Discrimination of ‘San Marzano’ accessions: A comparison of minisatellite, CAPS and SSR markers in relation to morphological traits

‘San Marzano’ (SM) is one of the most widely known tomato (Solanum lycopersicum L.) cultivars, and is a classic example of a local variety with a premium value. Unfortunately, the original cultivated form is underrepresented in the Protected Denomination of Origin (PDO) area because of the incidence of contaminant and phenotypically similar genotypes. Our aim was to examine the ability of three DNA marker systems (minisatellite, cleaved amplified polymorphic sequence (CAPS) and simple sequence repeat (SSR)) to reveal the genetic diversity of tomato accessions that were, based on a morphological analysis, very similar. The data indicate that both minisatellites and SSRs can be used to genetically distinguish the analysed materials. Furthermore, these two marker systems depict relationships consistent with the hierarchal pattern obtained by the morphological data. As locally cultivated tomato accessions are often characterised by some degree of genetic variability, our results will be valuable in facilitating the purification, management and breeding of tomato germplasms. The differences between the marker systems employed are also discussed in relation to their usefulness in the agro-food chain.     

Genetic diversity and population structure of Brachiaria brizantha (A.Rich.) Stapf accessions from Ethiopia

Brachiaria is a tropical, warm-season grass native to Africa. It is an extensively cultivated forage in the tropics with proven benefits on livestock productivity. Brachiaria is well-known for high biomass production, animal nutrition, carbon sequestration, biological nitrification inhibition, soil conservation, and adaptation to drought and low fertility soils. However, the use of Brachiaria grass for fodder production in Africa has been little explored largely due to lack of cultivars suitable to different production environments. The exploration and use of natural diversity is fundamental for an efficient Brachiaria breeding program. We analysed genetic diversity and population structure of 112 Ethiopian Brachiaria brizantha accessions using 23 microsatellite markers. A total of 459 alleles were detected with an average polymorphic information content of 0.75 suggesting high discriminating ability of these markers. The molecular variance analysis showed a high contribution (86%) of within-cluster differences to the total variation. Three allelic pools revealed by STRUCTURE analysis in 112 accessions were in agreement with the clustering patterns seen in neighbor-joining tree and principal coordinates analyses. A core collection of 39 B. brizantha accessions was constituted. This study concludes a high genetic diversity of Ethiopian B. brizantha accessions and their importance in Brachiaria breeding programs.     

Resistance mechanisms of wild tomato germplasm to infection of Oidium neolycopersici

Tomato powdery mildew (Oidium neolycopersici) is one of the most devastating diseases of cultivated tomatoes worldwide. Although the first epidemics were recorded more than 25 years ago many aspects of this host-pathogen interaction are still not well understood. Detailed morphological and molecular studies of the anamorphs confirmed that O. neolycopersici is phylogeneticaly close to Erysiphe aquilegiae var. ranunculi. Host range is rather broad, apart from Solanaceae hosts were found in the families Apocynaceae, Campanulaceae, Crassulaceae, Cistaceae, Cucurbitaceae, Linaceae, Malvaceae, Papaveraceae, Pedialiaceae, Scrophulariaceae, Valerianaceae a Violaceae. Non-host resistance within these families is not based on inhibition of formation of primary haustorium, however, on post-haustorial hypersensitive reponse and another type of non-hypersensitive resistance. Screening of wild Solanum species (previous Lycopersicon spp.) germplasm revealed valuable sources of resistance (S. habrochaites, S. pennellii, S. cheesmaniae, S. chilense, S. peruvianum). The main resistance mechanism was found to be a hypersensitive response (HR), in some cases followed by limited development of the pathogen. However, there is a broad variation in resistance response on the histological and cytological level. Interaction between many wild Solanum spp. and O. neolycopersici is race-specific, at least three races were differentiated. In some interspecific crosses (S. lycopersicum × S. habrochaites) adult plant resistance was observed. Biochemical studies focusing on production of reactive oxygen species (ROS) and peroxidase activity during infection of O. neolycopersici showed that production of ROS and activity of corresponding enzymes is related to activation of defence responses in genotypes of wild Solanum sect. Lycopersicon. The significance of nitric oxide (NO) in O. neolycopersici pathogenesis was supported by experiments with NO donors and scavengers. In moderately resistant genotype S. chmielewskii, treatment by heat stress caused slight deceleration of pathogen development, increased production of jasmonic acid (JA) and abscisic acid (ABA) and increased peroxidase activity in infected plants. The different degree of tomato resistance/susceptibility did not markedly change the rate and extent of photosynthetic response to O. neolycopersici; only minimal impairment of photosynthesis was found in both susceptible and moderately resistant genotypes during the first 9 days after inoculation. The accumulated evidence confirm a crucial role of localised increased production of ROS and reactive nitrogen species (RNS) in response to pathogen penetration into plant tissue and its involvement in the plant resistance responses including the initiation and progression of plant cell death in host wild Solanum species. Crucial points of further research are discussed.     

