938 resultados para sweet potato viruses


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Pós-graduação em Agronomia (Proteção de Plantas) - FCA

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Cassava is an important staple food for human and animal feeding in Cuba. Despite its importance, there is little or nonexistent information to diagnose preferences and frequency of consumption of cassava in that country. In this sense, the present article characterizes the preferences and frequency of consumption of cassava in the municipalities of Plaza de la Revolución-La Habana province, El Salvador–Guantanamo province and San José de Las Lajas–Mayabeque province in Cuba. A survey was conducted through a questionnaire containing twelve closed and two open questions. The sample was determined based on the number of total population of each municipality considering 95% as confidence interval and 5% as error margin. The results were statistically analyzed by calculating the absolute and the relative frequencies of each question. It was observed that the acquisition of cassava in the municipalities of Plaza de la Revolución, El Salvador and San José de las Lajas in Cuba is done by purchase small quantities of fresh cassava for home consumption within one week, due to the extreme perishability of cassava, which limits consumers' ability to store fresh roots at home. The choice of cassava is made based on both skin colour (light brown) and pulp (white) and empirical knowledge about its ease of cooking, and that cassava is mostly consumed in boiled and fried forms up to four times a week in times where there is root market supply with the desirable culinary characteristics (cooking facility), that is, from September to December.

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Sweet clover is adapted to practically all parts of Nebraska. It will grow under a wide range of soil and climatic conditions and is found growing wild in almost all sections of the state. It grows luxuriantly in eastern Nebraska and also does well in the western part of the state. Sweet clover will grow in regions of less rainfall than will red clover and, under certain conditions, it will do well where alfalfa is not easily grown. This 1923 circular is largely based on questionnaire replies received from more than 200 farmers growing sweet clover in all parts of the state and on personal observations of and experiences with the crop in various counties.

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Sweet clover has made a phenomenal growth in popularity and acreage during recent years. In Nebraska, the production increased from 30,000 acres in 1920 to 1,126,000 acres in 1930, an expansion of over one million acres in a 10-year period. Just a few years ago, when sweet clover was classified as a weed, it was the subject of proposed state legislation to prevent its production and spread. Today sweet clover has a recognized place among standard crops and in rotation systems. The acreage of sweet clover in Nebraska is now practically equal to that of alfalfa and is more than ten times that of red clover. Some Nebraska counties grow more than 40,000 acres of sweet clover annually. This 1932 extension circular discusses the kinds of sweet clover; time and method of seeding; kinds of seed and rates of seeding; liming and inoculation; growth habits; utilization of sweet clover for pasture, soil building, hay and seed; and sweet clover in wild hay meadows.

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Several large dsDNA-containing viruses such as poxviruses (smallpox) and herpes viruses are well known among the scientific community, as well as the general populace, because they cause human diseases. The large dsDNA insect-infecting baculoviruses are also well known in the scientific community because they are used both as biological control agents and as protein expression systems. However, there are other large dsDNA-containing viruses, including the giant 1.2-Mb mimivirus, which are less well known even though all of them play important roles in everyday life. Seven of these virus families are reviewed in this book.

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INFLUENZA A virus (IAV) (family Orthomyxoviridae) is a highly infectious respiratory pathogen of birds and mammals, including human beings and horses (Palese and Shaw 2007). The virus is classified into different subtypes based on the antigenic properties of the haemagglutinin (HA) and neuraminidase (NA) proteins. Sixteen HA subtypes (H1 to H16) and nine NA subtypes (N1 to N9) have been identified (Fouchier and others 2005). Two subtypes, H3N8 and H7N7, have been isolated from horses. The H7N7 subtype was first isolated from a horse in Czechoslovakia in 1956 (Prague/56) (Sovinova and others 1958), and the H3N8 subtype was first isolated from a horse in Miami, USA, in 1963 (Waddell and others 1963). The H7N7 subtype has not been isolated from horses for three decades and is presumed to be extinct (Webster 1993). The H3N8 subtype is currently a common cause of disease in horses worldwide. In horses, influenza is characterized by an abrupt onset of pyrexia, depression, coughing and nasal discharge, and is often complicated by secondary bacteria infections that can lead to pneumonia and death (Hannant and Mumford 1996). Although H3N8 is a major cause of morbidity in horses throughout the world, information on the seroprevalence of IAV in horses and other domestic animals in Mexico is limited.

