The effects of nitrogen and potassium nutrition on the growth of nonembryogenic and embryogenic tissue of sweet orange (Citrus sinensis (L.) Osbeck)

<p>Abstract</p> <p>Background</p> <p>Mineral nutrients are one of the most basic components of plant tissue culture media. Nitrogen in the form of NH₄⁺and NO₃^-is the dominant mineral nutrient in most plant tissue culture formulations, with effects dependent on both the proportion and the amount of NH₄⁺and NO₃^-. The effects of nitrogen nutrition on the growth of nonembryogenic and embryogenic cell lines of sweet orange (<it>C. sinensis </it>(L.) Osbeck cv. 'Valencia'), tissues routinely used in citrus horticultural and plant improvement research, was explored using an experimental approach free of ion confounding that included a 2-component mixture (NH₄⁺:K⁺) and a quantitative factor [NO₃^-] crossed by the mixture, thereby providing ion-specific estimates of proportional and amount effects.</p> <p>Results</p> <p>First, the linear mixture component, though only a comparison of the design space vertices, was highly significant for both tissue types and showed that NH₄⁺was required by both tissues. Second, the NH₄⁺* K⁺mixture term was highly significant for both tissue types, revealing that NH₄⁺and K⁺exhibit strong synergistic blending and showed that growth was substantially greater at certain blends of these two ions. Third, though the interaction between the NH₄⁺:K⁺mixture and NO₃^-amount on fresh weight accumulation for both tissue types was significant, it was substantially less than the main effect of the NH₄⁺:K⁺mixture. Fourth, a region of the design space was identified where fresh weight growth was increased 198% and 67% over the MS medium controls for nonembryogenic and embryogenic tissues.</p> <p>Conclusion</p> <p>By designing a mineral nutrient experiment free of ion confounding, a direct estimation of ion-specific proportional and amount effects on plant tissue growth is possible. When the ions themselves are the independent factors and/or mixture components, the resulting design space can be systematically explored to identify regions where the response(s) is substantially improved over current media formulations. In addition, because the response is over a defined experimental region, a specific medium formulation is more accurately interpreted as a coordinate in the specified design geometry.</p

Nivel de ploidía y composición genómica de accesiones de Musa spp. en la colección del USDA-ARS Tropical Agriculture Research Station

Plant germplasm collections serve as repositories for important genes. However, insufficient and inaccurate characterization of the genetic diversity in a collection can slow or can prevent full utilization of genetic resources. Bananas and plantains (Musa spp., Colla) are some of the most important food crops in the world. Germplasm characterization efforts in Musa have focused mostly on agronomic and morphological traits although with the advent of molecular markers genotypic characterization efforts are increasing. Genomic composition in Musa is based on a plant's ploidy level and on whether it is of a hybrid origin. Genomic compositions of Musa spp. have been associated with disease and insect resistance, production and flavor characteristics. The Musa spp. collection of the USDA-ARS Tropical Agriculture Research Station consists of 135 accessions, many of which are of unknown genomic composition. In an effort to better characterize the collection, RAPD and PCR-RFLP markers, as well as flow cytometry, were employed to determine genomic composition and ploidy level. Plant accessions maintained in the collection belong to several Musa species and their hybrids with different ploidy levels. In addition, several differences in ploidy as well as genomic composition were identified when comparing findings in this study to those reported in the literature.Los bancos de germoplasma sirven como fuente de genes importantes. Sin embargo, la falta de caracterización o caracterización inexacta de la diversidad dentro de una colección reduce y puede prevenir el uso máximo de los recursos genéticos. Los guineos y plátanos (Musa spp., Colla.) son algunos de los cultivos más importantes como fuente alimenticia en el mundo. La mayoría de los esfuerzos para la caracterización en el género Musa se han enfocado especialmente en rasgos agronómicos y fenotípicos, pero con el desarrollo de técnicas moleculares la caracterización genotípica está progresando. La composición genómica en Musa se basa en el nivel de ploidía como también en si es de origen híbrido. Las diferentes composiciones genómicas se asocian con ciertas características como son la resistencia a insectos y patógenos, la producción y el sabor. La colección de Musa spp. de la Estación de Investigación de Agricultura Tropical del USDA-ARS consiste de 135 accesiones, de las cuales solo a un porcentaje bajo se les conoce la composición genómica exacta. En un esfuerzo por caracterizar mejor la colección se utilizaron las técnicas de RAPDs y PCR-RFLPs al igual que citometría de flujo para determinar la composición genómica. Las plantas de la colección pertenecen a varias especies de Musa y a sus híbridos, y tienen ploidía variada. Además, se encontraron diferencias en ploidía así como en composición genómica cuando se compararon los resultados de este estudio con aquellos resultados reportados en la literatura

