected both by Salmonella organism and CL with little strain-to-strain variation. All Salmonella persisted in growing plants from 15 to 35 days of plant age and up to 190 days in soil. Maize plants once grown for a week in sterile soil were resistant to invasion of S. enterica subspecies enterica serovar Typhimurium in their leaves even in doses as high as 7.6x10(9) cfu g(-1) of soil. Salmonella persisted better and longer in plants grown from contaminated seed sown in loam soil, but rarely in plants grew in sandy soil. All maize plants had Salmonella in their stumps even after 35 days of sowing irrespective of kind of soil, primary source of infection (soil or seed) and type of S. enterica subspecies enterica serovar Typhimurium strain. The study revealed that Salmonella is not only zoonotic but a phytopathogen also.

Avirulent mutants of Macrophomina phaseolina and Aspergillus fumigatus initiate infection in Phaseolus mungo in the presence of phaseolinone; levamisole gives protection.

To evaluate the role of phaseolinone, a phytotoxin produced by Macrophomina phaseolina, in disease initiation, three nontoxigenic avirulent mutants of the fungus were generated by UV-mutagenesis. Two of them were able to initiate infection in germinating Phaseolus mungo seeds only in the presence of phaseolinone. The minimum dose of phaseoli-none required for infection in 30% seedlings was 2 5 mg/ml. A human pathogen, Aspergillus fumigatus was also able to infect germinating seeds of P. mungo in the presence of 5 mg/ml concentration of phaseolinone. Phaseolinone seemed to facilitate infection by A. fumigatus, which is not normally phytopathogenic, by reducing the immunity of germinating seedlings in a nonspecific way. Levamisole, a non-specific immunopotentiator gave protection against infection induced by A. fumigatus at an optimum dose of 50 mg/ml. Sodium malonate prevented the effects of levamisole.