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Sweet sorghum, a botanical variety of sorghum is a potential source of bioenergy because high sugar levels accumulate in its stalks. The objectives of this study were to explore the global diversity of sweet sorghum germplasm, and map the genomic regions that are associated with bioenergy traits. In assessing diversity, 142 sweet sorghum accessions were evaluated with three marker types (SSR, SRAP, and morphological markers) to determine the degree of relatedness among the accessions. The traits measured (anthesis date [AD], plant height [PH], biomass yield [BY], and moisture content [MC]) were all significantly different (P<0.05) among accessions. Morphological marker clustered the accessions into five groups based on PH, MC and AD. The three traits accounted for 92.5% of the variation. There were four and five groups based on SRAP and SSR data respectively classifying accessions mainly on their origin or breeding history. The observed difference between SSR and SRAP based clusters could be attributed to the difference in marker type. SSRs amplify any region of the genome whereas SRAP amplify the open reading frames and promoter regions. Comparing the three marker-type clusters, the markers complimented each other in grouping accessions and would be valuable in assisting breeders to select appropriate lines for crossing. In evaluating QTLs that are associated with bioenergy traits, 165 recombinant inbred lines (RILs) were planted at four environments in Nebraska. A genetic linkage map constructed spanned a length of 1541.3 cM, and generated 18 linkage groups that aligned to the 10 sorghum chromosomes. Fourteen QTLs (6 for brix, 3 for BY, 2 each for AD and MC, and 1 for PH) were mapped. QTLs for the traits that were significantly correlated, colocalized in two clusters on linkage group Sbi01b. Both parents contributed beneficial alleles for most of traits measured, supporting the transgressive segregation in this population. Additional work is needed on exploiting the usefulness of chromosome 1 in breeding sorghum for bioenergy.

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Huanglongbing (HLB) is associated with Candidatus Liberibacter spp., endogenous, sieve tube-restricted bacteria that are transmitted by citrus psyllid insect vectors. Transgenic expression in the phloem of specific genes that might affect Ca. Liberibacter spp. growth and development may be an adequate strategy to improve citrus resistance to HLB. To study specific phloem gene expression in citrus, we developed three different binary vector constructs with expression cassettes bearing the beta-glucuronidase (GUS) reporter gene (uidA) under the control of one of the three different promoters: Citrus phloem protein 2 (CsPP2), Arabidopsis thaliana phloem protein 2 (AtPP2), and Arabidopsis thaliana sucrose transporter 2 (AtSUC2). Transgenic lines of 'Hamlin', 'Pera', and 'Valencia' sweet oranges [Citrus sinensis (L.) Osbeck] were produced via Agrobacterium tumefaciens transformation. The epicotyl segments collected from in vitro germinated seedlings were used as explants. The gene nptII, which confers resistance to the antibiotic kanamycin, was used for selection. The transformation efficiency was expressed as the number of GUS-positive shoots over the total number of explants and varied from 1.54 to 6.08 % among the three cultivars and three constructs studied. Several lines of the three sweet orange cultivars analyzed using PCR and Southern blot analysis were genetically transformed with the three constructs evaluated. The histological GUS activity in the leaves indicates that the uidA gene was preferentially expressed in the phloem, which suggests that the use of the three promoters might be adequate for producing HLB-resistant transgenic sweet oranges. The results reported here conclusively demonstrate the preferential expression of GUS in the phloem driven by two heterologous and one homologous gene promoters. Key message The results reported here conclusively demonstrate the preferential expression of GUS in the phloem driven by two heterologous and one homologous gene promoters.

