Regeneração de Passiflora suberosa em suspensão celular.

O gênero Passiflora é o maior e o mais importante da família Passifloraceae por abrigar as principais espécies exploradas comercialmente no mundo. Muitas espécies são cultivadas para a produção de sucos, consumo in natura, extração de substâncias de interesse farmacológico e fins ornamentais, mas a presença de patógenos de solo que vêm dizimando os cultivos. Uma alternativa é a hibridação interespecífica, ou seja, cruzamentos convencionais, de seleção ou cultivares comerciais, com as espécies silvestres na produção de porta-enxertos resistentes, porém esses híbridos sexuais quando obtidos têm apresentado baixa fertilidade. Desta forma, uma alternativa viável é a produção de porta-enxertos tetraplóides com genes de resistência aos patógenos pela técnica da hibridação somática. Contudo, para isto são necessários protocolos eficientes de regeneração das espécies parentais diplóides a patir de células individuais. Assim, o objetivo desse trabalho foi estabelecer um protocolo de regeneração de plantas a partir de células em suspensão da espécie de P. suberosa. Para tanto, calos MR13 BIO oriundos da Embrapa de Mandioca e Fruticultura Tropical de Cruz das Almas/BA foram submetidos ao meio de cultura MS (Murashige e Skoog) suplementado com os reguladores de crescimento BAP 1,0 mg/L ou 2,0 mg/L; KIN 1,0 mg/L ou 2,0 mg/L para a obtenção de calos friáveis no Laboratório de Cultura de Tecidos Vegetais da unidade experimental Horto Florestal da Universidade Estadual de Feira de Santana/BA. O melhor resultado, BAP 2,0 mg/L, foi submetido aos testes contendo balanço de fitorreguladores: MS + BAP 2,0 mg/L + ANA 0,5 mg/L + Kin 1,0 mg/L ou MS + AIA 2,5 mg/L + ANA 0,5 mg/L +Kin 1,0 mg/L, suplementado com agar 6% e, ao teste de culturas de células em suspensão, na ausência de luz, em meio MS na metade da concentração dos sais, suplementados pelos compostos orgânicos (extrato de malte ou extrato de levedura) e mantidos sob 140 rpm de agitação contínua num volume final de 100 mL em frascos erlenmeyers de 250 mL de capacidade. As células colocadas em suspensão no meio líquido suplementado com extrato de malte foram capazes de regenerar de plantas inteiras de P. suberosa, a partir de células diplóides, num prazo de 60 dias na ausência de luz.Disponível em: Acesso em: 02 mar. 201

Fontes de resistência de videira ao fungo oídio no Nordeste brasileiro.

Foram avaliadas 135 variedades distintas em três ciclos, observando-se as mesmas plantas sem nenhum oídicida

In Vitro Propagation of \u3ci\u3ePennisetum purpureum\u3c/i\u3e Schum.

A protocol is described for rapid multiplication of elephantgrass (Pennisetum purpureum Schum.) through shoot tip culture. The plant growth medium consisted of basal medium of Murashige and Skoog (MS) and vitamins Wood Plant Medium (WPM). The medium was supplemented with 0.00; 4.44; 8.88; 13.32 and 17.76 μM of benzylaminopurine (BAP). The elephantgrass was micropropagated by axillary shoot proliferations. Maximum propagule proliferation occurred on Murashige and Skoog (MS) medium enriched with 4.4 μM benzylaminopurine (BAP), resulting an average of 4.0 shoots per explant from cultivar Mineiro and 2.19 from cultivar Pioneiro. The best height and root plantlets were obtained with medium without growth regulator after 28 days

Seleção molecular assistida para identificação de alelo para cor rósea na cultivar Brisa IPA 12.

