Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes   总被引：2，自引：1，他引：1  

Maria Scurrah  Carolina Celis-Gamboa  Susana Chumbiauca  Alberto Salas  Richard G. F. Visser 《Euphytica》2008,164(3):881-892

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Map- vs. homology-based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew     

Stefano Pavan  Zheng Zheng  Mariya Borisova  Petra van den Berg  Concetta Lotti  Claudio De Giovanni  Pim Lindhout  Hans de Jong  Luigi Ricciardi  Richard G. F. Visser  Yuling Bai 《Euphytica》2008,162(1):91-98

The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregating F₂ population to merge these markers with all the ol-2 linked amplified fragment length polymorphism (AFLP^®) markers previously identified in an integrated genetic map. By screening a tomato bacterial artificial chromosome (BAC) library, we detected two BAC clones containing two expressed sequence tags (ESTs) homologous to the gene mlo, responsible for powdery mildew resistance in barley, as well as an ol-2-linked marker. Chromosomal mapping by Fluorescence in situ Hybridization (FISH) revealed major signals of the two BAC DNAs in the pericentromeric heterochromatin of the short arm of chromosome 4, in the same region where the ol-2 gene was previously mapped. The genetic and cytogenetic co-localisation between ol-2 and tomato mlo-homologue(s), in addition to the similarity of ol-2 and mlo resistances for both genetic and phytopathological characteristics, suggests that ol-2 is likely a mlo-homologue. Thus, a homology-based cloning approach could be more suitable than positional cloning for ol-2 isolation.  相似文献   

Societal Costs of Late Blight in Potato and Prospects of Durable Resistance Through Cisgenic Modification   总被引：6，自引：4，他引：2  

A. J. Haverkort  P. M. Boonekamp  R. Hutten  E. Jacobsen  L. A. P. Lotz  G. J. T. Kessel  R. G. F. Visser  E. A. G. van der Vossen 《Potato Research》2008,51(1):47-57

In the European Union almost 6 Mha of potatoes are grown representing a value of close to €6,000,000,000. Late blight caused by Phytophthora infestans causes annual losses (costs of control and damage) estimated at more than €1,000,000,000. Chemical control is under pressure as late blight becomes increasingly aggressive and there is societal resistance against the use of environmentally unfriendly chemicals. Breeding programmes have not been able to markedly increase the level of resistance of current potato varieties. New scientific approaches may yield genetically modified marker-free potato varieties (either trans- and/or cisgenic, the latter signifying the use of indigenous resistance genes) as improved variants of currently used varieties showing far greater levels of resistance. There are strong scientific investments needed to develop such improved varieties but these varieties will have great economic and environmental impact. Here we present an approach, based on (cisgenic) resistance genes that will enhance the impact. It consists of five themes: the detection of R-genes in the wild potato gene pool and their function related to the various aspects in the infection route and reproduction of the late blight causing pathogen; cloning of natural R-genes and transforming cassettes of single or multiple (cisgenic) R-genes into existing varieties with proven adaptation to improve their value for consumers; selection of true to the wild type and resistant genotypes with similar qualities as the original variety; spatial and temporal resistance management research of late blight of the cisgenic genetically modified (GM) varieties that contain different cassettes of R-genes to avoid breaking of resistance and reduce build-up of epidemics; communication and interaction with all relevant stakeholders in society and transparency in what research is doing. One of the main challenges is to explain the different nature and possible biological improvement and legislative repercussions of cisgenic GM-crops in comparison with transgenic GM-crops. It is important to realize that the present EU Directive 2001/18/EC on GM crops does not make a difference between trans- and cisgenes. These rules were developed when only transgenic GM plants were around. We present a case arguing for an updating and refinement of these rules in order to place cisgenic GM-crops in another class of GM-plants as has been done in the past with (induced) mutation breeding and the use of protoplast fusion between crossable species.  相似文献   

An analysis of the persistence and potency of film‐coated seed protectant as influenced by various storage parameters     

Sherry Rachel Jacob  MB Arunkumar  Madhuban Gopal  Chitra Srivastava  SN Sinha 《Pest management science》2009,65(7):817-822

BACKGROUND: An efficient delivery system for seed‐protectant chemicals is needed in light of several disadvantages of conventional seed treatment methods. This study evaluates the efficacy of film‐coat application in maintaining the persistence and potency of imidacloprid on Lycopersicon esculentum (L.) Mill. seeds after simultaneous storage under ambient and regulated environment in paper and aluminium packages. RESULTS: High‐performance liquid chromatography (HPLC) revealed 0.135 mg kg^?1 of herbage material to be the threshold value beyond which absolute control was obtained, and with film coating the latter was achieved even with half‐dosage seed treatment, irrespective of the storage condition. The technique provided early protection to the crop and also nullified the deleterious effects of ambient storage on the persistence and potency of the pesticide. CONCLUSION: Film coating enabled superior pesticide dosage as well as higher biological efficacy to be achieved. Hence, in addition to being an ecofriendly alternative, the technique would be a more economically viable option for storage of treated seeds. Copyright © 2009 Society of Chemical Industry  相似文献   