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An ecological life table for eggs and nymphs of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) was constructed with data obtained from orange orchards (Citrus sinensis Osbeck) in 2 regions of the State of Sao Paulo, over 4 generations in the period from XI-2006 to V-2007, comprising spring, summer, and fall seasons. Young growing shoots with D. citri eggs present were identified, and live individuals were counted until adult emergence. No predatory arthropods were observed in association with D. citri eggs and nymphs during the study. The mean parasitism of fourth- and fifth-instar nymphs by Tamarixia radiata Waterston (Hymenoptera: Eulophidae) was 2.3%. The durations of the egg-adult period were similar among the 4 generations, ranging from 18.0 to 24.7 d (at mean temperatures ranging from 21.6 to 26.0 degrees C) and followed the temperature requirement models obtained in the laboratory for D. citri. However, survival from the egg to the adult stage for the same period varied considerably from 1.7 to 21.4%; the highest mortalities were observed in the egg and small nymphal (first- to thirdinstar) stages, which were considered to be key phases for population growth of the pest.

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The euglossine bee Eulaema nigrita plays an important role for the pollination of native and economically important plants, such as the sweet passion-fruit Passiflora alata. E. nigrita uniquely collects the nectar from the flowers of P alata, nevertheless, it needs to visit other plants to collect pollen, nectar and other resources for its survival. There are two methods to identify the species of plants used by bees in their diet: by direct observation of the bees in the flowers, and through identification of pollen grains present in brood cells, feces, or in the bees' body. In order to identify the other plants that E. nigrita visits, we analyzed samples of pollen grains removed from the bee's body in the course of the flowering period of P alata. Among our results, the flora visited by E. nigrita comprised 40 species from 32 genera and 19 families, some of them used as a pollen source or just nectar. In spite of being a polyletic species, E. nigrita exhibited preference for some plant species with poricidal anthers. P alata which has high sugar concentration nectar was the main source of nectar for this bee in the studied area. Nonetheless, the pollinic analysis indicated that others nectariferous plant species are necessary to keep the populations of E. nigrita. Studies such as this one are important since they indicate supplementary pollen-nectar sources which must be used for the conservation of the populations of E. nigrita in crops neighbouring areas. In the absence of pollinators, growers are forced to pay for hand pollination, which increases production costs; keeping pollinators in cultivated areas is still more feasible to ensure sweet passion fruit production. Rev. Biol. Trop. 60 (4): 1553-1565. Epub 2012 December 01.

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Citrus Variegated Chlorosis (CVC) is currently present in approximately 40% of citrus plants in Brazil and causes an annual loss of around 120 million US dollars to the Brazilian citrus industry. Despite the fact that CVC has been present in Brazil for over 20 years, a relationship between disease intensity and yield loss has not been established. In order to achieve this, an experiment was carried out in a randomized block design in a 3 x 2 factorial scheme with 10-year-old Natal sweet orange. The following treatments were applied: irrigation with 0, 50 or 100% of the evapotranspiration of the crop, combined with natural infection or artificial inoculation with Xylella fastidiosa, the causal agent of CVC. The experiment was evaluated during three seasons. A negative exponential model was fitted to the relationships between yield versus CVC severity and yield versus Area Under Disease Progress Curve (AUDPC). In addition, the relationship between yield versus CVC severity and canopy volume was fitted by a multivariate exponential model. The use of the AUDPC variable showed practical limitations when compared with the variable CVC severity. The parameter values in the relationship of yieldCVC severity were similar for all treatments unlike in the multivariate model. Consequently, the yieldCVC intensity relationship (with 432 data points) could be described by one single model: y = 114.07 exp(-0.017 x), where y is yield (symptomless fruit weight in kg) and x is disease severity (R2 = 0.45; P < 0.01).

