Plants interact with a large number of microoganisms which have a major impact on their growth either by establishing mutually beneficial symbiotic relationships or by developing as pathogens at the expense of the plant with deleterious effects. These microorganisms differ greatly not only in their nature (viruses, phytoplasmas, bacteria, fungi, nematodes, ... ) but also in the way they contact, penetrate and invade their host. Histology and cytology have brought an essential contribution to our knowledge of these phenomena. They have told us for instance, how specialized structures of the...

Microorganisms, including those genetically modified (GMOs), are increasingly being released deliberately into the environment for different purposes. One major interest is the use of antagonistic organisms for biological control of pests and plant diseases. Both in the development of biocontrol agents and their later risk assessment and product approval, there is a need for methods that facilitate monitoring of such introduced microorganisms. This book particularly addresses the various approaches for monitoring introduced fungi and the current status of techniques which may be...

When I received an invitation to attend the International Symposium on Lethal Yellowing being organised by the Centro de Investigacion Cientifica de Yucatan (CICy), I was excited and a little nostalgic. During the 1970s, a series of similar symposia had been held under the auspices of the loosely-constituted "International Council on Lethal Yellowing" (ICL Y). These were the years when the MLO cause for L Y was first proposed, a vector was found, the disease was racing across mainland Florida, USA and it was suspected of having jumped to Cozumel. Analogous diseases were also reported to be...

Research on the mechanisms of plant defense responses to stress and pathogen attack has attracted much attention in recent years. This increasing interest stems from the fact that the tools of molecular biology now enable us to study the molecular basis of old biological concepts such as host-pathogen recognition (and particularly the gene- for-gene relationship), hypersensitive cell death and systemic acquired resistance. Our knowledge about avirulence and resistance genes, elicitors, signal transduction and genes involved in plant defense is rapidly expanding. Moreover we are just beginning...

For investigators engaged in the study of toxins generally, and host-specific toxins in particular, it is a rare treat to attend a meeting in which toxins involved in plant pathogenesis are emphasized. A gathering of this type provides opportunity to consider the discovery of new toxins, their chemical structures, genes encoding enzymes that control their biosyntheses, their sites of action and physiological effects on plants, and their roles (if any) in pathological processes. Having acknowledged the inspiration fostered by a 'toxin meeting', however, it is important to point out that the...

During the last decade, research on Pseudomonas syringae pathovars and related pathogens has progressed rapidly, opening up many new avenues. The application of molecular genetics has provided new insights into determinants of pathogenicity and virulence. Progress has also been made in elucidating the chemical structures and modes of action of phytotoxins from Pseudomonas syringae; by establishing novel strategies for disease control; in biotechnological applications; by studying the resistant reaction of the plant with a combined biochemical and genetic approach; and in the...

In 1992 a Concerted Action Programme (CAP) was initiated by Peter Sijmons with the purpose of intensifying collaborations between 16 European laboratories working on plant-parasitic nematodes. The four-year programme entitled Resistance mechanisms against plant-parasitic nematodes' focused on molecular aspects of the interaction between sedentary nematodes and plants on the model system Arabidopsis and on novel resistance strategies. Funding was provided mainly for exchange visits between collaborating laboratories and for the organization of annual meetings. During the last annual...