Kinetics and electron transport of soil hydrogenases catalyzing the oxidation of atmospheric hydrogen

The soil hydrogenases of chernozem and eolian sand were different with respect to their kinetic properties. Increase of soil moisture above optimum moisture content or prior incubation of the soils under very high H₂-mixing ratios (i.e. 1%) resulted in a decrease of V_max or in an increase of the K_m of the H₂ oxidation reaction. Under anaerobic conditions, the K_m for H₂ was higher and V_max was lower than under aerobic conditions. The anaerobic H₂-oxidation activity of both soils was stimulated by the addition of artificial electron acceptors with redox potentials of at least 80 mV. Ferricyanide as the most efficient stimulator did not function as a final electron acceptor for anaerobic H₂-oxidation, but acted as a catalyst by bypassing a rate-limiting electron transport step. In eolian sand, the aerobic as well as the anaerobic activity for atmospheric H₂ oxidation decreased upon exposure to very high H₂-mixing ratios (i.e. 1%). A similar effect was observed after incubation with ferricyanide which enabled the inflow of excess electrons from soil reductants or added NADH into the electron transport system of the soil hydrogenase with anaerobic activity. The activity for atmospheric H₂ oxidation was regenerated during incubation in H₂-free atmospheres, especially in the presence of oxygen. Inhibition and regeneration were probably due to alterations in components of the soil hydrogenases caused by the extent of a maximal electron flow through the electron transport system of the soil hydrogenases. Two classes of hydrogenase activities were discerned in eolian sand: one predominantly active under aerobic and the other under anaerobic conditions.     

The phosphorus status of German cropland—An inventory of top‐ and subsoils

Background : In search for more sustainable crop production, the subsoil has recently come into focus as considerable reservoir of nutrients and water. Aims : Dimensions of subsoil phosphorus (P) reserves are yet largely unknown but crucial for identifying regions suitable to include subsoil into sustainable management strategies. Methods : We analyzed stocks of total and plant‐available (calcium acetate lactate‐extractable) P in 96 representative soil profiles of German arable land down to 1 m depth. Results : We found that the German arable soils stored, on average, 8 t ha^?1 of total P, of which nearly 500 kg ha^?1 were readily plant‐available. Notably, one third of plant‐available P was located below the plow layer and one fifth even at depths below 0.5 m. The depth gradients of plant‐available P stocks were affected more by major reference soil group than by texture. Generally, Chernozem but also Anthrosol, Gleysol and Fluvisol exhibited the largest P stocks in German cropland. The contribution of plant‐available P to total P stocks was larger in sandy and extremely acidic (pH < 4.5) soils compared with more fine‐grained and slightly acidic to alkaline soils, possibly because fertilization compensated for overall lower total P stocks at these sites. Generally, the more P was stored in topsoils, the more P was stored also in subsoils. Conclusions : A hypothetical crop utilization of 10% from plant‐available P stocks and 0.1% from total P stocks from shallow subsoil could compensate for P fertilization by ca. 8 kg ha^?1, but the rate of plant‐available P replenishment in subsoil likely remains the crucial factor for the role of subsoil P stocks in crop nutrition. Generally, the large P reserves found in subsoil could act as an ‘insurance' system for crops.     

