Plants are continuously exposed to biotic and abiotic stresses, such as pathogens (fungi, bacteria, viroids, and virus), drought, extreme temperature, trace elements, or salinity. Drought stress can severely impair plant growth and production. However, as a function of stress intensity, various defense responses can take place in plants. The aim of this review is to present first responses of plants, meaning stress perception, signal production and amplification and expression of first genes involved in defenses. In order to counteract drought effect, plants developed two main defense strategies, meaning the abscisic acid dependent and independent pathways.