Diversity and knowledge of plant pathogens

OVERVIEW OF THE FOUR LESSONS

1. Fungal diseases as a worldwide threat to crop and ecosystems
   The course “Fungal Diseases as a Worldwide Threat to Crops and Ecosystems” offers an immersion into the diversity of pathogenic and fungiform fungi affecting plants. It explores their infection strategies (biotrophic, necrotrophic, hemibiotrophic), their life cycles, their modes of dispersal, and their effects on crops and natural ecosystems. Historical and contemporary examples illustrate their role in major agricultural crises (coffee rust, Dutch elm disease, late blight, etc.). The course also addresses emerging threats linked to climate change, intensive agriculture, and resistance to treatments, while presenting the main fungal and fungiform pathogens.
   
   2. On plant pathogenic bacteria
   This course offers a comprehensive exploration of phytopathogenic bacteria, from their effects on plants to their identification and management. It begins with an overview of the main symptoms they cause (watery spots, necrosis, wilting, etc.), then addresses their taxonomic diversity, the different levels of classification (species, pathovars, races) and their host specificities. The analysis continues with a study of their parasitic cycles and control strategies (selection of resistant varieties, biological control, epidemiological surveillance). Finally, the course presents methods of identification by molecular phylogeny and typing, in line with international phytosanitary policies.
   
   3. Parasitic plants
   The “Parasitic Plants” course explores the diversity, biology, and agronomic impacts of parasitic plants, true “plant vampires” capable of diverting water and nutrients from their hosts. After an introduction to the different forms of parasitism, the course presents the main families concerned, their strategies (hemiparasites or holoparasites) and the importance of the haustorium, the vascular connection organ. Two major genera are studied: witchweeds (Striga) and broomrapes (Orobanche, Phelipanche), formidable crop parasites. Finally, the course addresses germination signals, spoliation mechanisms, and the challenges posed by current control methods.
   
   4. Study of the rose resistance against black spot disease
   This course explores the rose as a model for studying ornamental plants through resistance to black spot disease (Diplocarpon rosae). It presents the challenges associated with this disease, the limitations of chemical control, and qualitative and quantitative genetic approaches to resistance. The course covers evaluation methods, fungal strain diversity, QTL mapping, and alternative solutions such as bioprotection, illustrated by the ROBIO project.