From the pre-historic era to modern times, cereal grains have been the most important source of human nutrition, and have helped sustain the increasing population and the development of human civilization. In order to meet the food needs of the 21st century, food production must be doubled by the year 2025, and nearly tripled by 2050. Such enormous increases in food productivity cannot be brought about by relying entirely on conventional breeding methods, especially on less land per capita, with poor quality and quantity of water, and under rapidly deteriorating environmental conditions.