Nutrient dynamics—wind and water erosion at the village scale in the Sahel     

S. M. Visser  G. Sterk 《Land Degradation \u0026amp; Development》2007,18(5):578-588

The loss of nutrients by wind erosion is generally attributed to losses by suspension, since suspension selectively removes the finest particles. However, because the main mass of sediment is moved by saltation during an event, the main mass of nutrients is also moved by saltation. Nutrient losses from one field during one wind erosion event can be as high as 73 per cent of the N and 100 per cent of the P needs for crop production. Vegetated areas have a higher dust deposition because of the filtering effect of the vegetation and the reduction of drag forces causing a higher deposition. This refutes the general assumption that deposition of suspended dust is homogeneous for a larger area. In the Sahel, two types of dust can be distinguished, the Harmattan dust is richer in nutrients and regarded as a real input of nutrients. The convectional storm dust has a nutrient content comparable with the nutrient content of the dust fraction of the topsoil and can't be regarded as input of nutrients. From research on nutrient losses by water erosion at the plot scale, it is concluded that nutrient erosion by water can cause serious losses of nutrients. But at the village scale, the losses are considerably smaller than at the plot scale. Measurement and subsequent nutrient budget analyses around the village Dangadé in Burkina Faso indicated that this area is especially vulnerable for wind erosion by saltation transport. This demonstrates that in the Sahelian environment, the effect of wind erosion at the village scale can't be ignored. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Effect of an Intervertebral Disk Spacer on Stiffness After Monocortical Screw/Polymethylmethacrylate Fixation in Simulated and Cadaveric Canine Cervical Vertebral Columns     

Bianca F. Hettlich Dr Med Vet  Diplomate ACVS  Matthew J. Allen Vet MB  PhD  Gabriela S. Glucksman BS  Geoffrey T. Fosgate DVM  PhD  Diplomate ACVPM  Alan S. Litsky MD  ScD 《Veterinary surgery : VS》2014,43(8):988-994

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IMAGING OF A SPINAL NEPHROBLASTOMA IN A DOG     

J. Fraser Mc  Connell  BVM&S  Laurent S.  Garosi  DVM  Ruth  Dennis  Vet MB  Ken C.  Smith  BVM&S  PHD 《Veterinary radiology & ultrasound》2003,44(5):537-541

An 8-month-old German Shepherd dog was presented for investigation of pelvic limb gait abnormality. Neurolocalization indicated a T3-L3 spinal cord lesion. The myelographic appearance was of an intramedullary lesion at T9/10, but upon subsequent magnetic resonance imaging it was determined that the mass was extramedullary. A diagnosis of nephroblastoma was made on histological examination. The imaging features of this rare tumor and the differentiation of intradural-extramedullary and intramedullary masses are discussed.  相似文献   

The passive protection of lambs against Clostridium perfringens type D with semi-purified hyperimmune serum     

M W Odendaal  J J Visser  W J Botha  H Prinsloo 《The Onderstepoort journal of veterinary research》1988,55(1):47-50

Weaned lambs, having a detectable level of maternal antibodies (1-2 units/ml) against C. perfringens type D, showed protective antitoxin levels lasting for 29 days after receiving a single parenteral dose of 200 units/kg hyperimmune serum. Lambs, having no maternal antibodies (less than 0,07 units/ml) to C. perfringens type D but receiving the same dose of hyperimmune serum, maintained protective antibody levels for only 21 days. Three weeks after the titres fell below the minimum protective level of 0,15 units/ml, both these groups were treated again in the same manner. The passive immunity conferred in both groups now lasted for 42 days. When the hyperimmune serum was administered to lambs already immunized by vaccination, a slight increase was noted in the antibody titre.  相似文献   

The use of bleach and hydrogen peroxide in endodontics irrigation     

C J Visser 《Journal of veterinary dentistry》1988,5(2):3-4

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Some observations on the narcotizing ability of electric currents on the common carp Cyprinus carpio     

W T Barham  H J Schoonbee  J G Visser 《The Onderstepoort journal of veterinary research》1989,56(3):215-218

Some effects of alternating current electronarcosis and of rectified current electronarcosis on C. carpio were investigated. In all instances recovery from narcosis was accompanied by convulsive spasms. Haemorrhaging of the gills was also observed to occur. Carp do not appear to be suitable candidates for electronarcosis.  相似文献