Genetic diversity and population structure of worldwide eggplant (<Emphasis Type="Italic">Solanum melongena</Emphasis> L.) germplasm using SSR markers

Two hundred and eighty-seven worldwide eggplant accessions were examined for genetic diversity and population structure analysis with 45 SSR markers. The results resolved 242 alleles across all the accessions. Gene diversity ranged from 0.104 to 0.832 with an average of 0.558. Polymorphic information content ranged from 0.102 to 0.815 with an average of 0.507. The genetic diversity analysis classified all accessions into four groups, and the data showed that gene exchanges occurred in two groups during germplasm introduction, domestication, and improvement; however, the frequency was low. Population structure analysis classified 269 accessions into two subgroups, and the remaining 18 accessions were defined as admixed. The accessions from the same geographic origin tend to be clustered into same group. These results provide new insights into the exploitation of genetic diversity of germplasm for eggplant breeding program.     

Molecular cytogenetic identification of newly synthetic <Emphasis Type="Italic">Triticum kiharae</Emphasis> with high resistance to stripe rust

Six new amphiploids, Triticum kiharae Dorof. et Migusch. (2n?=?6x?=?42, A^tA^tGGDD), are described in this study. They were developed by the chromosome doubling of F₁ hybrid crosses between Triticum timopheevii Zhuk. (A^tA^tGG) with high resistance to stripe rust and Aegilops tauschii Cosson (DD) by colchicine treatment. These amphiploids showed a high level of fertility of 68–80% and exhibited relatively normal chromosome pairing in meiotic metaphase I. Individual chromosomes of T. kiharae could be identified by multicolor fluorescence in situ hybridization using the combination of oligonucleotides probes Oligo-pSc119.2-1, Oligo-pTa535-1, and Oligo-pTa71-2. T. kiharae exhibited high resistance to predominant stripe rust races CYR34, CYR31, CYR32, CYR33, and SY11-4 both during the seedling and adult stages. However, high molecular weight glutenin subunits from Ae. tauschii parents were only partially expressed in the T. kiharae background. These T. kiharae lines provide novel materials to widen the genetic diversity of the common wheat gene pool.     

Electrophoretic variation in seed proteins and interrelationships of species in the genus <Emphasis Type="Italic">Oryza</Emphasis>

Comparative studies of two cultivated and sixteen wild species of the genus Oryza were carried out using one- and two-dimensional gel electrophoresis for variation in their seed proteins for interrelationships of these species. A number of polypeptides in the range of molecular weight 13–110 kDa were seen to vary. Under reducing conditions, polypeptides spread over the regions of mol. wt. 33–40.5, 25–27 and 19–21.5 kDa exhibited maximum variation in their patterns. Two-dimensional gel electrophoresis revealed the occurrence of disulphide-linked glutelin polypeptide pairs of mol. wt. 60, 58, 52 and 25 kDa breaking into a large and a small subunit each in the range of mol. wt. 18–40.5 and 16–25 kDa respectively in Oryza sativa. The number of such polypeptide pairs varied from 2 to 6 in different species and also in O. sativa showed variation in mol. wts. of their constituent subunits. The UPGMA dendrogram revealed that most of the Oryza species occurred in different clusters and subclusters and thus did not share very close relationships. The undisputed and closest relationship observed was that of cultivated rice O. sativa with the O. rufipogon followed by that with O. nivara. The African cultivated O. glaberrima occurring on the nearest branch of the same subcluster, thereby, supporting the phylogenetic of these species suggested in earlier studies. Eight diploid species and seven tetraploid species were included in one part of the dendrogram while the remaining two species with AA genome i.e. O. glumaepatula and O. meridionalis and one with FF i.e. O. brachyantha stood separately from these as scattered in the group of seven tetraploid species with BBCC, CCDD and HHJJ genomes. The tetraploids O. alta, O. latifolia and O. grandiglumis with CCDD genomes which occurred on the farthest part were distantly related with O. sativa. The cyanogen bromide peptide maps and two dimensional gel electrophoresis also supported the closest relationship between O. sativa and O. rufipogon.     