Mapping the Fundamental Niches of Two Freshwater Microalgae, Chlorella vulgaris

The fundamental niche defined by five ions, NO3 −, PO4 3−, K+, Na+, and Cl−, was mapped for Chlorella vulgaris (Trebouxiophyceae) and Peridinium cinctum (Dinophyceae) growth rates and maximum cell densities in batch cultures. A five dimensional ion-mixture experimental design was projected across a total ion concentration gradient of 1 to 30 mM to delineate the ion-based, “potential” niche space, defined as the entire n-dimensional hypervolume demarcated by the feasible ranges of the independent factors under consideration. The growth rate-based, fundamental niche volumes overlapped for ca. 94% of the ion mixtures, although the regions of maximal growth rates and cell densities were different for each alga. Both C. vulgaris and P. cinctum exhibited similar positive responses to cations and negative responses to anions. It was determined that total ion concentration for these five ions, from 1 to 30 mM, did not directly affect either growth rate or maximal cell density for either alga, although it did play an interactive role with several ions. This study is the first that we are aware of to attempt the mapping of a multivariate, ion-based, fundamental niche volume. The implications of the experimental design utilized and the potential utility of this type of approach are discussed

Latent Period and Transmission of “Candidatus Liberibacter solanacearum” by the Potato Psyllid Bactericera cockerelli (Hemiptera: Triozidae)

"Candidatus Liberibacter solanacearum" (Lso) is an economically important pathogen of solanaceous crops and the putative causal agent of zebra chip disease of potato (Solanum tuberosum L.). This pathogen is transmitted to solanaceous species by the potato psyllid, Bactericera cockerelli (Šulc), but many aspects of the acquisition and transmission processes have yet to be elucidated. The present study was conducted to assess the interacting effects of acquisition access period, incubation period, and host plant on Lso titer in psyllids, the movement of Lso from the alimentary canal to the salivary glands of the insect, and the ability of psyllids to transmit Lso to non-infected host plants. Following initial pathogen acquisition, the probability of Lso presence in the alimentary canal remained constant from 0 to 3 weeks, but the probability of Lso being present in the salivary glands increased with increasing incubation period. Lso copy numbers in psyllids peaked two weeks after the initial pathogen acquisition and psyllids were capable of transmitting Lso to non-infected host plants only after a two-week incubation period. Psyllid infectivity was associated with colonization of insect salivary glands by Lso and with Lso copy numbers >10,000 per psyllid. Results of our study indicate that Lso requires a two-week latent period in potato psyllids and suggest that acquisition and transmission of Lso by psyllids follows a pattern consistent with a propagative, circulative, and persistent mode of transmission

Synthetic Ligands of Olfactory Binding Proteins Modulate Aggregation Response of Asian Citrus Psyllid in the Presence of Host-Plant Volatiles

There is interest in using ligands of chemosensory binding proteins (CBP) to augment an insect’s responsiveness to chemosensory cues. We showed previously that combining a synthetic ligand of a CBP with limonene, a common citrus volatile, enhanced the probing response of Asian citrus psyllid (Diaphorinacitri). Here, we determined whether synthetic compounds, which were ligands of D. citri olfactory binding protein (OBP) DCSAP4, influenced the settling and aggregation levels of psyllids on young citrus shoots. The test ligands and Cmac scent were dispensed from a droplet of an emulsified wax product (SPLAT) placed on the bottom of each vial. The shoots were presented: (1) alone (shoot + blank SPLAT), (2) with a mixture of citrus volatiles (“Cmac scent”) (shoot + SPLAT with Cmac scent), or (3) with different concentrations of test ligands (shoot + SPLAT with test ligand at concentration 1, shoot + SPLAT with test ligand at concentration 2, etc.). Depending on the availability of test ligands, sprigs, and psyllids, each test included from two to four replicates of each treatment (i.e., shoot only, shoot + Cmac scent, shoot + test ligand at concentration 1, shoot + test ligand at concentration 2, etc.); only a single test ligand was presented in each test. For each test, 200 D. citri were released in the test area and the numbers of psyllids on each sprig were counted 24 h later. Sprigs with ≥7 psyllids were considered to be an aggregation. A total of seven ligands were tested individually. Four of the ligands (654, 717, 784, and 861) modulated psyllid settling and aggregation response, causing greater settling and aggregation to sprigs presented with the Cmac scent than to those sprigs with blank SPLAT. Presentation of one of the ligands (019) resulted in an opposite effect in which psyllid settling and aggregation levels were lower on sprigs with Cmac scent than on those with blank SPLAT. There were no differences in settling levels in the different treatment vials in the Ligand 905 experiment. In the Ligand 937 experiment, settling levels did not vary significantly between treatment vials although settling levels were relatively high in all treatment vials and there was a significant treatment effect. Increased settling and aggregation levels were largely not observed with in the vials with only the test ligands, and there was little effect of ligand concentration on psyllid response levels. This suggests that the test ligands themselves did not attract the psyllids but rather modulated the psyllid’s response to the Cmac scent. The results suggest that synthetic ligands of D. citri CBPs can be used to increase the effectiveness of citrus scent lures used to attract psyllids to monitoring traps and attract and kill devices