Bacterial ghost technology for pesticide delivery

Bacterial ghosts are nondenaturated empty cell envelopes of Gram-negative bacteria produced by E-mediated lysis. Such envelopes from the plant-adhering bacterium Pectobacterium cypripedii were tested for their ability to adhere to plant material and to be used as carriers for pesticide delivery. We show, using fluorescence-labeled P. cypripedii ghosts, that depending on the target plants 55 or 10% (rice or soya, respectively) of the applied bacterial ghosts was retained on the leaves after heavy simulated rain (84 mm). Furthermore, the bacterial ghosts could be loaded with the lipophilic triazole fungicide tebuconazole. In subsequent plant experiments in the glass house, the efficacy of the loaded bacterial ghost for resistance to rainfall and the protective and curative effects against the pathogens Erysiphe graminis, Leptosphaeria nodorum, and Pyrenophora teres on barley and wheat and against Sphaerotheca fuliginea on cucumber were tested. The bacterial ghosts were compared primarily with a commercial tebuconazole formulation, a wettable powder, as it has similar physical characteristics. The comparison revealed similar effects and showed consistently higher or comparable efficacy against the pathogens. The standard operational comparison with the most protective, cereal specific emulsion of oil in water displayed that the bacterial ghosts had equal to or lower efficacy than the emulsion. This study confirmed the potential of bacterial ghost platform technology as a new alternative carrier system for pesticides.     

High alcohol consumption in Germany: results of the German National Health Interview and Examination Survey 1998

OBJECTIVE: To analyse the alcohol consumption behaviour of the German adult population, with a focus on the characteristics of persons drinking more than the tolerable upper alcohol intake level (TUAL) of 10-12 g day(-1) for healthy adult women and 20-24 g day(-1) for healthy adult men. DESIGN AND SETTING: For the German National Health Interview and Examination Survey 1998, a representative sample of free-living adults was drawn. A total of 7124 participants were interviewed comprehensively about their sociodemographic background, lifestyle and eating habits including alcohol consumption. SUBJECTS: A sub-sample of 4030 women and men, 18-79 years old, who were involved in the integrated German Nutrition Survey. RESULTS: About 16% of women and 31% of men had mean alcohol consumption above the TUAL. Among other factors, the inclination to exceed the TUAL was related to middle-age, high socio-economic status, smoking and use of soft drugs. Among both women and men, a high proportion of persons drinking above the TUAL was observed among those consuming low amounts of soft drinks, fruit, poultry, milk products, bread and cake/biscuits. Women preferred to drink wine, whereas men preferred to drink beer. CONCLUSIONS: Many Germans have an alcohol consumption level above the TUAL and thus are supposed to be at increased risk for alcohol-associated diseases.     

Application of central-place foraging theory shows the importance of Mediterranean dehesas for the conservation of the cinereous vulture, Aegypius monachus

The dehesa (oak woodland) is an extensive agro-pastoral ecosystem characteristic of the Western Mediterranean countries which is suffering a great transformation process since 1950. Although its distribution largely overlaps with several endangered species, there is scarce information on how they use this human-transformed habitat. We studied the foraging habitat selection of one of them, the cinereous vulture Aegypius monachus. We radio-tracked 14 cinereous vultures in one of the largest European colonies from 1998 to 2000. Used and available habitats were compared at two scales using compositional analysis. Moreover, we developed a distance-based GLMM for assessing habitat selection in this central-place forager species, by taking into account the spatial distribution of habitat patches in relation to the location of the colony. Home ranges overlapped over a total surface of 592,527 ha around the colony, and both individual home ranges and travel foraging distances (mean 27.86 km, maximum 86 km) were larger during the breeding season. All cinereous vultures avoided agricultural lands within their home ranges throughout the year. Habitat use in relation to the distance to the colony pointed out that dehesas were positively selected in spite of being on average far away from the colony than other habitats, a result that was consistent among individuals and seasons. The cinereous vulture thus depends for its conservation not only on the protection of breeding areas, as has been so far considered, but also on the maintenance of well-conserved dehesas close to the colonies. Preserving the cinereous vultures could contribute to the economic sustainability of dehesas by attracting PAC funds for their traditional low-intensity exploitation. Although other species may also benefit from this study since cinereous vulture could be a “flagship” for the large-scale conservation of Mediterranean oak woodlands and associated biodiversity, more fine local management guidelines should be performed on the basis of studies on more sensitive species.     

Schätzung des Humusgehaltes nach der Munsell-Farbhelligkeit

Calculation of the humus content of soil samples by the Munsell-value The log values of humus contents (0.1–15%) and the Munsell-values of 156 dry or moist soil samples from Northern Germany were strongly correlated, especially in additional consideration of Munsell-chromas and soil texture.