O objetivo do presente trabalho foi aplicar os marcadores moleculares ANS para genotipar 270 plantas da Brisa IPA 12 que segregavam para bulbos de cor rósea, que podem ficar ?escondidos? nas plantas heterozigotas, de forma a eliminar essa condição que dificulta a aceitação comercial dessa cultivar de cebola. DNA total foi extraído conforme protocolo CTAB 2x, de amostras foliares de plantas coletadas aos 30 dias após a semeadura dos bulbos vernalizados e pré-selecionados para a cor amarelaSuplemento. Edição dos Anais do 53 Congresso Brasileiro de Olericultura, jul. 2014

Satellite DNA in Paphiopedilum subgenus Parvisepalum as revealed by high-throughput sequencing and fluorescent in situ hybridization

Background: Satellite DNA is a rapidly diverging, largely repetitive DNA component of many eukaryotic genomes. Here we analyse the evolutionary dynamics of a satellite DNA repeat in the genomes of a group of Asian subtropical lady slipper orchids (Paphiopedilum subgenus Parvisepalum and representative species in the other subgenera/sections across the genus). A new satellite repeat in Paphiopedilum subgenus Parvisepalum, SatA, was identified and characterized using the RepeatExplorer pipeline in HiSeq Illumina reads from P. armeniacum (2n = 26). Reconstructed monomers were used to design a satellite-specific fluorescent in situ hybridization (FISH) probe. The data were also analysed within a phylogenetic framework built using the internal transcribed spacer (ITS) sequences of 45S nuclear ribosomal DNA. Results: SatA comprises c. 14.5% of the P. armeniacum genome and is specific to subgenus Parvisepalum. It is composed of four primary monomers that range from 230 to 359 bp and contains multiple inverted repeat regions with hairpin loop motifs. A new karyotype of P. vietnamense (2n = 28) is presented and shows that the chromosome number in subgenus Parvisepalum is not conserved at 2n = 26, as previously reported. The physical locations of SatA sequences were visualised on the chromosomes of all seven Paphiopedilum species of subgenus Parvisepalum (2n = 26–28), together with the 5S and 45S rDNA loci using FISH. The SatA repeats were predominantly localisedin the centromeric, peri-centromeric and sub-telocentric chromosome regions, but the exact distribution pattern was species-specific. Conclusions: We conclude that the newly discovered, highly abundant and rapidly evolving satellite sequence SatA is specific to Paphiopedilum subgenus Parvisepalum. SatA and rDNA chromosomal distributions are characteristic of species, and comparisons between species reveal that the distribution patterns generate a strong phylogenetic signal. We also conclude that the ancestral chromosome number of subgenus Parvisepalum and indeed of all Paphiopedilum could be either 2n = 26 or 28, if P. vietnamense is sister to all species in the subgenus as suggested by the ITS data

Orthorhombic Phase of Crystalline Polyethylene: A Constant Pressure Path Integral Monte Carlo Study

In this paper we present a Path Integral Monte Carlo (PIMC) simulation of the orthorhombic phase of crystalline polyethylene, using an explicit atom force field with unconstrained bond lengths and angles. This work represents a quantum extension of our recent classical simulation (J. Chem. Phys. 106, 8918 (1997)). It is aimed both at exploring the applicability of the PIMC method on such polymer crystal systems, as well as on a detailed assessment of the importance of quantum effects on different quantities. We used the $NpT$ ensemble and simulated the system at zero pressure in the temperature range 25 - 300 K, using Trotter numbers between 12 and 144. In order to investigate finite-size effects, we used chains of two different lengths, C_12 and C_24, corresponding to the total number of atoms in the super-cell being 432 and 864, respectively. We show here the results for structural parameters, like the orthorhombic lattice constants a,b,c, and also fluctuations of internal parameters of the chains, such as bond lengths and bond and torsional angles. We have also determined the internal energy and diagonal elastic constants c_11, c_22 and c_33. We discuss the temperature dependence of the measured quantities and compare to that obtained from the classical simulation. For some quantities, we discuss the way they are related to the torsional angle fluctuation. In case of the lattice parameters we compare our results to those obtained from other theoretical approaches as well as to some available experimental data. In order to study isotope effects, we simulated also a deuterated polyethylene crystal at a low temperature. We also suggest possible ways of extending this study and present some general considerations concerning modeling of polymer crystals.Comment: 18 pages, RevTex, 18 figures, 3 tables, submitted to Phys. Rev.

