frbreSuboptimal growth conditions caused by drought, temperature, salt and pathogen-related stresses are leading to worldwide yield losses in cultivated crops. It is anticipated that these issues become even bigger in the future, as climatic changes will cause more temperature and drought stress, and, in the meantime, the demand for plants for food, feed and bioenergy is increasing. Obviously, this encouraged the search and development of appropriate breeding strategies and has made crop stress tolerance a major objective in plant biotechnology research.