Somatic hybrids of vegetable brassicas as source for new resistances to fungal and virus diseases

Somatic hybrids were produced by PEG-induced symmetric and asymmetric protoplast fusions in order to transfer resistance to Alternaria brassicicola, A. brassicae, Phoma lingam, Plasmodiophora brassicae and Turnip mosaic virus (TuMV) into Brassica oleracea var. capitata (cv. ‘Toskama’) and botrytis (cv. ‘Korso’). As resistance donors, ten species belonging to several genera of the family Brassicaceae including wild relatives were used. Of 2,189 plants (somatic hybrids, partially in vitro cloned) tested, 1,616 (73.8%) were resistant against at least one of the pathogens, indicating that, mostly, a successful resistance transfer has taken place. Five hundred and twenty-two hybrids showed multiple resistances to two, three and, in a single case, to four pathogens. Irrespective of the donor parents used in the fusion, a broad variability in symptom manifestation ranging from 0 (without symptoms) to 9 (highly susceptible) could be observed. With regard to the Alternaria pathogens, Sinapis alba, B. nigra and B. juncea were the most effective resistance donors, whereas fusions with Raphanus sativus resulted in the most hybrids with resistance to clubroot and TuMV. As could be shown especially in asymmetric fusions with S. alba, Barbarea vulgaris and Hesperis matronalis, transferred resistance to a pathogen may not correspond with resistance exhibited by the donor parent. Some combinations in which both parents were highly susceptible, e.g. R. sativus (+) B. oleracea var. capitata, yielded hybrids that exhibited strong resistance, e.g. to A. brassicicola, revealing that a new type of resistance might be occurring. With regard to the Alternaria pathogens, resistance expression was very unstable. Many hybrids into which (also variable) resistance of some donors, such as B. vulgaris, S. alba and B. carinata, was transferred became as highly susceptible as those of which the fusion parents did not show any resistance reaction (e.g. R. sativus). For reliable characterization of the resistance response, hybrids should be subjected to several resistance tests during growth period of the host, at least until flowering.     

A novel crop water analysis system: identification of water stress tolerant genotypes of canola (Brassica napus L.) using non‐invasive magnetic turgor pressure probes

Changing global climatic conditions and irrigation water shortages impose water stress conditions on crops. To develop genotypes tolerant to water stress necessitates reliable high‐throughput methods to study plant water status and water stress tolerance mechanisms. We report the use of a non‐destructive, automated, precise and rapid system for assessing real‐time water status in canola plants. Leaf patch clamp pressure probes were clamped on the leaves of four different genotypes of canola grown under field conditions. The data generated diurnal curves characterizing the pattern of turgor pressure maintenance within the leaves. A novel methodology termed ‘inverse hysteresis’ was developed to measure relative water stress levels in plants using the probe‐derived data. The inverse hysteresis data show that genotypes CT12 and CT15 had a higher ability to withstand water stress and were more tolerant to water stress than DS23 and DS35. The chlorophyll content and seed yield were also higher in CT12 and CT15. This novel analytical tool for monitoring water status in canola plants will be of great benefit in other crop species to efficiently screen genotypes for water stress tolerance.     

Structural stabilization of soil backfill with quicklime

The application of quicklime (CaO) to soil backfill for the amelioration of poorly aerated grave soils (sandy loam) was tested in a cemetery in Germany. Two grave simulations (soil pits 9 m × 2 m × 1.6 m, l × w × d) were set up. Variation sans was only excavated and refilled, while in variation qlm, 20 kg quicklime per m³ soil were added to the backfill. Soil matric potential and gas composition were recorded over a period of 24 months in the two refilled pits and in the surrounding undisturbed soil (ref) at the 50 cm and 135 cm depths, respectively. Soil samples were taken in the beginning from ref and in three‐month intervals from the treatments sans and qlm. Soil pH and CaCO₃ content, as well as bulk density (ρ_B), air capacity (AC), air conductivity (k_l), and saturated hydraulic conductivity (k_s) were measured. Excavation and backfill of the untreated soil (sans) led to an increase in ρ_B at the 50 and 90 cm depths and decreases in AC, k_l, and k_s when compared to ref. Quicklime application led to an increase in pH, the formation of CaCO₃ in the formerly carbonate‐free soil, consistently reduced ρ_B, and increased AC, k_l and k_s. Although the quicklime application did not lead to notably more negative matric potentials, it increased the O₂ concentration in the soil air and reduced the CO₂ concentration to zero. The results show that the application of quicklime helps the structural amelioration of cemetery soils even at relatively low clay contents.     

