Chapter 1. ABA in pathogen resistance (pathological point of view). Chapter 2. Mitogen Activated Protein Kinase (MAPK) cascade. Chapter 3. Trascription factors in abiotic and biotic stress responses-. Chapter 4. Ca2+ mediated signals/ Ca2+ dependent protein kinases /calmodulin and calmodulin like proteins / calcineurin like proteins. Chapter 5. Manipulation of plant hormonal crosstalk by microorganisms. Chapter 6. Pathogen Resistance in Environmentally Sensitive Arabidopsis Mutants. Chapter 7. Involvement of Reactive Oxygen Species/Nitric oxide in signal crosstalk