Evaluation of Leaf Spot Resistance in Wild \u3ci\u3eArachis\u3c/i\u3e Species of Section \u3ci\u3eArachis\u3c/i\u3e

Wild diploid Arachis species are potential sources of resistance to early (ELS) and late (LLS) leaf spot diseases caused by Passalora arachidicola (syn. Cercospora arachidicola Hori), and Nothopassalora personata (syn. Cercosporidium personatum (Berk. & Curt.) Deighton), respectively. Within section Arachis, limited information is available on the extent of genetic variation for resistance to these fungal pathogens. A collection of 78 accessions representing 15 wild species of Arachis section Arachis from the U.S peanut germplasm collection was evaluated for resistance to leaf spots. Screening was conducted under field (natural inoculum) conditions in Dawson, Georgia, during 2017 and 2018. Accessions differed significantly (P , 0.01) for all three disease variables evaluated, which included final defoliation rating, ELS lesion counts, and LLS lesion counts. Relatively high levels of resistance were identified for both diseases, with LLS being the predominant pathogen during the two years of evaluation. This research documents new sources of resistance to leaf spot diseases selected from an environment with high inoculum pressure. The presence of ELS and LLS enabled the selection of resistant germplasm for further introgression and pre-breeding

Communication: Molecular-level insights into asymmetric triblock copolymers: Network and phase development

Copyright (2014) AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Journal of Chemical Physics (Communication) 141 and may be found at http://dx.doi.org/10.1063/1.4896612Molecularly asymmetric triblock copolymers progressively grown from a parent diblock copolymer can be used to elucidate the phase and property transformation from diblock to network-forming triblock copolymer. In this study, we use several theoretical formalisms and simulation methods to examine the molecular-level characteristics accompanying this transformation, and show that reported macroscopic-level transitions correspond to the onset of an equilibrium network. Midblock conformational fractions and copolymer morphologies are provided as functions of copolymer composition and temperature.Nonwovens Institute at North Carolina State University and the Polish Ministry of Science and Higher Education (Grant No. N204 125039)

Relationships of the wild peanut species, section Arachis: a resource for botanical classification, crop improvement, and germplasm management.

Premise Wild species are strategic sources of valuable traits to be introduced into crops through hybridization. For peanut, the 33 currently described wild species in the section Arachis are particularly important because of their sexual compatibility with the domesticated species, Arachis hypogaea. Although numerous wild accessions are carefully preserved in seed banks, their morphological similarities pose challenges to routine classification. Methods Using a high-density array, we genotyped 272 accessions encompassing all diploid species in section Arachis. Detailed relationships between accessions and species were revealed through phylogenetic analyses and interpreted using the expertise of germplasm collectors and curators. Results Two main groups were identified: one with A genome species and the other with B, D, F, G, and K genomes. Species groupings generally showed clear boundaries. Structure within groups was informative, for instance, revealing the history of the proto-domesticate A. stenosperma. However, some groupings suggested multiple sibling species. Others were polyphyletic, indicating the need for taxonomic revision. Annual species were better defined than perennial ones, revealing limitations in applying classical and phylogenetic species concepts to the genus. We suggest new species assignments for several accessions. Conclusions Curated by germplasm collectors and curators, this analysis of species relationships lays the foundation for future species descriptions, classification of unknown accessions, and germplasm use for peanut improvement. It supports the conservation and curation of current germplasm, both critical tasks considering the threats to the genus posed by habitat loss and the current restrictions on new collections and germplasm transfer

Analytical protocols for separation and electron microscopy of nanoparticles interacting with bacterial cells

An important step toward understanding interactions between nanoparticles (NPs) and bacteria is the ability to directly observe NPs interacting with bacterial cells. NPbacteria mixtures typical in nanomedicine, however, are not yet amendable for direct imaging in solution. Instead, evidence of NPcell interactions must be preserved in derivative (usually dried) samples to be subsequently revealed in high-resolution images, e.g., via scanning electron microscopy (SEM). Here, this concept is realized for a mixed suspension of model NPs and Staphylococcus aureus bacteria. First, protocols for analyzing the relative colloidal stabilities of NPs and bacteria are developed and validated based on systematic centrifugation and comparison of colony forming unit (CFU) counting and optical density (OD) measurements. Rate-dependence of centrifugation efficiency for each component suggests differential sedimentation at a specific predicted rate as an effective method for removing free NPs after co-incubation; the remaining fraction comprises bacteria with any associated NPs and can be examined, e.g., by SEM, for evidence of NPbacteria interactions. These analytical protocols, validated by systematic control experiments and high-resolution SEM imaging, should be generally applicable for investigating NPbacteria interactions.financial support from the following sources: grant SFRH/BPD/47693/2008 from the Portuguese Foundation for Science and Technology (FCT); FCT Strategic Project PEst-OE/EQB/LA0023/2013; project “BioHealth Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124-FEDER-000027, cofunded by the Programa Operacional Regional do Norte (ON.2−O Novo Norte), QREN, FEDER; project “Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB”, ref. FCOMP-01-0124-FEDER- 027462

Hollow mesoporous silica nanoparticles for intracellular delivery of fluorescent dye