Mineral nutrition influences physiological responses of pear in vitro

Abnormal physiological responses of plant cultures such as shoot tip necrosis, callus, and hyperhydricity are some of the most difficult challenges in shoot micropropagation, and their causes are not well understood. Five Murashige and Skoog mineral salt factors, which influence the growth of pear shoot cultures, were tested in a five-dimensional surface response experimental design. Pyrus communis ‘Old Home × Farmingdale 87,’ ‘Horner 51,’ and ‘Winter Nelis’; Pyrus dimorphophylla; and Pyrus ussuriensis ‘Hang Pa Li’ shoot cultures were grown on 43 computer-designed treatments to represent the design space of all possible treatment combinations. Analysis of shoot response to these treatments identified the factors that both contributed to physiological disorders and remedied them. Undesirable callus formation was common for pear shoots cultured on standard medium and decreased on formulations with increased NH₄NO₃, Fe, and mesos (CaCl₂, KH₂PO₄, and MgSO₄) for most genotypes. Shoot tip necrosis varied with the genotype, but low mesos or low nitrogen concentrations contributed to the necrosis. Hyperhydricity was more prominent with low mesos or low NH₄NO₃. Hooked and upwardly curled new leaves were seen in most genotypes and resulted from use of low mesos in P. communis and low nitrogen for ‘Hang Pa Li’ and P. dimorphophylla. Fasciation and hypertrophy were seen infrequently and resulted from wide imbalances in several nutrients simultaneously. In general, standard concentrations of Murashige and Skoog iron and micros combined with high mesos and moderate nitrogen compounds produced normal shoots without physiological disorders.This is the publisher’s final pdf. The article is copyrighted by the Society for In Vitro Biology and published by Springer. It can be found at: http://link.springer.com/journal/11627Keywords: Mineral nutrition, Micropropagation, Pyrus, Nitrogen, Meso

Sonochemically-induced spectral shift as a probe of green fluorescent protein release from nano capsules

Encapsulation in the form of micro and nanocapsules is an attractive route for controlling the delivery and release of active proteins and peptides. Many approaches exist to probe the morphology of such capsules as well as their mechanisms of formation. By contrast, the release of proteins from such components in a complex biological environment has been challenging to probe directly. In this paper we show that the spectral differences between green fluorescent protein (GFP) in capsules and in its free form can be used to monitor in situ the release of the protein from the confinement of capsules. These findings represent a new route towards engineering the spectral characteristics of GFP through physical rather than chemical means. We demonstrate the use of GFP protein capsules for monitoring in real time the release of protein in live cells by exposing rat L6 myotubes to protein capsules. The GFP spheres with a blue fluorescent signal dissociate inside the L6 myotubes to individual GFP molecules with a change in fluorescent signal from blue to green. These sensitive spectral characteristics enabled us to resolve the dissociation of capsules inside the cells in both time and space. We discuss the implications of our results for quantifying parameters crucial for the delivery of proteins in biological environments

Mesos components (CaCl2, MgSO4, KH2PO4) are critical for improving pear micropropagation