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The potato tuberworm Phthorimaea operculella (Zeller) is an important agricultural pest that causes significant economic losses to potato growers worldwide. The addition of an effective method of biological control for the potato tuberworm is greatly needed, and is currently unavailable in Brazil. The granulosis virus (Baculoviridae) is a promising biological control agent to protect post-harvest potatoes and in storage from the potato tuberworm. However, the control measure must be economically feasible. Liquid suspensions of a granulosis virus applied alone or in mixture with two commercial neem oil-based products (DalNeem (TM) and NeemAzal (TM)), and a dry powder formulation of viral granules were evaluated for control of potato tuberworm larvae by treating potato tubers under laboratory conditions. High larval mortality (86.7%) was achieved when DalNeem and virus were applied together at 4 mg of azadirachtin/L and 10(4) occlusion bodies (OBs)/mL, respectively. This combination resulted in a parts per thousand yen50% efficacy in relation to their counterparts alone. Conversely, NeemAzal did not enhance virus effectiveness against larvae of the potato tuberworm. The talc-based virus formulation was used for dusting seed tubers at different concentrations and resulted in 100% larval mortality at 5 x 10(8) OBs/g. Formulated and unformulated virus provided 50% mortality at 166 OBs/g and at 5.0 x 10(5) OBs/mL, respectively. As a result, talc-based virus formulation had a better control efficiency on potato tuberworm than the aqueous virus suspension. The granulosis virus combined with DalNeem at low rates or formulated with talc powder is a viable option to control the potato tuberworm under storage conditions.

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The present work aimed to investigate the effects of acute sucrose treatment on the perception of painful stimuli. Specifically, we sought to determine the involvement of the endogenous opioid peptide-mediated system as well as the role of the mu(1)-opioid receptor in antinociception organisation induced by acute sucrose intake. Nociception was assessed with the tail-flick test in rats (75, 150 and 250 g) of different ages acutely pre-treated with 500 mu L. of a sucrose solution (25, 50, 150 and 250 g/L) or tap water. Young and Adult rats (250 g) showed antinociception after treatment with 50 g/L (during 5 min) and 150 g/L and 250 g/L (during 20 min) sucrose solutions. Surprisingly, this antinociception was more consistent in mature adult rodents than in pups. To evaluate the role of opioid systems, mature adult rodents were pre-treated with different doses (0.25, 1 or 4mg/kg) of the non-selective opioid receptor antagonist naloxone, the selective pi-opioid receptor antagonist naloxonazine or vehicle followed by 250 g/L sucrose solution treatment. Sucrose-induced antinociception was reduced by pre-treatment with both naloxone and naloxonazine. The present findings suggest that sweet substance-induced hypo-analgesia is augmented by increasing sucrose concentrations in young and adult rodents. Acute oral sucrose treatment inhibits pain in laboratory animal by mediating endogenous opioid peptide and mu(1)-opioid receptor actions. (C) 2011 Elsevier Inc. All rights reserved.

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Protoplast fusion between sweet orange and mandarin/mandarin hybrids scion cultivars was performed following the model "diploid embryogenic callus protoplast + diploid mesophyll-derived protoplast". Protoplasts were isolated from embryogenic calli of 'Pera' and 'Westin' sweet orange cultivars (Citrus sinensis) and from young leaves of 'Fremont', Nules', and 'Thomas' mandarins (C. reticulata), and 'Nova' tangelo [C. reticulata x (C. paradisi x C. reticulata)]. The regenerated plants were characterized based on their leaf morphology (thickness), ploidy level, and simple sequence repeat (SSR) molecular markers. Plants were successfully generated only when 'Pera' sweet orange was used as the embryogenic parent. Fifteen plants were regenerated being 7 tetraploid and 8 diploid. Based on SSR molecular markers analyses all 7 tetraploid regenerated plants revealed to be allotetraploids (somatic hybrids), including 2 from the combination of 'Pera' sweet orange + 'Fremont' mandarin, 3 'Pera' sweet orange + 'Nules' mandarin, and 2 'Pera' sweet orange + 'Nova' tangelo, and all the diploid regenerated plants showed the 'Pera' sweet orange marker profile. Somatic hybrids were inoculated with Alternaria alternata and no disease symptoms were detected 96 h post-inoculation. This hybrid material has the potential to be used as a tetraploid parent in interploid crosses for citrus scion breeding.