Adding dissolved organic carbon to simulate freeze‐thaw related N2O emissions from soil

It has been assumed that high winter N₂O emissions from soils are the result of increased amounts of microbially available organic C liberated during freezing and metabolized during subsequent thawing. In a laboratory experiment, we attempted to simulate freeze‐thaw events by adding dissolved organic C (DOC) to sieved soil of high water content (95% water‐filled pore space). In a full factorial design, CO₂ and N₂O emissions of a) soil samples provided with DOC extracted from frozen soil and b) soil samples frozen for 46 days and thawed were compared. Additionally, NO , DOC and microbial ATP contents of all treatments were repeatedly analyzed during the experiment. The addition of DOC to unfrozen soil (–F+C) resulted in a substantial (22‐fold) increase in N₂O emissions as compared to the control (–F–C). However, following thawing, the increase in N₂O emissions was much larger (828‐fold in +F–C and 1243‐fold in +F+C). Freezing, but not the addition of DOC led to increased CO₂ emissions. Neither treatment affected microbial adenylate content. By adding ¹⁵N‐labeled nitrate to the soil samples, the main process leading to elevated N₂O flux rates after both DOC addition and freeze‐thaw treatment was identified as denitrification. We conclude that the availability of C substrate plays an important role for freeze‐thaw‐related N₂O emissions. However, the fact that the simulated treatment and the freeze‐thaw treatment yielded significantly different amounts of N₂O suggests that both quantity and quality of available C differed between the treatments. The localization of the liberated substrate, i.e., the availability in situ, seems to be of major importance for the amount of N₂O produced.     

Large-scale copy number polymorphism in the human genome

The extent to which large duplications and deletions contribute to human genetic variation and diversity is unknown. Here, we show that large-scale copy number polymorphisms (CNPs) (about 100 kilobases and greater) contribute substantially to genomic variation between normal humans. Representational oligonucleotide microarray analysis of 20 individuals revealed a total of 221 copy number differences representing 76 unique CNPs. On average, individuals differed by 11 CNPs, and the average length of a CNP interval was 465 kilobases. We observed copy number variation of 70 different genes within CNP intervals, including genes involved in neurological function, regulation of cell growth, regulation of metabolism, and several genes known to be associated with disease.     

A Semiconductor-Based Photonic Memory Cell

Photonic signals were efficiently stored in a semiconductor-based memory cell. The incident photons were converted to electron-hole pairs that were locally stored in a quantum well that was laterally modulated by a field-effect tunable electrostatic superlattice. At large superlattice potential amplitudes, these pairs were stored for a time that was at least five orders of magnitude longer than their natural lifetime. At an arbitrarily chosen time, they were released in a short and intense flash of incoherent light, which was triggered by flattening the superlattice amplitude.     

Evaluation of different media and a BGM cell culture assay for isolation of Borrelia burgdorferi sensu lato from ticks and dogs

A co-culture assay for isolation of Borrelia burgdorferi sensu lato (sl.) from naturally infected ticks and dogs suspected of Lyme borreliosis (LB) was evaluated using buffalo-green-monkey (BGM) cells as the mammalian component. Four different media were tested for their ability to provide sufficient growth conditions for spirochetes and BGM cells. A total of 176 Ixodes ricinus ticks and 268 specimens from 98 dogs were used to compare cell-free culture with the BGM co-culture. A 1:1 mixture of Barbour-Stoenner-Kelly medium (BSK) and Eagle's minimum essential medium (EMEM) supported the growth of the two test strains, B. burgdorferi sensu stricto B31 and B. valaisiana VS116 to the same extent as BSK medium and the growth as well as the viability of BGM cells in this medium were the same as in EMEM. Using the 1:1 mixture of BSK and EMEM, borrelial growth measured in co-culture with BGM cells did not differ significantly from corresponding values obtained in cell-free cultures. In cell-free culture the isolation rate of B. burgdorferi sl. from ticks was significantly higher in BSK/EMEM 1:1 than in BSK medium (P < 0.01). Co-culture with BGM cells had no significant influence on the isolation rate of borreliae from ticks. However, a significant amount of isolates were obtained by one of the procedures only. Analysing canine specimens accordingly, spirochetes were grown from the blood of one dog after four weeks in BGM cell co-culture. The isolate was classified as B. afzelii by PCR-coupled restriction fragment length polymorphism analysis.     

Product quality and genome analysis in pig production--a review

Product quality in the pig is defined by the choice of lean meat including a reasonable intramuscular fat content and good water binding capacity, which can be produced and marketed at a reasonable price, based on good fattening performance and disease resistance. Traits of product quality are mostly of polygenic character, while some of these genes show larger effects. Genome analysis intends to identify the genetic basis of phenotypic trait variation and to complement conventional phenotypic selection criteria by direct regarding of the nucleotide level, thus marker assisted selection. The present paper describes the most important markers in use to improve product quality in swine, and shows perspectives of genome analysis in this regard, including positional and functional strategies.