Effect of <Emphasis Type="Italic">Silene vulgaris</Emphasis> and Heavy Metal Pollution on Soil Microbial Diversity in Long-Term Contaminated Soil

In this study, we analysed the impact of heavy metals and plant rhizodeposition on the structure of indigenous microbial communities in rhizosphere and bulk soil that had been exposed to heavy metals for more than 150 years. Samples of the rhizosphere of Silene vulgaris and non-rhizosphere soils 250 and 450 m from the source of emission that had different metal concentrations were collected for analyses. The results showed that soils were collected 250 m from the smelter had a higher number of Cd-resistant CFU compared with the samples that were collected from 450 m, but no significant differences were observed in the number of total and oligotrophic CFU or the equivalent cell numbers between rhizosphere and non-rhizosphere soils that were taken 250 and 450 m from the emitter. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis of the denaturing gradient gel electrophoresis (DGGE) profiles, as well as a cluster analysis that was generated on the phospholipid fatty acid (PLFA) profiles, showed that the bacterial community structure of rhizosphere soils depended more on the plant than on the distance and metal concentrations. The sequencing of the 16S rDNA fragments that were excised from the DGGE gel revealed representatives of the phyla Bacteroidetes, Acidobacteria, Gemmatimonadetes, Actinobacteria and Betaproteobacteria in the analysed soil with a predominance of the first three groups. The obtained results demonstrated that the presence of S. vulgaris did not affect the number of CFUs, except for those of Cd-resistant bacteria. However, the presence of S. vulgaris altered the soil bacterial community structure, regardless of the sampling site, which supported the thesis that plants have a higher impact on soil microbial community than metal contamination.     

Hydroxyl Radical Generation and Contaminant Removal from Water by the Collapse of Microbubbles Under Different Hydrochemical Conditions

The present study addresses the mechanism of hydroxyl radical (·OH) generation by the collapse of microbubbles in water solution. The influence of gas supply and flow rate, solution pH, and ionic strength on the aeration efficiency, free radical generation, and contaminant removal (take methylene blue as an example) are elucidated. The results showed that the degradation rate of methylene blue by ·OH increased with flow rate as well as in acidic or alkaline solutions compared to that in neutral conditions. ·OH was shown to be produced by the reaction between protons and oxygen radicals generated by the decomposition of O₂ rather than water molecules. A greater concentration of O₂ or H⁺ thus promoted the reaction, resulting in effective removal at a high flow rate or low pH. Nevertheless, there was considerable methylene blue removal at high pH, driven by the production of the dye cation through the dissociation of methylene blue and the high electronegativity of bubbles at high pH, thus enhancing interface adsorption and degradation, as well as by the high ionic strength of the solution helping to generate ultrafine bubbles and maintaining them through ionic shielding. The current work provides useful insights into the application of microbubble as a promising technique.     

Organics Wastewater Degradation by a Mesoporous Chromium-Functionalized γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> with H<Subscript>2</Subscript>O<Subscript>2</Subscript> Assistance

In this study, a mesoporous chromium-functionalized γ-Al₂O₃ (Cr/γ-Al₂O₃) catalyst was prepared by an impregnation method, and the catalytic activity was evaluated by the degradation of organics wastewater. The prepared catalyst was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, nitrogen adsorption-desorption experiments, and scanning electron microscopy. The characterization results confirmed that the pores in the Cr/γ-Al₂O₃ catalyst distributed broadly in the mesoporous region, and the active chromium species were highly dispersed on the catalyst surface. The catalytic activity tests showed that the Cr/γ-Al₂O₃ catalyst exhibited a superior performance for the degradation of organics wastewater with H₂O₂ assistance. And the methylene blue (MB) disappeared within 20 min and the COD removal reached 76.5% within 40 min for the MB-simulated wastewater; for the phenol-simulated wastewater, the phenol removal was above 95% and the corresponding COD removal reached 71% within 40 min. Such an excellent catalytic performance demonstrates that the Cr/γ-Al₂O₃ catalyst has a potential application in the degradation of complex organics wastewater simultaneously.     

