A Reappraisal of Polyploidy Events in Grasses (Poaceae) in a Rapidly Changing World

Simple Summary Polyploidy events have long been recognized as the primary driving force behind the survival of the vast majority of plant lineages, playing critical roles in crop evolution, speciation, and domestication. The fascinating modern genomics era has revealed that the genomes of all flowering plants have been polyploidized multiple times. To help safeguard the future of the global food supply in the face of climate change, a thorough understanding of polyploid genomes is critical, especially for the improvement of members of the grass family, Poaceae, which includes the world's big three cereals-rice, wheat, and maize-as well as some potential underutilized ancient grasses (such as teff) that are less well known or studied. This is becoming easier with rapid advances in genomic technologies. However, there are critical knowledge gaps and research needs among the well-studied and less-studied Poaceae polyploids that must be addressed, particularly the characteristics of polyploids that might either complicate or facilitate crop improvement programs. This review discusses the potential role for the Poaceae family in providing insights into the significance and specific features of polyploid genomes, as well as the emerging challenges and prospects for furthering polyploidy understanding in crop improvement. Around 80% of megaflora species became extinct at the Cretaceous-Paleogene (K-Pg) boundary. Subsequent polyploidy events drove the survival of thousands of plant species and played a significant historical role in the development of the most successful modern cereal crops. However, current and rapid global temperature change poses an urgent threat to food crops worldwide, including the world's big three cereals: rice, wheat, and maize, which are members of the grass family, Poaceae. Some minor cereals from the same family (such as teff) have grown in popularity in recent years, but there are important knowledge gaps regarding the similarities and differences between major and minor crops, including how polyploidy affects their biological processes under natural and (a)biotic stress conditions and thus the potential to harness polyploidization attributes for improving crop climate resilience. This review focuses on the impact of polyploidy events on the Poaceae family, which includes the world's most important food sources, and discusses the past, present, and future of polyploidy research for major and minor crops. The increasing accessibility to genomes of grasses and their wild progenitors together with new tools and interdisciplinary research on polyploidy can support crop improvement for global food security in the face of climate change.