Risk under construction: The German discourse on the ban of MON810

Food crises ranging from BSE to EHEC have time and again demonstrated that uncertainrisks in the area of food safety constitute one of the main societal challenges we arecurrently facing. Their nature as “possible, new, imaginable hazards, with which societyhas no or limited experience” (van Asselt and Vos, 2008) leads to situations in whichtraditional means of science prove to be inadequate for drawing suitable conclusionsinforming how the uncertain risk is to be handled. This challenge is particularly visible inthe regulation of genetically modified organisms (GMOs): they have been characterizedas an uncertain risk and pose questions related to socio- political, economic and culturalconsiderations (Ansell and Vogel, 2006; van Asselt and Vos, 2008)

Molecular biology and pathogenicity of phytoplasmas

Phytoplasmas are a large group of plant-pathogenic wall-less, non-helical, bacteria associated with diseases, collectively referred to as yellows diseases, in more than a thousand plant species worldwide. Many of these diseases are of great economic importance. Phytoplasmas are difficult to study, in particular because all attempts at culturing these plant pathogens under axenic conditions have failed. With the introduction of molecular methods into phytoplasmology about two decades ago, the genetic diversity of phytoplasmas could be elucidated and a system for their taxonomic classification based on phylogenetic traits established. In addition, a wealth of information was generated on phytoplasma ecology and genomics, phytoplasma–plant host interactions and phytoplasma–insect vector relationships. Taxonomically, phytoplasmas are placed in the class Mollicutes, closely related to acholeplasmas, and are currently classified within the provisional genus ‘Candidatus Phytoplasma’ based primarily on 16S rDNA sequence analysis. Phytoplasmas are characterised by a small genome. The sizes vary considerably, ranging from 530 to 1350 kilobases (kb), with overlapping values between the various taxonomic groups and subgroups, resembling in this respect the culturable mollicutes. The smallest chromosome, about 530 kb, is known to occur in the Bermuda grass white leaf agent ‘Ca. Phytoplasma cynodontis’. This value represents the smallest mollicute chromosome reported to date. In diseased plants, phytoplasmas reside almost exclusively in the phloem sieve tube elements and are transmitted from plant to plant by phloem-feeding homopteran insects, mainly leafhoppers and planthoppers, and less frequently psyllids. Most of the phytoplasma host plants are angiosperms in which a wide range of specific and non-specific symptoms are induced. Phytoplasmas have a unique and complex life cycle that involves colonisation of different environments, the plant phloem and various organs of the insect vectors. Furthermore, many phytoplasmas have an extremely wide plant host range. The dynamic architecture of phytoplasma genomes, due to the occurrence of repetitive elements of various types, may account for variation in their genome size and adaptation of phytoplasmas to the diverse environments of their plant and insect hosts. The availability of five complete phytoplasma genome sequences has made it possible to identify a considerable number of genes that are likely to play major roles in phytoplasma–host interactions. Among these, there are genes encoding surface membrane proteins and effector proteins. Also, it has been shown that phytoplasmas dramatically alter their gene expression upon switching between plant and insect hosts

Landschaftsökologische Analyse und Diagnose von Heidemooren für die Landschaftsplanung im deutsch-niederländischen Grenzraum (Naturpark Schwalm-Nette) : mit 3 Abbildungen und 2 Tabellen

Petra Kartte & Ernst Brunott

Untersuchungen zum Resistenzverhalten verschiedener Malus-Forbes gegen die Apfeltriebsucht und zur Schadwirkung des Erregers

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

APPLE PROLIFERATION EPIDEMICS DETECTED IN SCAB-RESISTANT APPLE TREES

In the Friuli-Venezia Giulia, a region of Italy, where serious epidemics of apple proliferation (AP) are known to occur, varieties resistant to scab (Venturia inaequalis (Cke.) Wint.) are increasingly being used in new orchards. The most important cvs are Florina, Prima and Priscilla. These varieties were planted from 1985 to 1990 in numerous orchards which were cultivated according to organic farming regimes with no insecticides used. The results obtained in two orchards during a 7-year period of investigation indicated that the three varieties resistant to scab are highly susceptible to AP. Florina was most susceptible (high infection rate) to AP while Priscilla was most sensitive (severely affected). The identification of the disease was based on symptom expression, DAPI (4'-6-diamidino-2-phenylindole) fluorescence technique, electron microscopy observations and by polymerase chain reaction (PCR). Neither complete spontaneous recovery nor death of AP-infected plants was noticed. The pattern of natural diffusion of AP does not seem to be uniform: the affected trees may be in line or grouped in certain spots of the orchards. This may indicate the activity of a not very mobile vector. It can be concluded that planting of Florina, Prima and Priscilla should be discouraged in areas where AP is a problem, particularly when organic farming regimes are being applied

Freier oder selbstverwalteter Wettbewerb Ein Gespraech ueber Konflikte zwischen Wettbewerbspolitik und Mittelstandsschutz

Bibliothek Weltwirtschaft Kiel B200,506 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman