Evolution of wheat architecture, physiology, and metabolism during domestication and further cultivation: Lessons for crop improvement

In recent decades, genetic advances in yield improvement in the major cereal crops, including wheat, has stagnated or proceeded at a slower rate than is required to meet future global food demand, particularly in the face of climate change. To reverse this situation, and in view of the future climate scenario, there is a need to increase the genetic diversity of wheat to increase its productivity, quality, stability, and adaptation to local agro-environments. The abundant genetic resources and literature are a basis for wheat improvement. However, many species, such as wild relatives, landraces, and old cultivars have not been studied beyond their agronomic characteristics, highlighting the lack of understanding of the physiological and metabolic processes (and their integration) associated with higher productivity and resilience in limiting environments. Retrospective studies using wheat ancestors and modern cultivars may identify novel traits that have not previously been considered, or have been underestimated, during domestication and breeding, but that may contribute to future food security. This review describes existing wheat genetic diversity and changes that occurred during domestication and breeding, and considers whether mining natural variation among wheat ancestors offers an opportunity to enhance wheat agronomic performance, spike architecture, canopy- and organ-level photosynthetic capacity, and responses to abiotic stress, as well as to develop new wheat hybrids.