The course includes an initial description of the plant cell structure in order to recall the basics (and to fill up any shortcomings of formation). The same concept also applies to the next topic about the relationship between plant cell and expansion/growth, which will be analyzed in relation to external signals that plant cells receive. In order to deepen the signaling pathway, the molecular mechanisms are discussed, especially the role of G protein-linked receptors and of enzymatic receptors and receptors with proteolytic activities. After introducing the general aspects of the communication process, we shall discuss the specific mechanisms of cell communication in plants (role of Ca ions, photoreceptors, etc.) and how these specific signaling mechanisms are integrated into the developmental process of plants. The next topic is the study of specific environmental signals, such as the light-dependent process and the perception of light (such as the photoperiodism). At the end of course, it will be discussed the environmental elements that are source of stress (excessive light, water scarcity, high and low temperatures, saline stress). Next, we will discuss the molecular mechanisms regulating biotic interactions of plants with parasites (defense mechanisms). The last part of the course will cover the effects of environmental contaminants on the development of plants; we will also discuss how these effects will interface with the response to other stress forms. We will then present data about the effects of environmental contaminants on the perception of stress. The laboratory section will serve to integrate the concepts presented in class.