Influence of a knot on the strength of a polymer strand

Many experiments have been done to determine the relative strength of different knots, and these show that the break in a knotted rope almost invariably occurs at a point just outside the `entrance' to the knot. The influence of knots on the properties of polymers has become of great interest, in part because of their effect on mechanical properties. Knot theory applied to the topology of macromolecules indicates that the simple trefoil or `overhand' knot is likely to be present with high probability in any long polymer strand. Fragments of DNA have been observed to contain such knots in experiments and computer simulations. Here we use {\it ab initio} computational methods to investigate the effect of a trefoil knot on the breaking strength of a polymer strand. We find that the knot weakens the strand significantly, and that, like a knotted rope, it breaks under tension at the entrance to the knot.Comment: 3 pages, 4 figure

Efeito da inoculação de Xanthomonas campestris pv. viticola em plantas de neem.

Suplemento. Edição dos resumos do XXXIX Congresso Brasileiro de Fitopatologia, Salvador, ago. 2006

Techniques for Arbuscular Mycorrhiza Inoculum Reduction

It is well established that arbuscular mycorrhizal (AM) fungi can play a significant role in sustainable crop production and environmental conservation. With the increasing awareness of the ecological significance of mycorrhizas and their diversity, research needs to be directed away from simple records of their occurrence or casual speculation of their function (Smith and Read 1997). Rather, the need is for empirical studies and investigations of the quantitative aspects of the distribution of different types and their contribution to the function of ecosystems. There is no such thing as a fungal effect or a plant effect, but there is an interaction between both symbionts. This results from the AM fungi and plant community size and structure, soil and climatic conditions, and the interplay between all these factors (Kahiluoto et al. 2000). Consequently, it is readily understood that it is the problems associated with methodology that limit our understanding of the functioning and effects of AM fungi within field communities. Given the ubiquous presence of AM fungi, a major constraint to the evaluation of the activity of AM colonisation has been the need to account for the indigenous soil native inoculum. This has to be controlled (i.e. reduced or eliminated) if we are to obtain a true control treatment for analysis of arbuscular mycorrhizas in natural substrates. There are various procedures possible for achieving such an objective, and the purpose of this chapter is to provide details of a number of techniques and present some evaluation of their advantages and disadvantages. Although there have been a large number of experiments to investigated the effectiveness of different sterilization procedures for reducing pathogenic soil fungi, little information is available on their impact on beneficial organisms such as AM fungi. Furthermore, some of the techniques have been shown to affect physical and chemical soil characteristics as well as eliminate soil microorganisms that can interfere with the development of mycorrhizas, and this creates difficulties in the interpretation of results simply in terms of possible mycorrhizal activity. An important subject is the differentiation of methods that involve sterilization from those focussed on indigenous inoculum reduction. Soil sterilization aims to destroy or eliminate microbial cells while maintaining the existing chemical and physical characteristics of the soil (Wolf and Skipper 1994). Consequently, it is often used for experiments focussed on specific AM fungi, or to establish a negative control in some other types of study. In contrast, the purpose of inoculum reduction techniques is to create a perturbation that will interfere with mycorrhizal formation, although not necessarily eliminating any component group within the inoculum. Such an approach allows the establishment of different degrees of mycorrhizal formation between treatments and the study of relative effects. Frequently the basic techniques used to achieve complete sterilization or just an inoculum reduction may be similar but the desired outcome is accomplished by adjustments of the dosage or intensity of the treatment. The ultimate choice of methodology for establishing an adequate non-mycorrhizal control depends on the design of the particular experiments, the facilities available and the amount of soil requiring treatment