Solar Photocatalysis Using Fixed-Film TiO<Subscript>2</Subscript> for Microcystins from Colonial <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis>

Microcystins (MCs) are endotoxins produced by cyanobacteria in freshwaters globally. With known potential for human health risks, rapid and effective treatment methods are needed for MCs. Previous studies have shown photocatalysis can achieve rapid half-lives with UV lamps and slurries of TiO₂. In this experiment, rates and extents of solar photocatalysis of MCs were measured using bench-scale reactors with fixed films of TiO₂ for solutions with a range of cellular:aqueous MC ratios. Since cellular MCs can be removed physically, photocatalysis rates were measured following sand filtration to discern the extent of MC removal post-filtration. Since UV energy drives photocatalysis using TiO₂, rates of removal were calculated as a function of cumulative UV insolation and time. For water containing < 10% aqueous MC, filtration removed 90% of total MC, and the subsequent photocatalysis half-life was 0.37 MJ/m² (or 111 min). For water with ~?50% aqueous MCs, filtration removed 52% of the total MCs, and the average half-life for photocatalysis was 0.38 MJ/m² (or 138 min). For the >?90% aqueous MC treatment, filtration removed 0% MCs, and the photocatalysis half-life for MCs was 0.37 MJ/m² (or 135 min). Previous studies have used clarified waters; however, results from this study are likely representative of scenarios with waters containing confounding water characteristics and use of solar light for UV, as anticipated in developing countries with less advanced water treatment methods. Photocatalysis is a rapid and effective process for decreasing concentrations of MCs and could be useful for mitigating risks from MC exposures in drinking water.     

Isolation and Characterization of the Tellurite-Reducing Photosynthetic Bacterium, <Emphasis Type="Italic">Rhodopseudomonas palustris</Emphasis> Strain TX618

A novel tellurite-resistant photosynthetic bacterium, Rhodopseudomonas palustris strain TX618, was isolated from wastewater and reduction of tellurite by this strain was investigated. The results showed that Rhodopseudomonas palustris strain TX618 could reduce tellurite to elemental tellurium, both anaerobically and aerobically. During anaerobic and illuminated growth, strain TX618 possessed a high-level resistance and removal efficiency to tellurite, that it could resist up to 180 mg/L Na₂TeO₃ in the medium and removed 91.9% of 90 mg/L Na₂TeO₃ over 8 days. The high efficiency in the removal of tellurite could sustain wide variations in pH (5.0–9.0), temperature (20–40 °C), light intensity (1500–3000 lx), and initial tellurium concentration (30–180 mg/L Na₂TeO₃). It could be observed by scanning electron micrograph (SEM), transmission electron micrograph (TEM), and X-ray diffraction (XRD) analysis that the cells suffered serious deformation due to the toxicity of tellurite, and the less toxic black precipaite (Te⁰) generated by bioreduction of tellurite mostly located in the central cytoplasm. This is the first study to observe that Rhodopseudomonas palustris can reduce tellurite to elemental tellurium, which will provide a new microbial species for bioremediation and biotransformation of toxic tellurite.     

Prevalence of Concentrated Flow Paths in Agricultural Fields in Southern Illinois

Literature on prevalence of concentrated flow paths (CPFs) in agricultural fields are limited at field scale with only few studies that address occurrence of CFPs at large geographic extent. This study used high-resolution Light Detection and Ranging (LiDAR) data to identify CFPs in agricultural fields and calculate the percentage of the fields drained by CFPs at a county scale. In 389 agricultural fields across Jackson County, southern Illinois, this study also investigated the association between field characteristics and CFP formation using multiple regression and CART analysis. The mean number of CFPs in a field was 5 with a minimum of 0 and maximum of 17 CFPs. The majority of the CFPs fell under the large category for CFP length and drainage area that corresponds with high mean percent (81%) of field area drained by the CFPs. Further, 85% of the fields had more than 70% of their area drained by CFPs. The multiple regression and CART analysis showed slope as an important factor influencing CFP characteristics such as number of CFPs and CFP length. Both analyses also indicated physical soil properties such as bulk density, soil erodibility factor, saturated hydraulic conductivity, LS factor, organic matter, and percent sand were also predictors of the CFP characteristics. However, these factors explained only 2 to 12% of the variation observed. The significant presence of CFP’s has important implications for water quality since current conservation practices such as riparian buffers were not designed to address concentrated flow from agricultural fields.