Drought is one of the major environmental factors that inhibits many metabolic processes and constrains plant growth and crop productivity. The ongoing global warming and current climate changes are enlarging the land areas where plants experience water deficit. Understanding the responses of plants to their external environment is of importance with respect to basic research, but it is also an attractive target for improving stress tolerance [1]. Thus, our understanding of the drought adaptation mechanisms is of importance to meet the goal of increased plant productivity under the projected critical global scenarios that are related to water availability.