Agronomic Management of Indigenous Mycorrhizas

Many of the advantages conferred to plants by arbuscular mycorrhiza (AM) are associated to the ability of AM plants to explore a greater volume of soil through the extraradical mycelium. Sieverding (1991) estimates that for each centimetre of colonized root there is an increase of 15 cm3 on the volume of soil explored, this value can increase to 200 cm3 depending on the circumstances. Due to the enhancement of the volume of soil explored and the ability of the extraradical mycelium to absorb and translocate nutrients to the plant, one of the most obvious and important advantages resulting from mycorrhization is the uptake of nutrients. Among of which the ones that have immobilized forms in soil, such as P, assume particular significance. Besides this, many other benefits are recognized for AM plants (Gupta et al, 2000): water stress alleviation (Augé, 2004; Cho et al, 2006), protection from root pathogens (Graham, 2001), tolerance to toxic heavy metals and phytoremediation (Audet and Charest, 2006; Göhre and Paszkowski, 2006), tolerance to adverse conditions such as very high or low temperature, high salinity (Sannazzaro et al, 2006), high or low pH (Yano and Takaki, 2005) or better performance during transplantation shock (Subhan et al, 1998). The extraradical hyphae also stabilize soil aggregates by both enmeshing soil particles (Miller e Jastrow, 1992) and producing a glycoprotein, golmalin, which may act as a glue-like substance to adhere soil particles together (Wright and Upadhyaya, 1998). Despite the ubiquous distribution of mycorrhizal fungi (Smith and Read, 2000) and only a relative specificity between host plants and fungal isolates (McGonigle and Fitter, 1990), the obligate nature of the symbiosis implies the establishment of a plant propagation system, either under greenhouse conditions or in vitro laboratory propagation. These techniques result in high inoculum production costs, which still remains a serious problem since they are not competitive with production costs of phosphorus fertilizer. Even if farmers understand the significance of sustainable agricultural systems, the reduction of phosphorus inputs by using AM fungal inocula alone cannot be justified except, perhaps, in the case of high value crops (Saioto and Marumoto, 2002). Nurseries, high income horticulture farmers and no-agricultural application such as rehabilitation of degraded or devegetated landscapes are examples of areas where the use of commercial inoculum is current. Another serious problem is quality of commercial available products concerning guarantee of phatogene free content, storage conditions, most effective application methods and what types to use. Besides the information provided by suppliers about its inoculum can be deceiving, as from the usually referred total counts, only a fraction may be effective for a particular plant or in specific soil conditions. Gianinazzi and Vosátka (2004) assume that progress should be made towards registration procedures that stimulate the development of the mycorrhizal industry. Some on-farm inoculum production and application methods have been studied, allowing farmers to produce locally adapted isolates and generate a taxonomically diverse inoculum (Mohandas et al, 2004; Douds et al, 2005). However the inocula produced this way are not readily processed for mechanical application to the fields, being an obstacle to the utilization in large scale agriculture, especially row crops, moreover it would represent an additional mechanical operation with the corresponding economic and soil compaction costs. It is well recognized that inoculation of AM fungi has a potential significance in not only sustainable crop production, but also environmental conservation. However, the status quo of inoculation is far from practical technology that can be widely used in the field. Together a further basic understanding of the biology and diversity of AM fungi is needed (Abbott at al, 1995; Saito and Marumoto, 2002). Advances in ecology during the past decade have led to a much more detailed understanding of the potential negative consequences of species introductions and the potential for negative ecological consequences of invasions by mycorrhizal fungi is poorly understood. Schwartz et al, (2006) recommend that a careful assessment documenting the need for inoculation, and the likelihood of success, should be conducted prior to inoculation because inoculations are not universally beneficial. Agricultural practices such as crop rotation, tillage, weed control and fertilizer apllication all produce changes in the chemical, physical and biological soil variables and affect the ecological niches available for occupancy by the soil biota, influencing in different ways the symbiosis performance and consequently the inoculum development, shaping changes and upset balance of native populations. The molecular biology tools developed in the latest years have been very important for our perception of these changes, ensuing awareness of management choice implications in AM development. In this context, for extensive farming systems and regarding environmental and economic costs, the identification of agronomic management practices that allow controlled manipulation of the fungal community and capitalization of AM mutualistic effect making use of local inoculum, seem to be a wise option for mycorrhiza promotion and development of sustainable crop production