Pear accessions and species show a broad response to tissue culture media due to the wide genetic diversity that exists in the available pear germplasm. An initial study of mineral nutrition using a systematic response surface approach with five Murashige and Skoog medium mineral stock solutions indicated that the mesos factor (CaCl₂, MgSO₄, and KH₂PO₄) affected most plant responses and genotypes, suggesting that additional studies were needed to further optimize these three mesos components for a wide range of genotypes. Short stature, leaf spots, edge necrosis, and red or yellow coloration were the main symptoms of poor nutrition in shoot cultures of 10 diverse pear genotypes from six species. A surface response experimental design was used to model the optimal factor and factor levels for responses that included overall quality, leaf character, shoot multiplication, and shoot height. The growth morphology, shoot length, and multiplication of these pear shoots could be manipulated by adjusting the mesos components. The highest quality for the majority of genotypes, including five P. communis cultivars, P. koehnei, P. dimorphophylla, and P. pyrifolia 'Sion Szu Mi', required higher concentrations (> 1.2x to 2.5x) of all the components than are present in Murashige and Skoog medium. 'Capital' (P. calleryana) required high CaCl₂ and MgSO₄ with low KH₂PO₄; for 'Hang Pa Li' (P. ussuriensis), low CaCl₂ and moderate to low MgSO₄ and KH₂PO₄ produced high-quality shoots. Suitable combinations of the meso nutrients produced both optimum shoot number and shoot length in addition to general good plant quality.Keywords: Phosphorous, Pyrus, Media optimization, Calcium, Magnesiu

Accumulation of Biomass and Mineral Elements with Calendar Time by Corn: Application of the Expanded Growth Model

The expanded growth model is developed to describe accumulation of plant biomass (Mg ha−1) and mineral elements (kg ha−1) in with calendar time (wk). Accumulation of plant biomass with calendar time occurs as a result of photosynthesis for green land-based plants. A corresponding accumulation of mineral elements such as nitrogen, phosphorus, and potassium occurs from the soil through plant roots. In this analysis, the expanded growth model is tested against high quality, published data on corn (Zea mays L.) growth. Data from a field study in South Carolina was used to evaluate the application of the model, where the planting time of April 2 in the field study maximized the capture of solar energy for biomass production. The growth model predicts a simple linear relationship between biomass yield and the growth quantifier, which is confirmed with the data. The growth quantifier incorporates the unit processes of distribution of solar energy which drives biomass accumulation by photosynthesis, partitioning of biomass between light-gathering and structural components of the plants, and an aging function. A hyperbolic relationship between plant nutrient uptake and biomass yield is assumed, and is confirmed for the mineral elements nitrogen (N), phosphorus (P), and potassium (K). It is concluded that the rate limiting process in the system is biomass accumulation by photosynthesis and that nutrient accumulation occurs in virtual equilibrium with biomass accumulation

Diversity and relationships of eggplants from three geographically distant secondary centers of diversity

Eggplant (Solanum melongena L.) was domesticated in the Indo-Birmanian region, which is also the primary center of diversity for this crop. From there eggplant spread to other regions, and diversity accumulated in several secondary centers of diversity. We have assessed the diversity and relationships of 52 accessions of eggplant from three geographically distant secondary centers of diversity (China, Spain, and Sri Lanka) using 28 morphological descriptors and 12 highly polymorphic genomic SSRs. A wide variation was found for most morphological traits, and significant differences among the three centers of diversity were detected for 22 of these traits. The PCA analysis showed that eggplants from the three origins were morphologically differentiated, and accessions from each of the three secondary centers of diversity presented a typical combination of morphological characteristics. In this respect, discriminant analysis showed that accessions could be correctly classified to their origin using only six traits. The SSR characterization identified 110 alleles and allowed obtaining a unique genetic fingerprint for each accession. Many alleles were found to be private to each origin, but no universal alleles were found for any of the origins. The PCA analysis showed that the genetic differentiation among origins was less clear than for morphological traits, although the analysis of the population structure shows that accessions mostly group according to the origin, but also provides evidence of migration among the three secondary centers of diversity. The genetic diversity (HT) within each origin was high, ranging between H-T = 0.5400 (Sri Lanka) and H-T = 0.4943 (China), while the standardized genetic differentiation (G'(ST)) among origins was moderate (G'(ST) = 0.2657). The correlation between morphological and SSR distances was non-significant (r = 0.044), indicating that both data are complementary for the conservation of germplasm and breeding of eggplant. These results are relevant for the management of genetic resources, breeding programmes, and evolutionary studies of eggplant.This work was financed by the Ministerio de Ciencia e innovacion (grants AGL2009-07257 and RF-2008-00008-00-00) (http://www.micinn.es). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Hurtado Ricart, M.; Vilanova Navarro, S.; Plazas Ávila, MDLO.; Gramazio, P.; Fonseka, HH.; Fonseka, R.; Prohens Tomás, J. (2012). Diversity and relationships of eggplants from three geographically distant secondary centers of diversity. PLoS ONE. 7:41748-41748. https://doi.org/10.1371/journal.pone.0041748S4174841748