In this study, hollow mesoporous silica nanoparticles (HMSNs) were synthesized using the sol-gel/emulsion approach and its potential application in drug delivery was assessed. The HMSNs were characterized, by transmission electron microscopy (TEM), Scanning Electron Microscopy (SEM), nitrogen adsorption/desorption and Brunauer-Emmett-Teller (BET), to have a mesoporous layer on its surface, with an average pore diameter of about 2 nm and a surface area of 880 m2/g. Fluorescein isothiocyanate (FITC) loaded into these HMSNs was used as a model platform to assess its efficacy as a drug delivery tool. Its release kinetic study revealed a sequential release of FITC from the HMSNs for over a period of one week when soaked in inorganic solution, while a burst release kinetic of the dye was observed just within a few hours of soaking in organic solution. These FITC-loaded HMSNs was also found capable to be internalized by live human cervical cancer cells (HeLa), wherein it was quickly released into the cytoplasm within a short period of time after intracellular uptake. We envision that these HMSNs, with large pores and high efficacy to adsorb chemicals such as the fluorescent dye FITC, could serve as a delivery vehicle for controlled release of chemicals administered into live cells, opening potential to a diverse range of applications including drug storage and release as well as metabolic manipulation of cells

Biology, speciation and utilization of peanut species

Peanut, also known as groundnut (Arachis hypogaea L.), is a native new world crop. Arachis species originated in South America and are found in tropical and subtropical areas. Eighty-one species have been named (Krapovickas and Gregory, 1994; Valls and Simpson, 2005; Valls et al., 2013), including the domesticated peanut, A. hypogaea L. Species have evolved in highly diverse habitats and both annual and perennial types exist. New species are being discovered in areas that previously were very difficult to reach because of poor roads and transportation. It is likely that the genus originated in the highlands in the southwestern Mato Grosso do Sul region of Brazil close to Gran Pantanal where the most ancient species of the genus (Arachis guaranitica Chodat. and Hassl. and Arachis tuberosa Bong. Ex Benth.) are found (Gregory et al., 1980; Simpson and Faries, 2001). Subsequently, as the planalto continued to be uplifted coupled with water flow, the genus spread into the drier lowlands of South America (Gregory and Gregory, 1979; Stalker and Simpson, 1995; Simpson et al., 2001). The genus likely originated in tropical wetland areas and subsequently adapted for survival in dry environments. Species in the genus Arachis are widely distributed in South America from Northeast Brazil to southern Uruguay and from the Andean lowlands in the west to the eastern Atlantic coast, and the distribution is continuous across this region (Valls et al., 1985). Species grow in deep friable sand to thick, gummy clay and on schist rocks with virtually no soil, suggesting that species have adapted to highly diverse and harsh environments (Simpson et al., 2001). Fruiting below ground likely protected the seeds from predators and the many root adaptations (e.g., rhizomes, tuberous roots) likely helped species to adapt to new habitats. Conversely, the geocarpic fruit impeded rapid spread into new environments. Krapovickas and Gregory (1994) indicated that the most defining morphological features of the genus are underground plant parts, including the fruits, rhizomatous structures, root systems, and hypocotyls. The center of origin for the cultivated species A. hypogaea is believed to be southern Bolivia to northwestern Argentina based on the occurrence of the two progenitor species Arachis duranensis and Arachis ipaënsis, and archaeological evidence gathered in this region (Hammons, 1982; Stalker and Simpson, 1995). Simpson et al. (2001) also suggested that the eastern slopes of Cordillera may be a possible area for origin of A. hypogaea because of the favorable environment for peanut growth. Advances in the peanut genome sequence and the availability of new genomic tools will help clarify the origin and evolution of the cultivated and wild species of the genus Arachis. Wild peanut species were important as sources of food in pre-Columbian times and several taxa are still widely used as forages or for their aesthetic value as a ground cover. Arachis glabrata and Arachis pintoi are utilized for grazing and Arachis repens is used as a ground cover in residential areas and roadsides in tropical regions (Mathews et al., 2000; Hernandez-Garay et al., 2004). Two wild species (Arachis villosulicarpa Hoehne and Arachis stenosperma Krapov. and W.C. Gregory) were cultivated by indigenous people in Brazil for food and medicinal use, albeit on a limited scale (Gregory et al., 1973; Simpson et al., 2001), but only A. hypogaea is economically important today as a human food source. Importantly, many Arachis species have extremely high levels of disease and insect resistances that are not present in cultivated peanut.Fil: Stalker, H. Thomas. North Carolina State University; Estados UnidosFil: Tallury, Shyamalrau P.. Clemson University,; Estados UnidosFil: Seijo, José Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Leal Bertioli, Soraya C.M.. Embrapa Agroindustrial Tropical - CNPAT; Brasi

Biology, speciation, and utilization of peanut species

Peanut, also known as groundnut (Arachis hypogaea L.), is a native new world crop. Arachis species originated in South America and are found in tropical and subtropical areas. Eighty-one species have been named (Krapovickas and Gregory, 1994; Valls and Simpson, 2005; Valls et al., 2013), including the domesticated peanut, A. hypogaea L. Species have evolved in highly diverse habitats and both annual and perennial types exist. New species are being discovered in areas that previously were very difficult to reach because of poor roads and transportation. It is likely that the genus originated in the highlands in the southwestern Mato Grosso do Sul region of Brazil close to Gran Pantanal where the most ancient species of the genus (Arachis guaranitica Chodat. and Hassl. and Arachis tuberosa Bong. Ex Benth.) are found (Gregory et al., 1980; Simpson and Faries, 2001). Subsequently, as the planalto continued to be uplifted coupled with water flow, the genus spread into the drier lowlands of South America (Gregory and Gregory, 1979; Stalker and Simpson, 1995; Simpson et al., 2001). The genus likely originated in tropical wetland areas and subsequently adapted for survival in dry environments